Academic Appointments

Administrative Appointments

  • Steering Committee Member, Stanford Medicine Teaching and Mentoring Academy (2017 - Present)
  • Co-Director, Clinical Research Scholarly Concentration Program (2017 - Present)
  • Co-Director, Spectrum NIH TL1 Program (2013 - 2018)
  • Co-Director, MS program in Clinical Research & Epidemiology (2012 - Present)

Honors & Awards

  • Marjorie K. Ionta Award for Outstanding Graduate Student in Physical Therapy, MGH - Inst of Health Professions (1990)
  • Teaching Award, Division of Epidemiology (HRP) (2006, 2008, 2010, 2011, 2012)
  • Honorary Cap and Gown membership, Women’s honor society at Stanford (2009)
  • The Kaiser Foundation Award for Excellence in Preclinical Teaching, Stanford University School of Medicine (2010)

Professional Education

  • PhD, Stanford University, Epidemiology (2003)
  • MS, U Mass (Amherst), Biostatistics (1998)
  • MS, MGH Inst of Health Professions, Physical Therapy (1991)

Current Research and Scholarly Interests

My research interest focuses on the epidemiology of Parkinson’s disease and amyotrophic lateral sclerosis, specifically evaluating the genetic and environmental contributions to these neurodegenerative disorders. I am also interested in studying the relation of cognition, estradiol exposure (endogenous and exogenous), and genetic factors.

Our research group developed an expanded screening questionnaire for diagnosing restless legs syndrome and evaluated the reliability and validity of this instrument. We found that while the sensitivity of the recommended set of three questions for screening RLS is good (86%), the specificity is poor (45%) when examined in a sample that over-represents subjects with conditions that are commonly misclassified as RLS. We showed that specificity can be improved by including separate questions on cardinal features, as used in our expanded questionnaire, and by including a few questions that identify RLS mimics, thereby reducing false positives.

A copy of the expanded questionnaire can be accessed under "Links" (which can be viewed under the Bio tab). It is a research tool that is being made available “as is” and may be used freely for any purpose under the following terms and conditions:
- No modifications may be made to ensure the validity and reliability of the questionnaire.
-The following acknowledgement should be used in any publication or reproduction:
Popat RA, Van Den Eeden SK, Tanner CM , Kushida C, Rama A, Black J, Bernstein AL, Kasten M, Chade A,Leimpeter A, Cassidy J, McGuire V, Nelson LM. Reliability and validity of two self-administered questionnaires for screening restless legs syndrome in population-based studies. Sleep Medicine 2010; 11(2): 154-160.

2023-24 Courses

Stanford Advisees

Graduate and Fellowship Programs

All Publications

  • Racial and Ethnic Disparities in Intensity of Care at the End of Life for Patients With Lung Cancer: A 13-Year Population-Based Study. Journal of clinical oncology : official journal of the American Society of Clinical Oncology Rodriguez, G. M., Popat, R., Rosas, L. G., Patel, M. I. 2024: JCO2301045


    Lung cancer is the leading cause of cancer death in the United States. Disparities in lung cancer mortality among racial and ethnic minorities are well documented. Less is known as to whether racial and ethnic minority patients with lung cancer experience higher rates of intensity of care at the end of life (EOL) compared with non-Hispanic White (NHW) patients.We conducted a population-based analysis of patients 18 years and older with a lung cancer diagnosis who died between 2005 and 2018 using the California Cancer Registry linked to patient discharge data abstracts. Our primary outcome was intensity of care in the last 14 days before death (defined as any hospital admission or emergency department [ED] visit, intensive care unit [ICU] admission, intubation, cardiopulmonary resuscitation [CPR], hemodialysis, and death in an acute care setting). We used multivariable logistic regression models to evaluate associations between race and ethnicity and intensity of EOL care.Among 207,429 patients with lung cancer who died from 2005 to 2018, the median age was 74 years (range, 18-107) and 106,821 (51%) were male, 146,872 (70.8%) were NHW, 1,045 (0.5%) were American Indian, 21,697 (10.5%) were Asian Pacific Islander (API), 15,490 (7.5%) were Black, and 22,325 (10.8%) were Hispanic. Compared with NHW patients, in the last 14 days before death, API, Black, and Hispanic patients had greater odds of a hospital admission, an ICU admission, intubation, CPR, and hemodialysis and greater odds of a hospital or ED death.Compared with NHW patients, API, Black, and Hispanic patients who died with lung cancer experienced higher intensity of EOL care. Future studies should develop approaches to eliminate such racial and ethnic disparities in care delivery at the EOL.

    View details for DOI 10.1200/JCO.23.01045

    View details for PubMedID 38478794

  • Characterization and burden of localized back pain versus back pain with chronic overlapping pain conditions. Pain practice : the official journal of World Institute of Pain Terkawi, A. S., Popat, R. A., Mackey, S. 2023


    Chronic low back pain (cLBP) is the most common cause of years lived with disability (YLD). Chronic overlapping pain conditions (COPCs) is a relatively new taxonomy for widespread pain. Researchers have postulated that patients with COPCs have more pain-related impact than those with isolated pain conditions. We know little about the combination of COPCs with cLBP. This study aims to characterize patients with isolated cLBP compared to those with cLBP and associated COPCs across multiple domains of physical, psychological, and social functioning.Using Stanford's CHOIR registry-based learning health system, we performed a cross-sectional study on patients with localized cLBP (group L) versus cLBP with COPCs (group W). We used demographic, PROMIS (Patient-Reported Outcomes Measurement Information System), and legacy survey data to characterize the physical, psychological, social, and global health outcomes. We further subdivided the COPCs into intermediate and severe based on the number of body regions involved. We used descriptive statistics and generalized linear regression models to characterize and compare the pain groups.Among 8783 patients with cLBP, 485 (5.5%) had localized cLBP (Group L) without widespread pain. Compared to Group L, patients in Group W were more likely to be females, younger, and reported longer duration of pain. Although the mean pain scores were significantly higher in group W, this difference did not appear clinically significant (average pain scores MD -0.73, 95% CI [-0.91 to -0.55]). Group W had significantly worse outcomes in all PROMIS outcomes. However, outcomes with large clinical differences (Cohen's d > 0.5) were fatigue (MD = -7.0, 95% CI [-8.0 to -6.1]); sleep impairment (MD = -6.2, 95% CI [-7.1 to -5.3]); sleep disturbance (MD = -5.3, 95% CI [-6.2 to -4.5]); pain behavior (MD = -2.2, 95% CI [-2.5 to -1.8]); physical function (MD = 4.0, 95% CI [3.2-5.0]); pain interference (MD = -3.4, 95% CI [-4.0 to -2.8]); and anxiety (MD = -4.9, 95% CI [-5.7 to -4.0]). Adjusted analysis controlling for age, gender, BMI category, and duration of pain confirmed worsening of all outcomes with more widespread pain.COPCs are a common presentation with cLBP. The combination of COPCs with cLBP is associated with significantly worse physical, psychological, social, and global health outcomes. This information may identify patients with COPCs and cLBP to optimally risk and treatment stratify their care and individualize their management.

    View details for DOI 10.1111/papr.13267

    View details for PubMedID 37392043

  • Implementation and evaluation of an elective quality improvement curriculum for preclinical students: a prospective controlled study. BMC medical education Aredo, J. V., Ding, J. B., Lai, C. H., Trimble, R., Bromley-Dulfano, R. A., Popat, R. A., Shieh, L. 2023; 23 (1): 66


    BACKGROUND: Quality improvement (QI) is a systematic approach to improving healthcare delivery with applications across all fields of medicine. However, exposure to QI is minimal in early medical education. We evaluated the effectiveness of an elective QI curriculum in teaching preclinical health professional students foundational QI concepts.METHODS: This prospective controlled cohort study was conducted at a single academic institution. The elective QI curriculum consisted of web-based video didactics and exercises, supplemented with in-person classroom discussions. An optional hospital-based QI project was offered. Assessments included pre- and post-intervention surveys evaluating QI skills and beliefs and attitudes, quizzes, and Quality Improvement Knowledge Application Tool-Revised (QIKAT-R) cases. Within-group pre-post and between-group comparisons were performed using descriptive statistics.RESULTS: Overall, 57 preclinical medical or physician assistant students participated under the QI curriculum group (N=27) or control group (N=30). Twenty-three (85%) curriculum students completed a QI project. Mean quiz scores were significantly improved in the curriculum group from pre- to post-assessment (Quiz 1: 2.0, P<0.001; Quiz 2: 1.7, P=0.002), and the mean differences significantly differed from those in the control group (Quiz 1: P<0.001; Quiz 2: P=0.010). QIKAT-R scores also significantly differed among the curriculum group versus controls (P=0.012). In the curriculum group, students had improvements in their confidence with all 10 QI skills assessed, including 8 that were significantly improved from pre- to post-assessment, and 4 with significant between-group differences compared with controls. Students in both groups agreed that their medical education would be incomplete without a QI component and that they are likely to be involved in QI projects throughout their medical training and practice.CONCLUSIONS: The elective QI curriculum was effective in guiding preclinical students to develop their QI knowledge base and skillset. Preclinical students value QI as an integral component of their medical training. Future directions involve evaluating the impact of this curriculum on clinical clerkship performance and across other academic institutions.

    View details for DOI 10.1186/s12909-023-04047-0

    View details for PubMedID 36703204

  • The association of hearing problems with social network strength and depressive symptoms: the cardiovascular health study. Age and ageing Dobrota, S. D., Biggs, M. L., Pratt, S., Popat, R., Odden, M. C. 2022; 51 (8)


    BACKGROUND: research on the association between hearing impairment and psychosocial outcomes is not only limited but also yielded mixed results.METHODS: we investigated associations between annual self-reports of hearing problems, depressive symptoms and social network strength among 5,888 adults from the Cardiovascular Health Study over a period of 9 years. Social network strength and depressive symptoms were defined using the Lubben Social Network Scale (LSNS), and the Center for Epidemiological Studies Depression Scale (CES-D).RESULTS: hearing problems were associated with weaker social networks and more depressive symptoms. These association differed for prevalent versus incident hearing problems. Participants with prevalent hearing problems scored an adjusted 0.47 points lower (95% CI: -2.20, -0.71) on the LSNS and 0.71 points higher (95% CI: 0.23, 1.19) on the CES-D than those without hearing problems. Participants with incident hearing problems had a greater decline of 0.12 points (95% CI: -0.12, -0.03) per year in social network score than individuals with no hearing problems after adjusting for confounders. Females appeared to be more vulnerable to changes in social network strength than males (P-value for interaction=0.02), but not for changes in depressive score. Accounting for social network score did not appear to attenuate the association between hearing problems and depressive score.CONCLUSION: findings suggest that older adults with prevalent hearing problems may be more at risk for depression, but individuals with incident hearing problems may be at greater risk for a winnowing of their social network.

    View details for DOI 10.1093/ageing/afac181

    View details for PubMedID 35977151

  • Dysgeusia and Dysosmia in Chronic Kidney Disease: NHANES 2011-2014. Journal of renal nutrition : the official journal of the Council on Renal Nutrition of the National Kidney Foundation Vengalasetti, Y. V., Chertow, G. M., Popat, R. 2021


    OBJECTIVE: Dysgeusia and dysosmia are known to be associated with end-stage renal disease. Whether dysgeusia and dysosmia are associated with nondialysis-requiring chronic kidney disease (CKD) is unknown.METHODS: We utilized data from the National Health and Nutrition Examination Survey during years 2011-14. We classified CKD by stage using standard criteria for the estimated glomerular filtration rate and the urine albumin-to-creatinine ratio. We used multivariable logistic regression analysis to determine the independent associations among CKD, CKD stage, and dysgeusia and dysosmia using a ChemoSensory Questionnaire.RESULTS: After adjusting for the residual effects of age, sex, self-reported race, and diabetes, nondialysis-requiring CKD was significantly associated with dysgeusia ([odds ratio, 95% confidence interval] 1.34 [1.05, 1.70]); the association with dysosmia was of borderline significance, odds ratio 1.27 (0.97, 1.68). Odds of dysgeusia were higher at more severe CKD stages.CONCLUSION: Nondialysis-requiring CKD is significantly associated with self-reported dysgeusia.

    View details for DOI 10.1053/j.jrn.2021.11.003

    View details for PubMedID 35339348

  • Impact of Low-Dose CT Screening for Primary Lung Cancer on Subsequent Risk of Brain Metastasis. Journal of thoracic oncology : official publication of the International Association for the Study of Lung Cancer Su, C. C., Wu, J. T., Neal, J. W., Popat, R. A., Kurian, A. W., Backhus, L. M., Nagpal, S., Leung, A. N., Wakelee, H. A., Han, S. S. 2021


    Brain metastasis (BM) is one of the most common metastases from primary lung cancer (PLC). Recently, the National Lung Screening Trial (NLST) demonstrated the efficacy of low-dose computed tomography (LDCT) screening on LC mortality reduction. However, it remains unknown if early detection of PLC through LDCT may be potentially beneficial in reducing the risk of subsequent metastases. Our study aimed to investigate the impact of LDCT screening for PLC on the risk of developing BM after PLC diagnosis.We used NLST data to identify 1,502 participants who were diagnosed with PLC in 2002-2009 and have follow-up data for BM. Cause-specific competing risk regression was applied to evaluate an association between BM risk and the mode of PLC detection-i.e., LDCT screen-detected versus non-LDCT screen-detected. Subgroup analyses were conducted in early-stage PLC patients and those who underwent surgery for PLC.Of 1502 participants, 41.4% had PLC detected through LDCT-screening versus 58.6% detected through other methods, e.g., chest X-Ray or incidental detection. Patients whose PLC was detected with LDCT-screening had a significantly lower 3-year incidence of BM (6.5%) versus those without (11.9%), with a cause-specific hazard ratio (HR) of 0.53 (p=0.001), adjusting for PLC stage, histology, diagnosis age and smoking status. This significant reduction in BM risk among PLCs detected through LDCT-screening persisted in subgroups of early-stage PLC participants (HR 0.47, p=0.002) and those who underwent surgery (HR 0.37, p=0.001).Early detection of PLC using LDCT-screening is associated with lower risk of BM after PLC diagnosis based on a large population-based study.

    View details for DOI 10.1016/j.jtho.2021.05.010

    View details for PubMedID 34091050

  • Prevalence of a Diagnosis of Osteopenia/Osteoporosis Amongst Patients with Systemic Sclerosis and Identification of Associated Clinical Factors Wang, G., Mar, D., Wu, J., Simard, J., Popat, R., Chung, L. WILEY. 2020
  • Diagnostic Utility of Reduced Electroencephalography for Seizure Detection: A Systematic Review Gururangan, K., Razavi, B., Popat, R. LIPPINCOTT WILLIAMS & WILKINS. 2020
  • What Matters in Parkinson's Disease: Sex, Number of Children, or Birth Cohort? Movement disorders : official journal of the Movement Disorder Society Popat, R. A., Nelson, L. M. 2020; 35 (7): 1108–10

    View details for DOI 10.1002/mds.28059

    View details for PubMedID 32691910

  • EmPHasis-10 as a Measure of Health-Related Quality of Life in Pulmonary Arterial Hypertension: data from PHAR. The European respiratory journal Borgese, M. n., Badesch, D. n., Bull, T. n., Chakinala, M. n., DeMarco, T. n., Feldman, J. n., Ford, H. J., Grinnan, D. n., Klinger, J. R., Bolivar, L. n., Shlobin, O. A., Frantz, R. P., Sager, J. S., Mathai, S. C., Kawut, S. n., Leary, P. n., Gray, M. P., Popat, R. A., Zamanian, R. T. 2020


    While the performance of the emPHasis-10 (e10) score has been evaluated against limited patient characteristics within the United Kingdom, there is an unmet need for exploring the performance of the e10 score among PAH patients in the United States.Using the Pulmonary Hypertension Association Registry, we evaluated relationships between the e10 score and demographic, functional, hemodynamics, and additional clinical characteristics at baseline and over time. Furthermore, we derived a minimally important difference (MID) estimate for the e10 score.We analysed data from 565 PAH (75% female) adults 55.6±16.0 years of age. At baseline, the e10 score had notable correlation with factors expected to impact quality of life in the general population, including age, education level, income, smoking status, and body mass index. Clinically important parameters including six-minute walk distance and B-type natriuretic peptide/N-terminal-pro BNP were also significantly associated with e10 score at baseline and over time. We generated a MID estimate for the e10 score of -6.0 points (range -5.0 to -7.6 points).The e10 score was associated with demographic and clinical patient characteristics suggesting that HRQoL in PAH is influenced by both social factors and indicators of disease severity. Future studies are needed to demonstrate the impact of the e10 score on clinical decision-making and its potential utility for assessing clinically important interventions.

    View details for DOI 10.1183/13993003.00414-2020

    View details for PubMedID 33243844

  • Racial and Ethnic Disparities in Hospital-Based Care Associated with Postpartum Depression. Journal of racial and ethnic health disparities Chan, A. L., Guo, N. n., Popat, R. n., Robakis, T. n., Blumenfeld, Y. Y., Main, E. n., Scott, K. A., Butwick, A. J. 2020


    To estimate racial and ethnic differences in rates of hospital-based care associated with postpartum depression.This is a retrospective cohort study using International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM) diagnosis codes within data from the Office of Statewide Planning and Development in California. We included primiparous women who underwent delivery hospitalization from 2008 to 2012. The primary outcome was the first postpartum hospital encounter with a ICD-9-CM code for depression over a 9-month period after delivery. We examined the cumulative incidence of hospital-based care for postpartum depression by race/ethnicity. Logistic regression was used to estimate relative risk.The study cohort consisted of 984,167 primiparous women: 314,037 (32%) were non-Hispanic White; 59,754 (6%) were non-Hispanic Black; 150,855 (15%) were non-Hispanic Asian; 448,770 (46%) were Hispanic; and 10,399 (1%) were other races. The cumulative incidence of hospital-based care for postpartum depression was highest for Black women (39; 95% CI = 34-44 per 10,000 deliveries) and lowest for Asian women (7; 95% CI = 5-8 per 10,000 deliveries). Compared with White women, hospital-based care for postpartum depression was more likely to be provided to Black women (OR = 2.3; 95% CI = 1.9-2.7), whereas care was less likely for Asians (OR = 0.4; 95% CI = 0.3-0.5) and Hispanics (OR = 0.8; 95% CI = 0.7-1.0). Similar findings were observed after excluding women with antepartum depression, adjusting for sociodemographic and clinical variables, and stratifying according to care settings.Compared with White women, hospital-based care for postpartum depression more frequently impacts Black women. Identifying and improving inequities in access to and utilization of mental health care for postpartum women should be a maternal health priority.

    View details for DOI 10.1007/s40615-020-00774-y

    View details for PubMedID 32474833

  • Association of Sex With Postoperative Mortality Among Patients With Heart Failure Who Underwent Elective Noncardiac Operations. JAMA network open Mattingly, A. S., Lerman, B. J., Popat, R., Wren, S. M. 2019; 2 (11): e1914420


    Importance: Sex differences in postoperative outcomes in patients with heart failure (HF) have not been well characterized. Women generally experience a lower postoperative mortality risk after noncardiac operations. It is unclear if this pattern holds among patients with HF.Objectives: To determine if the risk of postoperative mortality is associated with sex among patients with HF who underwent noncardiac operations and to determine if sex is associated with the relationship between HF and postoperative mortality.Design, Setting, and Participants: This multisite cohort study used data from the US Department of Veterans Affairs Surgical Quality Improvement Project database for all patients who underwent elective noncardiac operations from October 1, 2009, to September 30, 2016, with a minimum of 1 year follow-up. The data analysis was conducted from May 1, 2018, to August 31, 2018.Exposures: Heart failure, left ventricular ejection fraction, and sex.Main Outcomes and Measures: Postoperative mortality at 90 days.Results: Among 609 735 patients who underwent elective noncardiac operations from 2009 to 2016, 47 997 patients had HF (7.9%; mean [SD] age, 68.6 [10.1] years; 1391 [2.9%] women) and 561 738 patients did not have HF (92.1%; mean [SD] age, 59.4 [13.4] years; 50 862 [9.1%] women). Among patients with HF, female sex was not independently associated with 90-day postoperative mortality (adjusted odds ratio [aOR], 0.97; 95% CI, 0.71-1.32). Although HF was associated with increased odds of postoperative mortality in both sexes compared with their peers without HF, the odds of postoperative mortality were higher among women with HF (aOR, 2.44; 95% CI, 1.73-3.45) than men with HF (aOR, 1.64; 95% CI, 1.54-1.74), suggesting that HF may negate the general protective association of female sex with postoperative mortality (P for interaction of HF*sex=.03). This pattern was consistent across all levels of left ventricular ejection fraction.Conclusions and Relevance: Although HF was associated with increased odds of postoperative mortality in both sexes compared with their peers without HF, the odds of postoperative mortality were higher among women with HF than men with HF, suggesting that HF may negate the general protective association of female sex with postoperative mortality risk in noncardiac operations.

    View details for DOI 10.1001/jamanetworkopen.2019.14420

    View details for PubMedID 31675085

  • Association Between Heart Failure and Postoperative Mortality Among Patients Undergoing Ambulatory Noncardiac Surgery. JAMA surgery Lerman, B. J., Popat, R. A., Assimes, T. L., Heidenreich, P. A., Wren, S. M. 2019


    Importance: Heart failure is an established risk factor for postoperative mortality, but how heart failure is associated with operative outcomes specifically in the ambulatory surgical setting is not well characterized.Objective: To assess the risk of postoperative mortality and complications in patients with vs without heart failure at various levels of echocardiographic (left ventricular systolic dysfunction) and clinical (symptoms) severity who were undergoing ambulatory surgery.Design, Setting, and Participants: In this US multisite retrospective cohort study of all adult patients undergoing ambulatory, elective, noncardiac surgery in the Veterans Affairs Surgical Quality Improvement Project database during fiscal years 2009 to 2016, a total of 355 121 patient records were identified and analyzed with 1 year of follow-up after surgery (final date of follow-up September 1, 2017).Exposures: Heart failure, left ventricular ejection fraction, and presence of signs or symptoms of heart failure within 30 days of surgery.Main Outcomes and Measures: The primary outcomes were postoperative mortality at 90 days and any postoperative complication at 30 days.Results: Among 355 121 total patients, outcome data from 19 353 patients with heart failure (5.5%; mean [SD] age, 67.9 [10.1] years; 18 841 [96.9%] male) and 334 768 patients without heart failure (94.5%; mean [SD] age, 57.2 [14.0] years; 301 198 [90.0%] male) were analyzed. Compared with patients without heart failure, patients with heart failure had a higher risk of 90-day postoperative mortality (crude mortality risk, 2.00% vs 0.39%; adjusted odds ratio [aOR], 1.95; 95% CI, 1.69-2.44), and risk of mortality progressively increased with decreasing systolic function. Compared with patients without heart failure, symptomatic patients with heart failure had a greater risk of mortality (crude mortality risk, 3.57%; aOR, 2.76; 95% CI, 2.07-3.70), as did asymptomatic patients with heart failure (crude mortality risk, 1.85%; aOR, 1.85; 95% CI, 1.60-2.15). Patients with heart failure had a higher risk of experiencing a 30-day postoperative complication than did patients without heart failure (crude risk, 5.65% vs 2.65%; aOR, 1.10; 95% CI, 1.02-1.19).Conclusions and Relevance: In this study, among patients undergoing elective, ambulatory surgery, heart failure with or without symptoms was significantly associated with 90-day mortality and 30-day postoperative complications. These data may be helpful in preoperative discussions with patients with heart failure undergoing ambulatory surgery.

    View details for DOI 10.1001/jamasurg.2019.2110

    View details for PubMedID 31290953

  • Association of Left Ventricular Ejection Fraction and Symptoms With Mortality After Elective Noncardiac Surgery Among Patients With Heart Failure JAMA Lerman, B. J., Popat, R. A., Assimes, T., Heidenreich, P., Wren, S. M. 2019; 321 (6): 572-579

    View details for DOI 10.1001/jama.2019.0156

  • Practice Patterns in Perioperative Nonopioid Analgesic Administration by Anesthesiologists in a Veterans Affairs Hospital. Pain medicine (Malden, Mass.) Kwong, J. Z., Mudumbai, S. C., Hernandez-Boussard, T. n., Popat, R. A., Mariano, E. R. 2019


    Although multimodal analgesia (MMA) is recommended for perioperative pain management, previous studies have found substantial variability in its utilization. To better understand the factors that influence anesthesiologists' choices, we assessed the associations between patient or surgical characteristics and number of nonopioid analgesic modes received intraoperatively across a variety of surgeries in a university-affiliated Veteran Affairs hospital.We included elective inpatient surgeries (orthopedic, thoracic, spine, abdominal, and pelvic procedures) that used at least one nonopioid analgesic within a one-year period. Multivariable multinomial logistic regression models were used to estimate adjusted odds ratios and 95% confidence intervals (CIs). We also described the combinations of analgesia used in each surgical subtype and conducted exploratory analyses to test the associations between the number of modes used and postoperative outcomes.Of the 1,087 procedures identified, 33%, 53%, and 14% were managed with one, two, and three or more modes, respectively. Older patients had lower odds of receiving three or more modes (adjusted odds ratio [aOR] = 0.28, 95% confidence interval [CI] = 0.15-0.52), as were patients with more comorbidities (two modes: aOR = 0.87, 95% CI = 0.79-0.96; three or more modes: aOR = 0.81, 95% CI = 0.71-0.94). Utilization varied across surgical subtypes P < 0.0001). Increasing the number of modes, particularly use of regional anesthesia, was associated with shorter length of stay.Our study suggests that age, comorbidities, and surgical type contribute to variability in MMA utilization. Risks and benefits of multiple modes should be carefully considered for older and sicker patients. Future directions include developing patient- and procedure-specific perioperative MMA recommendations.

    View details for DOI 10.1093/pm/pnz226

    View details for PubMedID 31559430

  • Quality of surgical randomized controlled trials in hand surgery: a systematic review. The Journal of hand surgery, European volume Long, C., desJardins-Park, H. E., Popat, R., Fox, P. M. 2018: 1753193418780184


    We assessed the quantity, quality and trends of randomized controlled trials comparing hand surgical interventions. Study characteristics were collected for 125 randomized controlled trials comparing hand surgical interventions. The Jadad scale (0-5), which assesses methodological quality of trials, was calculated. Logistic regressions were conducted to determine associations with the Jadad score. The studies were published between 1981 and 2015, with an increase over time, most often in Journal of Hand Surgery (European). Mean study size was 68 patients. Mean Jadad score was 2.1, without improvement over time. Thirty percent conducted a power analysis and 8% an intention-to-treat analysis. Studies conducted in the United Kingdom and with smaller sample sizes, power analysis and intention-to-treat analysis were associated with a higher Jadad score. The quantity of trials has increased over time while methodological quality has remained low, indicating a need to improve quality of trials in hand surgery literature.

    View details for PubMedID 29896997

  • Pulmonary function after lung tumor stereotactic ablative radiotherapy depends on regional ventilation within irradiated lung. Radiotherapy and oncology Binkley, M. S., King, M. T., Shrager, J. B., Bush, K., Chaudhuri, A. A., Popat, R., Gensheimer, M. F., Maxim, P. G., Henry Guo, H., Diehn, M., Nair, V. S., Loo, B. W. 2017; 123 (2): 270-275


    To determine if regional ventilation within irradiated lung volume predicts change in pulmonary function test (PFT) measurements after stereotactic ablative radiotherapy (SABR) of lung tumors.We retrospectively identified 27 patients treated from 2007 to 2014 at our institution who received: (1) SABR without prior thoracic radiation; (2) pre-treatment 4-dimensional computed tomography (4-D CT) imaging; (3) pre- and post-SABR PFTs <15months from treatment. We defined the ventilation ratio (VR20BED3) as the quotient of mean ventilation (mean Jacobian-based per-voxel volume change on deformably registered inhale/exhale 4-D CT phases) within the 20Gy biologically effective dose (α/β=3Gy) isodose volume and that of the total lung volume (TLV).Most patients had moderate to very severe COPD by GOLD criteria (n=19, 70.1%). Higher VR20BED3 significantly predicted worse change in Forced Expiratory Volume/s normalized by baseline value (ΔFEV1/FEV1pre, p=0.04); n=7 had VR20BED3>1 (high regional ventilation) and worse ΔFEV1/FEV1pre (median=-0.16, range=-0.230 to -0.20). Five had VR20BED3<1 (low regional ventilation) and improved ΔFEV1/FEV1pre (median=0.13, range=0.07 to 0.20). In a multivariable linear model, increasing VR20BED3 and time to post-SABR PFT predicted decreasing ΔFEV1/FEV1pre (R(2)=0.25, p=0.03).After SABR to high versus low functioning lung regions, we found worsened or improved global pulmonary function, respectively. If pre-SABR VR20BED3 is validated as a predictor of eventual post-SABR PFT in larger studies, it may be used for individualized treatment planning to preserve or even improve pulmonary function after SABR.

    View details for DOI 10.1016/j.radonc.2017.03.021

    View details for PubMedID 28460826

  • Diagnostic Utility of Intraoperative Neurophysiological Monitoring for Intramedullary Spinal Cord Tumors: Systematic Review and Meta-Analysis. Clinical spine surgery Azad, T. D., Pendharkar, A. V., Nguyen, V. n., Pan, J. n., Connolly, I. D., Veeravagu, A. n., Popat, R. n., Ratliff, J. K., Grant, G. A. 2017


    Systematic review and meta-analysis.The aim of this study was to systematically evaluate the diagnostic utility of intraoperative neurophysiological monitoring (IONM) for detecting postoperative injury in resection of intramedullary spinal cord tumors (IMSCT).Surgical management of IMSCT can involve key neurological and vascular structures. IONM aims to assess the functional integrity of susceptible elements in real time. The diagnostic value of IONM for ISMCT has not been systematically evaluated.We performed a systematic review of the PubMed and MEDLINE databases for studies investigating the use of IONM for IMSCT and conducted a meta-analysis of diagnostic capability.Our search produced 257 citations. After application of exclusion criteria, 21 studies remained, 10 American Academy of Neurology grade III and 11 American Academy of Neurology grade IV. We found that a strong pooled mean sensitivity of 90% [95% confidence interval (CI), 84-94] and a weaker pooled mean specificity of 82% (95% CI, 70-90) for motor-evoked potential (MEP) recording changes. Somatosensory-evoked potential (SSEP) recording changes yielded pooled sensitivity of 85% (95% CI, 75-91) and pooled specificity of 72% (95% CI, 57-83). The pooled diagnostic odds ratio for MEP was 55.7 (95% CI, 26.3-119.1) and 14.3 (95% CI, 5.47-37.3) for SSEP. Bivariate analysis yielded summary receiver operative characteristic curves with area under the curve of 91.8% for MEPs and 86.3% for SSEPs.MEPs and SSEPs appear to be more sensitive than specific for detection of postoperative injury. Patients with perioperative neurological deficits are 56 times more likely to have had changes in MEPs during the procedure. We observed considerable variability in alarm criteria and interventions in response to IONM changes, indicating the need for prospective studies capable of defining standardized alarm criteria and responses.

    View details for PubMedID 28650882

  • First Trimester Hemoglobin A1c Prediction of Gestational Diabetes. American journal of perinatology Osmundson, S. S., Zhao, B. S., Kunz, L., Wang, E., Popat, R., Nimbal, V. C., Palaniappan, L. P. 2016; 33 (10): 977-982


    Objective The objective of this study is to examine whether a first trimester hemoglobin A1c (A1C) of 5.7 to 6.4% predicts an abnormal second trimester oral glucose tolerance test (OGTT). Methods We conducted a retrospective cohort study of all women screened with A1C through 13 (6/7) weeks' gestation between January 1, 2011, and December 31, 2012. Prediabetic women (A1C of 5.7-6.4%) were compared with women with a normal first trimester A1C (< 5.7%). The primary outcome was an abnormal 2-hour, 75-g OGTT as defined by the International Association of Diabetes and Pregnancy Study Groups. Results There were 2,812 women who met inclusion criteria of whom 6.7% (n = 189) were prediabetic. Women with prediabetes were more likely to have gestational diabetes mellitus (GDM) even after adjusting for potential confounders (29.1 vs. 13.7%; adjusted relative risk, 1.48; 95% confidence interval, 1.15-1.89). There were no statistically significant differences in secondary outcomes except that women with prediabetes had less excessive gestational weight gain. A prediabetic-range A1C in the first trimester was associated with a 13% sensitivity and a 94% specificity for predicting GDM Conclusion Although women with prediabetes by first trimester A1C are significantly more likely to have GDM, the low sensitivity of an A1C in this range renders it a poor test to identify women who will develop GDM.

    View details for DOI 10.1055/s-0036-1581055

    View details for PubMedID 27120479

  • An Innovative Blended Preclinical Curriculum in Clinical Epidemiology and Biostatistics: Impact on Student Satisfaction and Performance ACADEMIC MEDICINE Evans, K. H., Thompson, A. C., O'Brien, C., Bryant, M., Basaviah, P., Prober, C., Popat, R. A. 2016; 91 (5): 696-700


    There is little understanding of the impact of teaching clinical epidemiology and biostatistics in a flipped or blended format. At Stanford University School of Medicine, the quantitative medicine (QM) curriculum for first-year students was redesigned to use a blended format, in response to student feedback.The blended QM curriculum introduced in 2013 integrated self-paced, online learning with small-group collaborative learning. The authors analyzed the blended format's impact on student satisfaction and performance, comparing the pilot cohort of students (n = 101) with students who took the traditional curriculum in 2011 and 2012 (n = 178). They also analyzed QM resource utilization in 2013.The blended curriculum had a positive impact on satisfaction and mastery of core material. Comparing the 2013 blended cohort with the 2011-2012 traditional cohort, there were significant improvements in student satisfaction ratings (overall, P < .0001; organization, P < .0001; logical sequence, P = .008; value of content, P < .0001). The mean (SD) overall satisfaction rating for small-group sessions increased: 3.40 (1.03) in 2013 versus 2.79 (1.00) in 2011 and 2.83 (1.06) in 2012. Performance on the QM final exam showed no significant changes in 2013 versus 2011 and 2012. The majority of students in 2013 reported using the QM online videos as their primary learning resource (69%-85% across modules).The positive impact of the curricular elements studied will inform continued development of the QM curriculum. Features of the curriculum could serve as a model for future blended courses.

    View details for DOI 10.1097/ACM.0000000000001085

    View details for Web of Science ID 000375153500029

    View details for PubMedID 26796089

  • Time course and predictive factors for lung volume reduction following stereotactic ablative radiotherapy (SABR) of lung tumors RADIATION ONCOLOGY Binkley, M. S., Shrager, J. B., Chaudhuri, A., Popat, R., Maxim, P. G., Shultz, D. B., Diehn, M., Loo, B. W. 2016; 11


    Stereotactic ablative volume reduction (SAVR) is a potential alternative to lung-volume reduction surgery in patients with severe emphysema and excessive surgical risk. Having previously observed a dose-volume response for localized lobar volume reduction after stereotactic ablative radiotherapy (SABR) for lung tumors, we investigated the time course and factors associated with volume reduction.We retrospectively identified 70 eligible patients receiving lung tumor SABR during 2007-2013. We correlated lobar volume reduction (relative to total, bilateral lung volume [TLV]) with volume receiving high biologically effective doses (VXXBED3) and other pre-treatment factors in all patients, and measured the time course of volume changes on 3-month interval CT scans in patients with large V60BED3 (n = 21, V60BED3 ≥4.1 % TLV).Median CT follow-up was 15 months. Median volume reduction of treated lobes was 4.5 % of TLV (range 0.01-13.0 %), or ~9 % of ipsilateral lung volume (ILV); median expansion of non-target adjacent lobes was 2.2 % TLV (-4.6-9.9 %; ~4 % ILV). Treated lobe volume reduction was significantly greater with larger VXXBED3 (XX = 20-100 Gy, R (2)  = 0.52-0.55, p < 0.0001) and smaller with lower pre-treatment FEV1% (R (2)  = 0.11, p = 0.005) in a multivariable linear model. Maximum volume reduction was reached by ~12 months and persisted.We identified a multivariable model for lobar volume reduction after SABR incorporating dose-volume and pre-treatment FEV1% and characterized its time course.

    View details for DOI 10.1186/s13014-016-0616-8

    View details for Web of Science ID 000372776500001

    View details for PubMedCentralID PMC4791793

  • Factors Associated with Patient Press Ganey Satisfaction Scores for Ophthalmology Patients OPHTHALMOLOGY Long, C., Tsay, E. L., Jacobo, S. A., Popat, R., Singh, K., Chang, R. T. 2016; 123 (2): 242-247


    To determine which metrics from the Press Ganey patient satisfaction survey best correlate with "likelihood to recommend" among patients in an academic tertiary medical center practice setting.Cross-sectional study.Over a 3-month period, patients presenting to an academic practice who agreed to participate were enrolled in the study if they met the following entry criteria: (1) age ≥18 years, (2) ability to read and speak English, and (3) followed in this practice between 4 months and 4 years. A total of 196 patients were recruited.A 26-item abridged version of the Press Ganey survey typically distributed to patients via mail or e-mail after visiting the Stanford University Hospital was administered privately to each eligible patient of 2 different attending clinics at the conclusion of his or her visit. The 26 survey items were not modified for the purposes of the study and were administered such that participants could not be individually identified. The arithmetic mean score for the item "Likelihood of your recommending our practice to others" was calculated by assigning a value (0-100) to the Likert value associated with survey responses and correlated with the 25 other items using the differences in the mean scores.Response to survey items graded on a 1 to 5 standard Likert scale.The weighted mean patient survey score for the "likelihood to recommend" item for the junior faculty member was 95.9% and for the senior faculty member was 94.5%, respectively. For the remaining 25 items, "Amount of time the care provider spent with you" (Diff[1-2]=1.03; P < 0.0001) and "Ease of scheduling your appointment" (Diff[1-2]=0.99; P < 0.0001) best correlated with likelihood to recommend. In contrast, "Friendliness/courtesy of the care provider" (Diff[1-2]=0.29; P = 0.0045) correlated least with likelihood to recommend. Stratification based on provider did not affect the study results.The perception of time spent with the practitioner and ease of appointment scheduling are the 2 variables that best correlate with patients recommending their ophthalmologists to other prospective patients.

    View details for DOI 10.1016/j.ophtha.2015.09.044

    View details for Web of Science ID 000368362200014

  • Craniotomy for Resection of Meningioma: An Age-Stratified Analysis of the MarketScan Longitudinal Database WORLD NEUROSURGERY Connolly, I. D., Cole, T., Veeravagu, A., Popat, R., Ratliff, J., Li, G. 2015; 84 (6): 1864-1870


    We sought to describe complications after resection for meningioma with the use of longitudinal administrative data, which our group has shown recently to be superior to nonlongitudinal administrative data.We identified patients who underwent resection for meningioma between 2010 and 2012 in the Thomson Reuters MarketScan database. Current Procedural Terminology coding at inpatient visit was used to select for meningioma resection procedure. Comorbidities and complications were obtained by use of the International Classification of Diseases, Ninth Revision or Current Procedural Terminology coding. Associations between complications and demographic and clinical factors were evaluated with logistic regression.We identified a total of 2216 patients. Approximately 41% developed 1 or more perioperative complications. Approximately 15% were readmitted within 30 days of their procedure. The most frequent complications that occurred in our cohort were new postoperative seizures (11.8%), postoperative dysrhythmia (7.9%), intracranial hemorrhage (5.9%), and cerebral artery occlusion (5.4%). General neurosurgical complications and general neurologic complications occurred in 4.4% and 16.1% of patients, respectively. Nearly 55% of elderly patients (≥ 70 years) developed 1 or more perioperative complication (vs. 39% of nonelderly patients). After we adjusted for comorbidities, elderly status and male sex were found to be significantly associated with increased odds for a variety of complications.In this study, we report complication rates in patients undergoing resection for meningioma. Because of the longitudinal nature of the MarketScan database, we were able to capture a wide array of specific postoperative complications associated with meningioma resection procedures. Care should be taken in the selection of candidates for meningioma resection.

    View details for DOI 10.1016/j.wneu.2015.08.018

    View details for PubMedID 26318633

  • Reliability and Validity of the Pediatric Palliative Care Questionnaire for Measuring Self-Efficacy, Knowledge, and Adequacy of Prior Medical Education among Pediatric Fellows JOURNAL OF PALLIATIVE MEDICINE Brock, K. E., Cohen, H. J., Popat, R. A., Halamek, L. P. 2015; 18 (10): 842-848


    Interventions to improve pediatric trainee education in palliative care have been limited by a lack of reliable and valid tools for measuring effectiveness.We developed a questionnaire to measure pediatric fellows' self-efficacy (comfort), knowledge, and perceived adequacy of prior medical education. We measured the questionnaire's reliability and validity.The questionnaire contains questions regarding self-efficacy (23), knowledge (10), fellow's perceived adequacy of prior medical education (6), and demographics. The survey was developed with palliative care experts, and sent to fellows in U.S. pediatric cardiology, critical care, hematology/ oncology, and neonatal-perinatal medicine programs. Measures of reliability, internal consistency, and validity were calculated.One hundred forty-seven fellows completed the survey at test and retest. The self-efficacy and medical education questionnaires showed high internal consistency of 0.95 and 0.84. The test-retest reliability for the Self-Efficacy Summary Score, measured by intraclass correlation coefficient (ICC) and weighted kappa, was 0.78 (item range 0.44-0.81) and 0.61 (item range 0.36-0.70), respectively. For the Adequacy of Medical Education Summary Score, ICC was 0.85 (item range 0.6-0.78) and weighted kappa was 0.63 (item range 0.47-0.62). Validity coefficients for these two questionnaires were 0.88 and 0.92. Fellows answered a mean of 8.8/10 knowledge questions correctly; percentage agreement ranged from 65% to 99%.This questionnaire is capable of assessing self-efficacy and fellow-perceived adequacy of their prior palliative care training. We recommend use of this tool for fellowship programs seeking to evaluate fellow education in palliative care, or for research studies assessing the effectiveness of a palliative care educational intervention.

    View details for DOI 10.1089/jpm.2015.0110

    View details for PubMedID 26185912

  • Racial/Ethnic Differences in Gestational Diabetes Prevalence and Contribution of Common Risk Factors PAEDIATRIC AND PERINATAL EPIDEMIOLOGY Pu, J., Zhao, B., Wang, E. J., Nimbal, V., Osmundson, S., Kunz, L., Popat, R. A., Chung, S., Palaniappan, L. P. 2015; 29 (5): 436-443


    The White House, the American Heart Association, the Agency for Healthcare Research and Quality, and the National Heart, Lung and Blood Institute have all recently acknowledged the need to disaggregate Asian American subgroups to better understand this heterogeneous racial group. This study aims to assess racial/ethnic differences in relative contribution of risk factors of gestational diabetes mellitus (GDM) among Asian subgroups (Asian Indian, Chinese, Filipino, Japanese, Korean, and Vietnamese), Hispanics, non-Hispanic blacks, and non-Hispanic whites.Pregnant women in 2007-2012 were identified through California state birth certificate records and linked to the electronic health records in a large mixed-payer ambulatory care organisation in Northern California (n = 24 195). Relative risk and population attributable fraction (PAF) for specific racial/ethnic groups were calculated to assess the contributions of advanced maternal age, overweight/obesity (Centers for Disease Control and Prevention (CDC) standards and World Health Organization (WHO)/American Diabetes Association (ADA) body mass index cut-offs for Asians), family history of type 2 diabetes, and foreign-born status.GDM was most prevalent among Asian Indians (19.3%). Relative risks were similar across all race/ethnic groups. Advanced maternal age had higher PAFs in non-Hispanic whites (22.5%) and Hispanics (22.7%). Meanwhile family history (Asian Indians 22.6%, Chinese 22.9%) and foreign-borne status (Chinese 40.2%, Filipinos 30.2%) had higher PAFs in Asian subgroups. Overweight/obesity was the most important GDM risk factor for non-Hispanic whites, Hispanics, Asian Indians, and Filipinos when the WHO/ADA cut-off points were applied. Advanced maternal age was the only risk factor studied that was modified by race/ethnicity, with non-Hispanic white and Hispanic women being more adversely affected than other racial/ethnic groups.Overweight/obesity, advanced maternal age, family history of type 2 diabetes, and foreign-borne status are important risk factors for GDM. The relative contributions of these risk factors differ by race/ethnicity, mainly due to differences in population prevalence of these risk factors.

    View details for DOI 10.1111/ppe.12209

    View details for Web of Science ID 000359633400009

    View details for PubMedID 26201385

  • Factors associated with delays to surgical presentation in North-West Cameroon SURGERY Long, C., Tagang, E. T., Popat, R. A., Lawong, E. K., Brown, J. A., Wren, S. M. 2015; 158 (3): 756-763


    Few studies have examined critically the delays in definitive management for surgical diseases in Sub-Saharan Africa. This study investigates factors contributing to delays at Mbingo Baptist Hospital, a tertiary referral hospital in Cameroon.During a 6-week period, we randomly interviewed 220 patients (39.2%) admitted to the surgical or orthopedic service and/or their caregivers. All patients >age 15 years admitted with a diagnosis of cancer or urgent operative condition (defined as requiring a definitive operation within 48 hours of admission) including trauma were interviewed. Delay was defined as receiving treatment >7 days after symptoms appeared in the urgent cohort and >1 month for the cancer cohort.In the urgent cohort, 60.3% patients had delays >7 days to hospital presentation. Compared with nondelayed patients, delayed patients were more likely to have sought care >1 day after symptoms appeared (45.4% vs 6.3%, P < .0001) and to have received previous medical care (92.8% vs 73.4%, P = .0007). Of all patients who received previous care, those with delays, compared those with no delays, visited ≥2 other providers (50.5% vs 18.8%, P < .0001), received a surgical procedure at previous episode(s) of care (21.1% vs 6.4%, P = .026), and felt no improvement after this care (80.4% vs 61.0%, P = .003). In the cancer cohort, 100% experienced >1 month delay. 100% had received medical care prior to arriving at Mbingo Baptist Hospital, 81.4% sought care from at least 3 different facilities, and none believed this care addressed their health concerns.Significant delays most often were caused by time spent on previous failed attempts at care. This information can be used to inform policy discussions about optimal health care organization within the country.

    View details for DOI 10.1016/j.surg.2015.04.016

    View details for PubMedID 26067462

  • Live Video Diet and Exercise Intervention in Overweight and Obese Youth: Adherence and Cardiovascular Health. journal of pediatrics Nourse, S. E., Olson, I., Popat, R. A., Stauffer, K. J., Vu, C. N., Berry, S., Kazmucha, J., Ogareva, O., Couch, S. C., Urbina, E. M., Tierney, E. S. 2015; 167 (3): 533-9 e1


    To evaluate adherence of overweight and obese adolescents to a live video lifestyle intervention. The impact on vascular and functional health was also assessed.Twenty adolescents 14.5 ± 2.1 years of age with body mass index z-score 1.94 ± 0.43 were enrolled. The 12-week intervention included 3-times-weekly videoconference sessions with a trainer and weekly diet consultations. Adherence was evaluated by completion rate and percentage of sessions attended. Vascular health indices and traditional cardiovascular risk factors were obtained at baseline and study end.Seventeen participants (85%) completed the intervention. The participants attended 93 ± 11% of scheduled sessions. Reasons for absences included illness/injury (23%), school activities (21%), holidays (18%), forgetting the appointment (8%), Internet connectivity issues (7%), and family emergency (7%). Significant changes were observed in waist-hip ratio (0.87 ± 0.08 vs 0.84 ± 0.08, P = .03), total (159 ± 27 vs 147 ± 23 mg/dL, P = .004) and low-density lipoprotein cholesterol levels (91 ± 20 vs 81 ± 18 mg/dL, P = .004), volume of inspired oxygen per heartbeat at peak exercise (69 ± 16 vs 72 ± 15%, P = .01), and functional movement score (13 ± 2 vs 17 ± 1, P < .001). Participants with abnormal vascular function at baseline showed improvement in endothelial function and arterial stiffness indices (P = .01 and P = .04, respectively).A 12-week live video intervention promotes adherence among overweight and obese adolescents and shows promise for improving vascular and functional health. Integrating telehealth into preventive care has the potential to improve cardiovascular health in the youth at risk.

    View details for DOI 10.1016/j.jpeds.2015.06.015

    View details for PubMedID 26154402

  • Early surgical intervention or watchful waiting for the management of asymptomatic mitral regurgitation: a systematic review and meta-analysis. Annals of cardiothoracic surgery Goldstone, A. B., Patrick, W. L., Cohen, J. E., Aribeana, C. N., Popat, R., Woo, Y. J. 2015; 4 (3): 220-229


    Discordance between studies drives continued debate regarding the best management of asymptomatic severe mitral regurgitation (MR). The aim of the present study was to conduct a systematic review and meta-analysis of management plans for asymptomatic severe MR, and compare the effectiveness of a strategy of early surgery to watchful waiting.A systematic review was performed using the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) guidelines. Studies were excluded if they: (I) lacked a watchful waiting cohort; (II) included symptomatic patients; or (III) included etiologies other than degenerative mitral valve disease. The primary outcome of the study was all-cause mortality at 10 years. Secondary outcomes included operative mortality, repair rate, repeat mitral valve surgery, and development of new atrial fibrillation.Five observational studies were eligible for review and three were included in the pooled analysis. In asymptomatic patients without class I triggers (symptoms or ventricular dysfunction), pooled analysis revealed a significant reduction in long-term mortality with an early surgery approach [hazard ratio (HR) =0.38; 95% confidence interval (CI): 0.21-0.71]. This survival benefit persisted in a sub-group analysis limited to patients without class II triggers (atrial fibrillation or pulmonary hypertension) [relative risk (RR) =0.85; 95% CI: 0.75-0.98]. Aggregate rates of operative mortality did not differ between treatment arms (0.7% vs. 0.7% for early surgery vs. watchful waiting). However, significantly higher repair rates were achieved in the early surgery cohorts (RR =1.10; 95% CI: 1.02-1.18).Despite disagreement between individual studies, the present meta-analysis demonstrates that a strategy of early surgery may improve survival and increase the likelihood of mitral valve repair compared with watchful waiting. Early surgery may also benefit patients when instituted prior to the development of class II triggers.

    View details for DOI 10.3978/j.issn.2225-319X.2015.04.01

    View details for PubMedID 26309823

  • Risk of Cardiovascular Disease Associated with a Restless Legs Syndrome Diagnosis in a Retrospective Cohort Study from Kaiser Permanente Northern California. Sleep Van Den Eeden, S. K., Albers, K. B., Davidson, J. E., Kushida, C. A., Leimpeter, A. D., Nelson, L. M., Popat, R., Tanner, C. M., Bibeau, K., Quesenberry, C. P. 2015; 38 (7): 1009-1015


    Recent cross-sectional studies suggest that restless legs syndrome (RLS) may be associated with an increased prevalence of cardiovascular disease (CVD) comorbidity or risk factors. We evaluated whether primary or secondary RLS was associated with an increased risk of incident cardiovascular disease in a retrospective cohort study within Kaiser Permanente Northern California (KPNC).We identified members of KPNC with primary RLS and secondary RLS between 1999 and 2008 by an algorithm that incorporated longitudinal clinical records related to the diagnosis and treatment of RLS and comorbidities. We then matched each RLS case with up to 50 individuals with no clinical records of RLS by age, sex, race/ethnicity, zip code, and membership duration. For the analyses we excluded any individual with coronary artery disease (CAD: angina, acute myocardial infarction, coronary revascularization procedure, CAD death), CVD (CAD plus stroke), and hypertension at baseline. New cardiovascular events were determined from clinical records. Follow-up ended at an outcome event, disenrollment from KPNC, or death, whichever occurred earliest. There were over 473,358 person-y of follow-up in this cohort analysis with a mean follow-up time of 3.91 y and range from 6 mo to 12 y. Survival analysis techniques, including survival curves and proportional hazard regression models, were used to assess the association between RLS status and CVD.There were 7,621 primary RLS and 4,507 secondary RLS cases identified and included in the study. In general, primary RLS cases were younger and had less comorbidity than secondary RLS cases. During the follow-up period, CVD was diagnosed in 478 primary RLS cohort members, CAD was diagnosed in 310, and hypertension events were identified in 1,466. Diagnosis in secondary RLS cohort members was made during the follow-up period with 451, 338, and 598 CVD, CAD, and hypertension events, respectively. Subjects with primary RLS had a similar risk of incident CVD (hazard ratio (HR) = 0.95; 95% confidence interval (CI) = 0.86-1.04) and CAD (HR = 0.99; 95% CI = 0.89-1.13) to the comparison cohort, with a slight elevation in the risk of hypertension events (HR = 1.19; 95% CI = 1.12-1.25), after multivariable adjustment. Individuals classified as secondary RLS had a significant increased risk of CVD (HR = 1.33; 95% CI = 1.21-1.46), CAD (HR = 1.40; 95% CI = 1.25-1.56), and hypertension (HR = 1.28; 95% CI = 1.18-1.40).Primary restless legs syndrome (RLS) was not associated with new-onset cardiovascular disease (CVD) or coronary artery disease (CAD) but was associated with a slight increased risk of hypertension. In contrast, secondary RLS was associated with an increased risk of CVD, CAD, and hypertension.

    View details for DOI 10.5665/sleep.4800

    View details for PubMedID 26083613

    View details for PubMedCentralID PMC4481004

  • Lung Volume Reduction After Stereotactic Ablative Radiation Therapy of Lung Tumors: Potential Application to Emphysema INTERNATIONAL JOURNAL OF RADIATION ONCOLOGY BIOLOGY PHYSICS Binkley, M. S., Shrager, J. B., Leung, A. N., Popat, R., Trakul, N., Atwood, T. F., Chaudhuri, A., Maxim, P. G., Diehn, M., Loo, B. W. 2014; 90 (1): 216-223


    Lung volume reduction surgery (LVRS) improves dyspnea and other outcomes in selected patients with severe emphysema, but many have excessive surgical risk for LVRS. We analyzed the dose-volume relationship for lobar volume reduction after stereotactic ablative radiation therapy (SABR) of lung tumors, hypothesizing that SABR could achieve therapeutic volume reduction if applied in emphysema.We retrospectively identified patients treated from 2007 to 2011 who had SABR for 1 lung tumor, pre-SABR pulmonary function testing, and ≥6 months computed tomographic (CT) imaging follow-up. We contoured the treated lobe and untreated adjacent lobe(s) on CT before and after SABR and calculated their volume changes relative to the contoured total (bilateral) lung volume (TLV). We correlated lobar volume reduction with the volume receiving high biologically effective doses (BED, α/β = 3).27 patients met the inclusion criteria, with a median CT follow-up time of 14 months. There was no grade ≥3 toxicity. The median volume reduction of the treated lobe was 4.4% of TLV (range, -0.4%-10.8%); the median expansion of the untreated adjacent lobe was 2.6% of TLV (range, -3.9%-11.6%). The volume reduction of the treated lobe was positively correlated with the volume receiving BED ≥60 Gy (r(2)=0.45, P=.0001). This persisted in subgroups determined by high versus low pre-SABR forced expiratory volume in 1 second, treated lobe CT emphysema score, number of fractions, follow-up CT time, central versus peripheral location, and upper versus lower lobe location, with no significant differences in effect size between subgroups. Volume expansion of the untreated adjacent lobe(s) was positively correlated with volume reduction of the treated lobe (r(2)=0.47, P<.0001).We identified a dose-volume response for treated lobe volume reduction and adjacent lobe compensatory expansion after lung tumor SABR, consistent across multiple clinical parameters. These data serve to inform our ongoing prospective trial of stereotactic ablative volume reduction (SAVR) for severe emphysema in poor candidates for LVRS.

    View details for DOI 10.1016/j.ijrobp.2014.05.025

    View details for Web of Science ID 000341456500029

  • Arterial Applanation Tonometry: Feasibility and Reproducibility in Children and Adolescents AMERICAN JOURNAL OF HYPERTENSION Lowenthal, A., Evans, J. M., Punn, R., Nourse, S. E., Vu, C. N., Popat, R. A., Tierney, E. S. 2014; 27 (9): 1218-1224


    Aortic pulse wave velocity (PWV) and augmentation index (AIx) are markers of vascular health and have recently been used in pediatric clinical trials. However, there are limited data on standardization of these measurements in pediatrics. The objective of this study was to prospectively test the feasibility and reproducibility of PWV and AIx in children and adolescents.We performed arterial tonometry on 2 different days within 2 weeks in 40 healthy subjects aged 10-19 years. PWV and AIx were measured in triplicate on each visit.The visits were separated by a mean of 3.08±3.7 days. We obtained PWV in 77 of 80 (96%) visits and AIx in 76 of 80 (95%) visits in triplicate. Intraclass correlation coefficients (ICCs) for PWV were 0.61 (95% confidence interval (CI) = 0-0.86) when at least 2 measurements and 0.92 (95% CI = 0-1) when 3 measurements were obtained at each visit that met the quality criteria established for adults by the manufacturer (n = 17 and 3 paired visits, respectively). For AIx, ICCs were 0.78 (95% CI = 0.58-0.88) and 0.81 (95% CI = 0.63-0.90) when measurements with an operator index ≥80, a measure of the quality of the waveform, were included (n = 39 and 36 paired visits, respectively).Arterial applanation tonometry is feasible and reproducible in healthy children and adolescents. AIx has excellent intervisit reproducibility, whereas the intervisit reproducibility of PWV relies on acquisition of multiple measurements that meet quality criteria established for adults. These results have implications for the methodology of future pediatric clinical trials in a population at increasingly higher risk for premature atherosclerosis.

    View details for DOI 10.1093/ajh/hpu034

    View details for Web of Science ID 000342853700013

  • Changes in health status among aging survivors of pediatric upper and lower extremity sarcoma: a report from the childhood cancer survivor study. Archives of physical medicine and rehabilitation Marina, N., Hudson, M. M., Jones, K. E., Mulrooney, D. A., Avedian, R., Donaldson, S. S., Popat, R., West, D. W., Fisher, P., Leisenring, W., Stovall, M., Robison, L. L., Ness, K. K. 2013; 94 (6): 1062-1073


    To evaluate health status and participation restrictions in survivors of childhood extremity sarcomas.Members of the Childhood Cancer Survivor Study cohort with extremity sarcomas who completed questionnaires in 1995, 2003, or 2007 were included.Cohort study of survivors of extremity sarcomas.Childhood extremity sarcoma survivors (N=1094; median age at diagnosis, 13y (range, 0-20y); current age, 33y (range, 10-53y); 49% male; 87.5% white; 75% had lower extremity tumors) who received their diagnosis and treatment between 1970 and 1986.Not applicable.Prevalence rates for poor health status in 6 domains and 5 suboptimal social participation categories were compared by tumor location and treatment exposure with generalized estimating equations adjusted for demographic/personal factors and time/age.In adjusted models, when compared with upper extremity survivors, lower extremity survivors had an increased risk of activity limitations but a lower risk of not completing college. Compared with those who did not have surgery, those with limb-sparing (LS) and upper extremity amputations (UEAs) were 1.6 times more likely to report functional impairment, while those with an above-the-knee amputation (AKA) were 1.9 times more likely to report functional impairment. Survivors treated with LS were 1.5 times more likely to report activity limitations. Survivors undergoing LS were more likely to report inactivity, incomes <$20,000, unemployment, and no college degree. Those with UEAs more likely reported inactivity, unmarried status, and no college degree. Those with AKA more likely reported no college degree. Treatment with abdominal irradiation was associated with an increased risk of poor mental health, functional impairment, and activity limitation.Treatment of lower extremity sarcomas is associated with a 50% increased risk for activity limitations; upper extremity survivors are at a 10% higher risk for not completing college. The type of local control influences health status and participation restrictions. Both of these outcomes decline with age.

    View details for DOI 10.1016/j.apmr.2013.01.013

    View details for PubMedID 23380347

  • Common iliac vein stenosis: a risk factor for oral contraceptive-induced deep vein thrombosis 36th Annual Scientific Meeting of the Society-of-Interventional-Radiology Chan, K. T., Tye, G. A., Popat, R. A., Kuo, W. T., Unver, K., Kothary, N., Sze, D. Y., Hofmann, L. V. MOSBY-ELSEVIER. 2011


    The objective of the study was to determine whether women with significant left common iliac vein stenosis who also use combined oral contraceptives (COCs) have a combined likelihood of deep vein thrombosis (DVT) greater than each independent risk.This was a case-control study comparing 35 women with DVT against 35 age-matched controls. Common iliac vein diameters were measured from computed tomography and magnetic resonance imaging. Logistic regression modeling was used with adjustment for risk factors.DVT was associated with COC use (P = .022) and with increasing degrees of common iliac vein stenosis (P = .004). Compared with women without venous stenosis or COC use, the odds of DVT in women with a 70% venous stenosis who also use COCs was associated with a 17-fold increase (P = .01).Venous stenosis and COC use are independent risk factors for DVT. Women concurrently exposed to both have a multiplicative effect resulting in an increased risk of DVT. We recommend further studies to investigate this effect and its potential clinical implications.

    View details for DOI 10.1016/j.ajog.2011.06.100

    View details for PubMedID 21893308



    Cognitive aging affects episodic memory and executive functions, and these vulnerable domains are postulated to be modulated by endogenous and exogenous estrogen exposures. In midlife and late-life women without dementia, estrogen effects on cognition can be examined through associations with concentrations of serum estrone and estradiol and through clinical trials of estrogen-containing hormone therapy. To this end, we reviewed published studies including at least 100 women (larger studies are less prone to publication bias) addressing associations between estrogen levels and performance on neuropsychological tests of episodic memory or executive functions (including working memory; seven studies), or that reported results of placebo-controlled clinical trials of hormone therapy with objective measures within these cognitive domains (eight studies). Results were considered separately for midlife and late-life (age≥65 years) women. There were no consistent associations between endogenous serum estrogen concentrations and episodic memory or executive functions in naturally menopausal midlife women or in older postmenopausal women. Clinical trial findings suggested no substantial impact of exogenous estrogens on episodic memory or executive functions over time frames of up to several years. A quantitative synthesis of clinical trial results supported the inference of absence of effect. This overall conclusion of no substantial effect on episodic memory or executive functions might reassure women concerned by potential adverse cognitive consequences of menopause or of relatively short-term midlife hormone therapy. There was no apparent window of opportunity during which exogenous hormones might benefit near-term cognition, but included studies provided limited power to identify such a window. Conclusions are tempered by small numbers of studies, imprecise estimates of long-term estrogen exposures, and narrow range of neuropsychological tests. Long-term (late-life) cognitive consequence of midlife estrogen exposures are poorly addressed by current data, as are cognitive consequences of surgical menopause and cognitive consequences of exogenous estrogens during the menopause transition. This article is part of a Special Issue entitled: Neuroactive Steroids: Focus on Human Brain.

    View details for DOI 10.1016/j.neuroscience.2011.05.059

    View details for Web of Science ID 000295749300013

    View details for PubMedID 21664950

  • Association of DRD2 and DRD3 polymorphisms with Parkinson's disease in a multiethnic consortium JOURNAL OF THE NEUROLOGICAL SCIENCES McGuire, V., Van Den Eeden, S. K., Tanner, C. M., Kamel, F., Umbach, D. M., Marder, K., Mayeux, R., Ritz, B., Ross, G. W., Petrovitch, H., Topol, B., Popat, R. A., Costello, S., Manthripragada, A. D., Southwick, A., Myers, R. M., Nelson, L. M. 2011; 307 (1-2): 22-29


    To examine genetic associations of polymorphisms in the dopamine receptor D2 (DRD2) and D3 (DRD3) genes with risk of Parkinson's disease (PD).The study included 1325 newly diagnosed patients with PD and 1735 controls from a consortium of five North American case-control studies. We collected risk factor information by in-person or telephone interview. Six DRD2 and two DRD3 polymorphisms were genotyped using a common laboratory. Odds ratios were estimated using logistic regression.Among non-Hispanic whites, homozygous carriers of Taq1A DRD2 (rs1800497) polymorphism had an increased risk of PD compared to homozygous wildtype carriers (OR=1.5, 95% CI 1.0-2.3). In contrast, the direction of association for Taq1A polymorphism was opposite for African-Americans, showing an inverse association with PD risk (OR=0.10, 95% CI 0.2-0.7). Among white Hispanics who carried two alleles, the Ser9Gly DRD3 (rs6280) polymorphism was associated with a decreased risk of PD (OR=0.4, 95% CI 0.2-0.8). The inverse association of smoking with PD risk was not modified by any of the DRD2 or DRD3 polymorphisms.DRD2 polymorphisms are unlikely to be true disease-causing variants; however, three DRD2 polymorphisms (including Taq1A) may be in linkage disequilibrium with possible disease associated variants in the DRD2-ANKK1-NCAM1-TTC12 gene cluster.

    View details for DOI 10.1016/j.jns.2011.05.031

    View details for PubMedID 21663922

  • Understanding Study Design PM&R Sainani, K. L., Popat, R. A. 2011; 3 (6): 573-577

    View details for DOI 10.1016/j.pmrj.2011.04.001

    View details for Web of Science ID 000305437700010

    View details for PubMedID 21665169

  • Coffee, ADORA2A, and CYP1A2: the caffeine connection in Parkinson's disease EUROPEAN JOURNAL OF NEUROLOGY Popat, R. A., Van Den Eeden, S. K., Tanner, C. M., Kamel, F., Umbach, D. M., Marder, K., Mayeux, R., Ritz, B., Ross, G. W., Petrovitch, H., Topol, B., McGuire, V., Costello, S., Manthripragada, A. D., Southwick, A., Myers, R. M., Nelson, L. M. 2011; 18 (5): 756-765


    In 1-methyl-4-phenyl 1,2,3,6-tetrahydropyridine animal models of Parkinson's disease (PD), caffeine protects neurons by blocking the adenosine receptor A2A (ADORA2A). Caffeine is primarily metabolized by cytochrome P450 1A2 (CYP1A2). Our objective was to examine whether ADORA2A and CYP1A2 polymorphisms are associated with PD risk or modify the caffeine-PD association.Parkinson's Epidemiology and Genetic Associations Studies in the United States (PEGASUS) included five population-based case-control studies. One laboratory genotyped four ADORA2A and three CYP1A2 polymorphisms in 1325 PD cases and 1735 age- and sex-matched controls. Information regarding caffeine (coffee) consumption and other lifestyle factors came from structured in-person or telephone interviews. Odds ratios (OR) and 95% confidence intervals (CI) were estimated using logistic regression.Two ADORA2A polymorphisms were inversely associated with PD risk - rs71651683, a 5' variant (adjusted allelic OR = 0.51, 95% CI 0.33-0.80, permutation-adjusted P = 0.015) and rs5996696, a promoter region variant (adjusted OR for AC and CC genotypes compared with the AA wild-type genotype were 0.76 (95% CI 0.57-1.02) and 0.37 (95% CI 0.13-1.01), respectively (permutation-adjusted P for trend = 0.04). CYP1A2 polymorphisms were not associated with PD risk; however, the coffee-PD association was strongest among subjects homozygous for either variant allele rs762551 (P(interaction) = 0.05) or rs2470890 (P(interaction) = 0.04).In this consortium study, two ADORA2A polymorphisms were inversely associated with PD risk, but there was weak evidence of interaction with coffee consumption. In contrast, the coffee-PD association was strongest among slow metabolizers of caffeine who were homozygous carriers of the CYP1A2 polymorphisms.

    View details for DOI 10.1111/j.1468-1331.2011.03353.x

    View details for PubMedID 21281405

  • Common Iliac Vein Stenosis and Risk of Symptomatic Pulmonary Embolism: An Inverse Correlation JOURNAL OF VASCULAR AND INTERVENTIONAL RADIOLOGY Chan, K. T., Popat, R. A., Sze, D. Y., Kuo, W. T., Kothary, N., Louie, J. D., Hovsepian, D. M., Hwang, G. L., Hofmann, L. V. 2011; 22 (2): 133-141


    To test the hypothesis that a common iliac vein (CIV) stenosis may impair embolization of a large deep venous thrombosis (DVT) to the lungs, decreasing the incidence of a symptomatic pulmonary embolism (PE).Between January 2002 and August 2007, 75 patients diagnosed with unilateral DVT were included in a single-institution case-control study. Minimum CIV diameters were measured 1 cm below the inferior vena cava (IVC) bifurcation on computed tomography (CT) images. A significant stenosis in the CIV ipsilateral to the DVT was defined as having either a diameter 4 mm or less or a greater than 70% reduction in lumen diameter. A symptomatic PE was defined as having symptoms and imaging findings consistent with a PE. The odds of symptomatic PE versus CIV stenosis were assessed using logistic regression models. The associations between thrombus location, stenosis, and symptomatic PE were assessed using a stratified analysis.Of 75 subjects, 49 (65%) presented with symptomatic PE. There were 17 (23%) subjects with a venous lumen 4 mm or less and 12 (16%) subjects with a greater than 70% stenosis. CIV stenosis of 4 mm or less resulted in a decreased odds of a symptomatic PE compared with a lumen greater than 4 mm (odds ratio [OR] 0.17, P = .011), whereas a greater than 70% stenosis increased the odds of DVT involving the CIV (OR 7.1, P = .047).Among patients with unilateral DVT, those with an ipsilateral CIV lumen of 4 mm or less have an 83% lower risk of developing symptomatic PE compared with patients with a CIV lumen greater than 4 mm.

    View details for DOI 10.1016/j.jvir.2010.10.009

    View details for PubMedID 21276911

  • Familial Aggregation of Parkinson's Disease in a Multiethnic Community-Based Case-Control Study MOVEMENT DISORDERS Shino, M. Y., McGuire, V., Van Den Eeden, S. K., Tanner, C. M., Popat, R., Leimpeter, A., Bernstein, A. L., Nelson, L. M. 2010; 25 (15): 2587-2594


    To assess the familial aggregation of Parkinson's disease (PD), we compared the cumulative incidence of PD among first-degree relatives of PD cases and controls. We identified newly diagnosed patients with PD (n = 573) during 1994 to 1995 within Kaiser Permanente Medical Care Program of Northern California and recruited 496 cases (87%) for the case-control study. Of 720 eligible controls matched by birth year and sex to cases, 541 (75%) agreed to participate. Information on family history of PD and other neurodegenerative diseases was obtained by in-person structured interview. We used the reconstructed cohort approach that provides a better estimate of the risk. The cumulative incidence of PD was significantly higher among relatives of PD patients compared with relatives of controls (2.0 vs. 0.7%; relative risk (RR) = 3.4, 95% confidence interval (CI) 1.9-5.9; P = 0.0001). The degree of familial aggregation was higher among first-degree relatives of Hispanic PD cases compared with Hispanic controls (3.7% vs. 0.4%; RR = 8.5, 95% CI 1.0-68.9) than it was among non-Hispanic Caucasian cases and controls (2.0% vs. 0.8%; RR = 2.7, 95% CI 1.5-5.1; P = 0.02). The familial aggregation of PD was stronger among the siblings of PD cases (RR = 5.4, 95% CI 1.8-16.0) than among parents (RR = 2.7, 95% CI 1.3-5.2). The incidence and familial aggregation of PD is highest among Hispanics, warranting further studies of genetic and environmental risk factors in the Hispanic population.

    View details for DOI 10.1002/mds.23361

    View details for Web of Science ID 000284060600016

    View details for PubMedID 20842689

    View details for PubMedCentralID PMC2978761

  • Reliability and validity of two self-administered questionnaires for screening restless legs syndrome in population-based studies SLEEP MEDICINE Popat, R. A., Van Den Eeden, S. K., Tanner, C. M., Kushida, C. A., Rama, A. N., Black, J. E., Bernstein, A., Kasten, M., Chade, A., Leimpeter, A., Cassidy, J., McGuire, V., Nelson, L. M. 2010; 11 (2): 154-160


    A reliable and valid questionnaire for screening restless legs syndrome (RLS) is essential for determining accurate estimates of disease frequency. In a 2002 NIH-sponsored workshop, experts suggested three mandatory questions for identifying RLS in epidemiologic studies. We evaluated the reliability and validity of this RLS-NIH questionnaire in a community-based sample and concurrently developed and evaluated the utility of an expanded screening questionnaire, the RLS-EXP.The study was conducted at Kaiser Permanente of Northern California and the Stanford University Sleep Clinic. We evaluated test-retest reliability in a random sample of subjects with prior physician-assigned RLS (n=87), subjects with conditions frequently misclassified as RLS (n=31), and healthy subjects (n=9). Validity of both instruments was evaluated in a random sample of 32 subjects, and in-person examination by two RLS specialists was used as the gold standard.For the first three RLS-NIH questions, the kappa statistic for test-retest reliability ranged from 0.5 to 1.0, and sensitivity and specificity was 86% and 45%, respectively. For the subset of five questions on RLS-EXP that encompassed cardinal features for diagnosing RLS, kappas were 0.4-0.8, and sensitivity and specificity were 81% and 73%, respectively.Sensitivity of RLS-NIH is good; however, the specificity of the instrument is poor when examined in a sample that over-represents subjects with conditions that are commonly misclassified as RLS. Specificity can be improved by including separate questions on cardinal features, as used in the RLS-EXP, and by including a few questions that identify RLS mimics, thereby reducing false positives.

    View details for DOI 10.1016/j.sleep.2009.01.012

    View details for Web of Science ID 000275584500009

    View details for PubMedID 20089446

  • Short- and Long-Term Outcomes of Necrotizing Enterocolitis in Infants With Congenital Heart Disease PEDIATRICS Pickard, S. S., Feinstein, J. A., Popat, R. A., Huang, L., Dutta, S. 2009; 123 (5): E901-E906


    Congenital heart disease is a significant risk factor for necrotizing enterocolitis in the term infant. We compared the short- and long-term necrotizing enterocolitis-specific outcomes of infants with congenital heart disease with those of neonates without congenital heart disease.A retrospective study of 202 patients with necrotizing enterocolitis treated at our center from May 1999 to August 2007 was conducted. Infants with necrotizing enterocolitis were grouped according to the presence (n = 76) or absence (n = 126) of congenital heart disease. Demographic and necrotizing enterocolitis-specific outcomes were recorded. The groups were compared by nonparametric and chi(2) analyses. Univariate and multivariate odds ratios were determined for each outcome.The average birth weight and gestational age of the 2 groups were not significantly different. The initial necrotizing enterocolitis severity, as determined by Bell stage, was less for necrotizing enterocolitis subjects with congenital heart disease compared with those without congenital heart disease. When controlling for birth weight and gestational age, the congenital heart disease group had decreased risk of perforation, need for a bowel operation, strictures, need for a stoma, sepsis, and short bowel syndrome compared with the non-congenital heart disease group. Although not statistically significant, subjects with congenital heart disease had a trend toward decreased risk of death from necrotizing enterocolitis, recurrent necrotizing enterocolitis, and need for peritoneal drainage.Infants with congenital heart disease and necrotizing enterocolitis have decreased risk of major short- and long-term negative outcomes associated with necrotizing enterocolitis compared with neonates without congenital heart disease. Differences in initial severity, range of age at diagnosis, and prognoses between subjects with necrotizing enterocolitis with and without cardiac disease suggest that necrotizing enterocolitis in the cardiac patient is a distinct disease process and should be labeled cardiogenic necrotizing enterocolitis.

    View details for DOI 10.1542/peds.2008-3216

    View details for PubMedID 19403484

  • Effect of non-steroidal anti-inflammatory medications on the risk of amyotrophic lateral sclerosis AMYOTROPHIC LATERAL SCLEROSIS Popat, R. A., Tanner, C. M., Van Den Eeden, S. K., Bernstein, A. L., Bloch, D. A., Leimpeter, A., McGuire, V., Nelson, L. M. 2007; 8 (3): 157-163


    Inflammatory processes may be involved in the pathogenesis of amyotrophic lateral sclerosis (ALS). We examined the association of non-steroidal anti-inflammatory drugs (NSAIDs) with the risk of ALS in case-control study of incident cases (n = 111) conducted within the Kaiser Permanente Medical Care Program of Northern California during the years 1996-2000. Controls (n = 258) randomly selected from the same population were frequency matched by age and gender to the ALS cases. Information regarding use of NSAIDs (non-aspirin and aspirin) and three classes of 'control' medications was collected by in-person structured interview. Subjects who used medication at least twice a week for at least a month were classified as 'ever users'. Multivariable logistic regression models were adjusted for age, gender, history of osteoarthritis/rheumatoid arthritis and pain, and other medication use. Overall, there was no association between NSAID use and ALS; however, some sex differences were noted for non-aspirin NSAID use. Among men, non-aspirin NSAID use was associated with a two-fold increased risk of ALS (adjusted odds ratio (OR) 2.0, 95% confidence interval (CI) 1.0-3.9), whereas among women, non-aspirin NSAID use was not associated with increased ALS risk (adjusted OR 0.5, 95% CI 0.2-1.2). ALS risk was not associated with aspirin use or with 'control' medications. This study did not find any evidence to suggest that NSAID use reduces the risk of ALS. The observed sex differences with non-aspirin NSAID use could be due to chance or an unmeasured confounder.

    View details for DOI 10.1080/17482960601179456

    View details for Web of Science ID 000246949600004

    View details for PubMedID 17538777

  • Clinical and demographic predictors of long-term disability in patients with relapsing-remitting multiple sclerosis - A systematic review ARCHIVES OF NEUROLOGY Langer-Gould, A., Popat, R. A., Huang, S. M., Cobb, K., Fontoura, P., Gould, M. K., Nelson, L. M. 2006; 63 (12): 1686-1691


    To identify clinical and demographic factors associated with long-term disability in patients with relapsing-remitting multiple sclerosis.We searched the MEDLINE (1966-May 2005), EMBASE, CINAHL, Cochrane, and PsycINFO computerized databases, and reviewed reference lists of retrieved articles.We included studies that examined predictors of long-term disability in patients with relapsing-remitting multiple sclerosis. We excluded studies that did not distinguish relapsing-remitting multiple sclerosis from primary progressive multiple sclerosis, enrolled fewer than 40 subjects, observed subjects for less than 5 years, or collected follow-up information in less than 80% of the inception cohort.Two reviewers assessed study quality in 4 domains: cohort assembly, definitions and assessments of prognostic factors and outcomes, and statistical methods. One reviewer extracted data on the direction, magnitude, precision, and statistical significance of the effect of each predictor on prognosis.Heterogeneity of study designs precluded us from pooling the results of 27 eligible studies. Study quality was limited by cross-sectional design, enrollment of prevalent cases from referral centers, and lack of multivariate adjustment. Sphincter symptoms at onset (hazard ratio, 1.1-3.1), incomplete recovery from the first attack (hazard ratio, 1.3-3.3), and a short interval between the first and second attack (hazard ratio, 1.6-1.9) were most strongly and consistently associated with poor prognosis. Other factors widely believed to be of prognostic importance, including sex and age at onset, demonstrated inconsistent or weak effects on prognosis.The most robust predictors of long-term physical disability in relapsing-remitting multiple sclerosis are sphincter symptoms at onset and early disease course outcomes. These factors can be used to guide treatment decisions for drugs with significant toxicities.

    View details for Web of Science ID 000242733000003

    View details for PubMedID 17172607

  • Effect of reproductive factors and postmenopausal hormone use on the risk of amyotrophic lateral sclerosis NEUROEPIDEMIOLOGY Popat, R. A., Van Den Eeden, S. K., Tanner, C. M., Bernstein, A. L., Bloch, D. A., Leimpeter, A., McGuire, V., Nelson, L. M. 2006; 27 (3): 117-121


    To examine the associations of reproductive factors and postmenopausal hormone use with the risk of amyotrophic lateral sclerosis (ALS) among women.This case-control study was conducted within the Kaiser Permanente Medical Care Program (KPMCP) of Northern California during the years 1996-2000. Among the 193 postmenopausal women, 62 were incident ALS cases and 131 were controls randomly selected from KPMCP members and frequency matched by age and respondent type (self versus proxy) to the cases. Statistical analyses were carried out using logistic regression.Reproductive factors such as age at menarche, age at final menstrual period, parity, oral contraceptive use, and type of menopause (natural vs. hysterectomy with or without oophorectomy) were not associated with risk of ALS. Postmenopausal hormone use was positively, but not significantly, associated with the risk of ALS (adjusted OR 1.9, 95% CI 0.9-3.8).Reproductive factors were not associated with ALS risk. There is no evidence that suggests a protective effect of postmenopausal hormone use against the development of ALS. However, due to insufficient power, we cannot rule out a possible increase in ALS risk associated with postmenopausal hormone use.

    View details for DOI 10.1159/000095550

    View details for Web of Science ID 000241773900001

    View details for PubMedID 16946622

  • Effect of reproductive factors and postmenopausal hormone use on the risk of Parkinson disease NEUROLOGY Popat, R. A., Van Den Eeden, S. K., Tanner, C. M., McGuire, V., Bernstein, A. L., Bloch, D. A., Leimpeter, A., Nelson, L. M. 2005; 65 (3): 383-390


    Parkinson disease (PD) is less common in women possibly because of hormonal or reproductive influences. The objective of this study was to evaluate the associations of reproductive factors and postmenopausal hormone use with the risk of PD among postmenopausal women.Incident cases (n = 178) and randomly selected age-matched controls (n = 189) who were members of the Kaiser Permanente Medical Care Program (KPMCP) of Northern California participated in the study conducted during the years 1994 to 1995. Statistical analyses were carried out using logistic regression.The association of postmenopausal hormone use with PD risk depended on the type of menopause. Among women with history of a hysterectomy with or without an oophorectomy, estrogen use alone was associated with a 2.6-fold increased risk (adjusted odds ratio (OR) 2.6, 95% CI: 1.1 to 6.1) and significant trends in the risk of PD were observed with increasing duration of estrogen use, but disease risk was not influenced by recency of use. In contrast, among women with natural menopause, no increased risk of PD was observed with hormone use (estrogen alone or a combined estrogen-progestin regimen). Early age at final menstrual period (44 years or younger) was associated with reduction in risk (adjusted OR 0.5, 95% CI: 0.3 to 1.0). Age at menarche and parity were not associated with the risk of PD.Postmenopausal use of estrogen alone may increase the risk of Parkinson disease (PD) among women with a hysterectomy. Among women with natural menopause for whom the usual treatment is combined estrogen-progestin therapy, no increased risk of PD was observed.

    View details for Web of Science ID 000231067200010

    View details for PubMedID 16087902

  • Biomechanical analysis of failed sit-to-stand. IEEE transactions on rehabilitation engineering Riley, P. O., Krebs, D. E., Popat, R. A. 1997; 5 (4): 353-359


    Background sit-to-stand (STS) failure is a transient loss of balance that can engender falls among elders. The purpose of this paper is to describe the mechanisms whereby failed STS differs from successful STS. The authors compared successful STS from 11 normal elders to 20 "sitback" and 20 "step" type failed STS's in 13 subjects. Kinematic and kinetic data were incorporated into our 11-segment whole body model to estimate the net joint forces and torques and body segment momenta. Significant between group differences in the magnitude and timing of momentum generation and dissipation, knee extensor torques and the magnitude of the vertical ground reaction force were identified. Both types of failed sit-to-stand maneuvers are less energetic than successful rises. STS failures might result from either weakness or balance control and coordination impairment, or both, resulting in an insufficiently energetic effort. Further research is required to differentiate between these two possible sources of impairment. Determining the root cause of functional limitations is necessary to develop effective interventions.

    View details for PubMedID 9422460

  • Rehabilitation of balance in two patients with cerebellar dysfunction PHYSICAL THERAPY GILLBODY, K. M., Popat, R. A., Parker, S. W., Krebs, D. E. 1997; 77 (5): 534-552


    The treatment of two patients with cerebellar dysfunction is described. One patient was a 36-year-old woman with a 7-month history of dizziness and unsteadiness following surgical resection of a recurrent pilocystic astrocytoma located in the cerebellar vermis. The other patient was a 48-year-old man with cerebrotendinous xanthomatosis (CTX) and diffuse cerebellar atrophy, and a 10-year history of progressive gait and balance difficulties. Each patient was treated with a 6-week course of physical therapy that emphasized the practice of activities that challenged stability. The patient with the cerebellar tumor resection also performed eye-head coordination exercises. Each patient had weekly therapy and performed selected balance retraining exercises on a daily basis at home. Measurements taken before and after treatment for each patient included self-perception of symptoms, clinical balance tests, and stability during selected standing and gait activities; for the patient with the cerebellar tumor resection, vestibular function tests and posturography were also performed. Both patients reported improvements in symptoms and demonstrated similar improvements on several kinematic indicators of stability during gait. The patient with the cerebellar tumor resection improved on posturography following treatment, whereas the patient with CTX improved on clinical balance tests. This case report describes two individualized treatment programs and documents functional improvements in two patients with different etiologies, durations, and clinical presentations of cerebellar dysfunction. The outcomes suggest that patients with cerebellar lesions, acute or chronic, may be able to learn to improve their postural stability.

    View details for Web of Science ID A1997WY50200008

    View details for PubMedID 9149763



    We studied the relationship between kinematically unconstrained activities of daily living (ADL) tasks and a kinematically constrained task in above-elbow (AE) amputee subjects using myoelectrically controlled prostheses. Four men, 24 to 49 years old, with unilateral AE amputation wore a prosthesis interfaced to a programmable controller to emulate two different elbow control schemes, conventional velocity and a new "natural" controller. Subjects were timed during three ADL tasks--cutting meat, donning socks, and rolling dough--with both controllers. The prosthesis emulator was then connected to a crank device with a handle, and the subjects turned the crank from bottom to top positions in a vertical plane using each controller. Synergistic shoulder-elbow joint coordination required for crank turning was quantified as the maximum slope of the change in elbow torque versus the change in crank-angle. Performance between the two controllers differed significantly for the crank test but not for ADL tasks. One subject did not complete all crank turning tests. Positive canonical correlation of 0.77 was found between time and crank domain measures. We conclude that biomechanical assessments should be integrated with time-based clinical tests to comprehensively evaluate performance of AE amputee subjects with a myoelectric device.

    View details for Web of Science ID A1993LM07900010

    View details for PubMedID 8328894