I am passionate about gut health and strive to provide the best care to my patients. I specialize in complex motility disorders of the gastrointestinal tract. My areas of clinical expertise include achalasia, dysphagia, eosinophilic esophagitis, gastroesophageal reflux disease, gastroparesis, functional dyspepsia, irritable bowel syndrome, and pelvic floor dysfunction. I also see patients in need of fecal microbiota transplant for recurrent C. difficile infection.

Clinical Focus

  • Gastroenterology
  • Neurogastroenterology
  • Dysphagia
  • Eosinophilic Esophagitis
  • Achalasia
  • Irritable Bowel Syndrome
  • Constipation
  • Diarrhea
  • Celiac Disease
  • Pelvic Floor Dysfunction
  • Gastroparesis
  • Scleroderma Bowel Disease

Academic Appointments

Administrative Appointments

  • Clinical Assistant Professor, Stanford Healthcare (2016 - Present)

Honors & Awards

  • Johnson & Johnson Global Health Scholars Program, Stanford University (2012)
  • PHI BETA KAPPA, Massachusetts Institute of Technology (2004)

Boards, Advisory Committees, Professional Organizations

  • Member, American Gastroenterology Association (2016 - Present)
  • Member, American College of Gastroenterology (2014 - Present)
  • Member, American Society for Gastroenterology Endoscopy (2013 - Present)

Professional Education

  • Residency: Stanford University Internal Medicine Residency (2013) CA
  • Internship: Stanford University Internal Medicine Residency (2011) CA
  • Medical Education: Perelman School of Medicine University of Pennsylvania (2010) PA
  • Board Certification: American Board of Internal Medicine, Gastroenterology (2016)
  • Fellowship: Stanford Hospital and Clinics (2016) CA
  • Board Certification: American Board of Internal Medicine, Internal Medicine (2013)
  • Board Certifications, American Board of Internal Medicine, Gastroenterology (2016)
  • Fellowship, Stanford Health Care, Gastroenterology and Hepatology (2016)
  • Residency, Stanford Health Care (2013)
  • BS, Massachusetts Institute of Technology, Biology (2004)

Community and International Work

  • University City Health Coalition Free Medical Clinic, Philadelphia, PA

    Populations Served


    Ongoing Project


    Opportunities for Student Involvement


  • Arbor Free Clinic, East Menlo Park, CA

    Populations Served


    Ongoing Project


    Opportunities for Student Involvement


  • Pacific Free Pain Clinic, San Jose, CA

    Populations Served


    Ongoing Project


    Opportunities for Student Involvement


2023-24 Courses

Graduate and Fellowship Programs

  • Gastroenterology & Hepatology (Fellowship Program)

All Publications

  • Use of a footstool improves rectal balloon expulsion in some patients with defecatory disorders. Neurogastroenterology and motility Ulsh, L., Halawi, H., Triadafilopoulos, G., Gurland, B., Nguyen, L., Garcia, P., Sonu, I., Fernandez-Becker, N., Becker, L., Sheth, V., Neshatian, L. 2024: e14781


    Whether patients with defecatory disorders (DDs) with favorable response to a footstool have distinctive anorectal pressure characteristics is unknown. We aimed to identify the clinical phenotype and anorectal pressure profile of patients with DDs who benefit from a footstool.This is a retrospective review of patients with high resolution anorectal manometry (HR-ARM) and balloon expulsion test (BET) from a tertiary referral center. BET was repeated with a 7-inch-high footstool in those who failed it after 120 s. Data were compared among groups with respect to BET results.Of the 667 patients with DDs, a total of 251 (38%) had failed BET. A footstool corrected BET in 41 (16%) of those with failed BET. Gender-specific differences were noted in anorectal pressures, among patients with and without normal BET, revealing gender-based nuances in pathophysiology of DDs. Comparing patients who passed BET with footstool with those who did not, the presence of optimal stool consistency, with reduced instances of loose stools and decreased reliance on laxatives were significant. Additionally, in women who benefited from a footstool, lower anal pressures at rest and simulated defecation were observed. Independent factors associated with a successful BET with a footstool in women included age <50, Bristol 3 or 4 stool consistency, lower anal resting pressure and higher rectoanal pressure gradient.Identification of distinctive clinical and anorectal phenotype of patients who benefited from a footstool could provide insight into the factors influencing the efficacy of footstool utilization and allow for an individualized treatment approach in patients with DDs.

    View details for DOI 10.1111/nmo.14781

    View details for PubMedID 38488172

  • Cromolyn Reduces Symptoms in Patients With Irritable Bowel Syndrome, Functional Dyspepsia, or Gastroparesis Karhu, E., Linda Anh Nguyen, Sonu, I., Neshatian, L., Gottfried-Blackmore, A., Fernandez-Becker, N., Spencer, S. LIPPINCOTT WILLIAMS & WILKINS. 2023: S492
  • Prevalence and Predictive Factors of Small Intestinal Bacterial Overgrowth in Patients With Chronic Fatigue Syndrome Karhu, E., Neshatian, L., Fass, O., Sonu, I., Nguyen, L. LIPPINCOTT WILLIAMS & WILKINS. 2023: S1351-S1352
  • Development and Validation of a Machine Learning System to Identify Reflux Events in Esophageal 24-hour pH/Impedance Studies. Clinical and translational gastroenterology Zhou, M. J., Zikos, T., Goel, K., Goel, K., Gu, A., Re, C., Rodriguez, D., Clarke, J. O., Garcia, P., Fernandez-Becker, N., Sonu, I., Kamal, A., Sinha, S. R. 2023


    INTRODUCTION: Esophageal 24-hour pH/impedance testing is routinely performed to diagnose gastroesophageal reflux disease (GERD). Interpretation of these studies is time-intensive for expert physicians and has high inter-reader variability. There are no commercially available machine learning tools to assist with automated identification of reflux events in these studies.METHODS: A machine learning system to identify reflux events in 24-hour pH/impedance studies was developed, which included an initial signal processing step and a machine learning model. Gold standard reflux events were defined by a group of expert physicians. Performance metrics were computed to compare the machine learning system, current automated detection software (Reflux Reader v6.1), and an expert physician reader.RESULTS: The study cohort included 45 patients (20/5/20 patients in the training/validation/test sets, respectively). Mean age was 51 (standard deviation [SD] 14.5) years, 47% of patients were male, and 78% of studies were performed off proton pump inhibitor (PPI). Comparing the machine learning system vs. current automated software vs. expert physician reader, AUC was 0.87 (95% CI 0.85-0.89) vs. 0.40 (95% CI 0.37-0.42) vs. 0.83 (95% CI 0.81-0.86), respectively; sensitivity was 68.7% vs. 61.1% vs. 79.4%, respectively; and specificity was 80.8% vs. 18.6% vs. 87.3%, respectively.DISCUSSION: We trained and validated a novel machine learning system to successfully identify reflux events in 24-hour pH/impedance studies. Our model performance was superior to that of existing software and comparable to that of a human reader. Machine learning tools could significantly improve automated interpretation of pH/impedance studies.

    View details for DOI 10.14309/ctg.0000000000000634

    View details for PubMedID 37578060

  • The integrated relaxation pressure may not be an appropriate gold standard for deglutitive relaxation due to reliance on a single intragastric reference sensor. Neurogastroenterology and motility : the official journal of the European Gastrointestinal Motility Society Fass, O. Z., Regalia, K. A., Sweatt, A. J., Nandwani, M. C., Zikos, T. A., Fernandez-Becker, N. Q., Nguyen, L. A., Sonu, I. S., Triadafilopoulos, G., Clarke, J. O. 2023: e14635


    BACKGROUND: Integrated relaxation pressure (IRP) calculation depends on the selection of a single gastric reference sensor. Variable gastric pressure readings due to sensor selection can lead to diagnostic uncertainty. This study aimed to examine the effect of gastric reference sensor selection on IRP measurement and diagnosis.METHODS: We identified high-resolution manometry (HRM) conducted between January and November 2017 with at least six intragastric reference sensors. IRP measurements and Chicago Classification 3.0 (CCv3) diagnoses were obtained for each of six gastric reference sensors. Studies were categorized as "stable" (no change in diagnosis) or "variable" (change in diagnosis with gastric reference selection). Variable diagnoses were further divided into "variable normal/dysmotility" (≥1 normal IRP measurement and≥1 CCv3 diagnosis), or "variable dysmotility" (≥1 CCv3 diagnosis, only elevated IRP measurements). Bland-Altman plots were used to compare IRP measurements within HRM studies.KEY RESULTS: The analysis included 100 HRM studies, among which 18% had variable normal/dysmotility, and 10% had variable dysmotility. The average IRP difference between reference sensors was 6.7mmHg for variable normal/dysmotility and 5.9mmHg for variable dysmotility. The average difference between the proximal-most and distal-most sensors was -1.52mmHg (lower limit of agreement -10.03mmHg, upper limit of agreement 7.00mmHg).CONCLUSIONS & INFERENCES: IRP values can vary greatly depending on the reference sensor used, leading to inconsistent diagnoses in 28% of HRM studies. Choosing the correct gastric reference sensor is crucial for accurate test results and avoiding misdiagnosis. Standardization of reference sensor selection or supportive testing for uncertain results should be considered.

    View details for DOI 10.1111/nmo.14635

    View details for PubMedID 37357376

  • Delivery of Fecal Material to Terminal Ileum Is Associated with Long-Term Success of Fecal Microbiota Transplantation. Digestive diseases and sciences Weingarden, A. R., Treiger, O., Ulsh, L., Limketkai, B., Goldenberg, D., Okafor, P., Sonu, I., Stollman, N., Neshatian, L. 2022


    BACKGROUND: Fecal microbiota transplantation (FMT) is a highly effective treatment for recurrent Clostridioides difficile infection (CDI). However, 10-20% of patients still fail to recover following FMT. There is a need to understand why these failures occur and if there are modifiable factors that can be addressed by clinicians performing FMT.AIMS: We sought to identify factors related to the FMT procedure itself which could impact FMT outcomes. We also aimed to identify patient demographics which might be associated with FMT outcomes and whether any factors were associated with early FMT failure compared to late CDI recurrence.METHODS: We performed a retrospective multicenter cohort analysis of FMT procedures between October 2005 and November 2020. We collected data on patient demographics, details of the FMT procedure, and procedure outcomes. Using univariate and multivariate regression, we evaluated whether these factors were associated with long-term FMT success, early FMT failure (less than 60days following procedure), or late CDI recurrence (more than 60days following procedure).RESULTS: Long-term success of FMT was strongly correlated with any delivery of stool to the terminal ileum (Odds Ratio [OR] 4.83, 95% confidence interval [CI] 1.359-17.167) and underlying neurologic disease (OR 8.012, 95% CI 1.041-61.684). Lower bowel prep quality was significantly associated with both early FMT failure (p=0.034) and late CDI recurrence (p=0.050).CONCLUSIONS: Delivery of stool to the terminal ileum is significantly associated with long-term success following FMT. This is a relatively safe practice which could easily be incorporated into the standard of care for colonoscopic FMT.

    View details for DOI 10.1007/s10620-022-07761-9

    View details for PubMedID 36372864

  • The Impact of Intermittent Fasting on Patients With Suspected Gastroesophageal Reflux Disease. Journal of clinical gastroenterology Jiang, Y., Sonu, I., Garcia, P., Fernandez-Becker, N. Q., Kamal, A. N., Zikos, T. A., Singh, S., Neshatian, L., Triadafilopoulos, G., Goodman, S. N., Clarke, J. O. 2022


    GOAL: The aim was to investigate the short-term impact of time restricted feeding on patients with suspected gastroesophageal reflux disease (GERD).BACKGROUND: Lifestyle modifications are often suggested, but the role of diet in GERD is unclear. Intermittent fasting is popular in the media and has demonstrated potential benefits with weight loss and inflammatory conditions as well as alterations in gastrointestinal hormones.STUDY: Patients who were referred for 96-hour ambulatory wireless pH monitoring off proton pump inhibitor to investigate GERD symptoms were screened for eligibility. Patients were instructed to maintain their baseline diet for the first 2 days of pH monitoring and switch to an intermittent fasting regimen (16 consecutive hour fast and 8h eating window) for the second 2 days. Objective measures of reflux and GERD symptom severity were collected and analyzed.RESULTS: A total of 25 participants were analyzed. 9/25 (36%) fully adhered to the intermittent fasting regimen, with 21/25 (84%) demonstrating at least partial compliance. Mean acid exposure time on fasting days was 3.5% versus 4.3% on nonfasting days. Intermittent fasting was associated with a 0.64 reduction in acid exposure time (95% CI: -2.32, 1.05). There was a reduction in GERD symptom scores of heartburn and regurgitation during periods of intermittent fasting (14.3 vs. 9.9; difference of -4.46, 95% CI: -7.6,-1.32).CONCLUSIONS: Initial adherence to time restricted eating may be difficult for patients. There is weak statistical evidence to suggest that intermittent fasting mildly reduces acid exposure. Our data show that short-term intermittent fasting improves symptoms of both regurgitation and heartburn.

    View details for DOI 10.1097/MCG.0000000000001788

    View details for PubMedID 36730832

  • Environmental Pollutants are Associated with Irritable Bowel Syndrome in a Commercially Insured Cohort of California Residents. Clinical gastroenterology and hepatology : the official clinical practice journal of the American Gastroenterological Association Okafor, P. N., Dahlen, A., Youssef, M., Olayode, A., Sonu, I., Neshatian, L., Nguyen, L., Charu, V. 2022


    BACKGROUND AND AIMS: Prior studies have linked environmental pollutants with gastrointestinal (GI) diseases. Here, we quantify the relationships between seven pollutants and the zip code-level incidence of irritable bowel syndrome (IBS), functional dyspepsia (FD), inflammatory bowel diseases (IBD), and eosinophilic esophagitis (EoE) in California.METHODS: Claims in Optum's Clinformatics Data Mart (CDM) were linked with environmental exposures in California, derived from CalEnviroScreen 3.0. We identified adult patients with new diagnoses of each GI disease, and estimated claims-derived, zip-code level disease incidence rates. Two study periods were considered: 2009-2014 (ICD-9 era) and 2016-2019 (ICD-10 era). Multivariable negative binomial regression models were used to test associations between seven pollutants (ozone, particulate matter <2.5 microns [PM2.5], diesel emissions, drinking water contaminants, pesticides, toxic releases from industrial facilities, traffic density) and zip-code level incidence of the GI diseases along with a negative control outcome, adjusting for numerous potential confounders.RESULTS: Zip code-level IBS incidence was associated with PM2.5 (p<0.001 in both eras) and airborne toxic releases from facilities (p<0.001 in both eras). An increase of 1 microgram/m3 in PM2.5 or 1% in toxic releases translates to an increase in the IBS incidence rate of about 0.02 cases per 100 person-years. Traffic density and drinking water contaminant exposures were also associated with increasing IBS incidence, but these associations were not significant in both eras. Similarly, exposure to PM2.5, drinking water contaminants and airborne toxic releases from facilities were associated with FD incidence, though not in both eras. No significant associations were noted between pollutants and IBD or EoE incidence.CONCLUSION: Exposure to PM2.5 and airborne toxic releases from facilities are associated with higher IBS incidence among a cohort of commercially-insured Californians. Environmental pollutant exposure was not associated with the incidence of IBD and EoE in this cohort.

    View details for DOI 10.1016/j.cgh.2022.09.025

    View details for PubMedID 36202347

  • The Effects of Intermittent Fasting on Gastroesophageal Reflux Disease Jiang, Y., Goodman, S., Sonu, I., Garcia, P., Fernandez-Becker, N., Kamal, A., Zikos, T., Singh, S., Neshatian, L., Triadafilopoulos, G., Clarke, J. LIPPINCOTT WILLIAMS & WILKINS. 2021: S214
  • GERD for the nongastroenterologist: successful evaluation, management, and lifestyle-based symptom control. Annals of the New York Academy of Sciences Stein, E., Sloan, J., Sonu, I., Kathpalia, P., Jodorkovsky, D. 2020


    Gastroesophageal reflux disease (GERD) is a complex disorder. Symptoms of heartburn can help find the disorder of GERD. pH testing is the mainstay of evaluation of symptoms, including 24-h and longer pH studies to detect pathologic acid exposure. The use of proton pump inhibitor (PPI) therapy for approved indications is helpful for both symptomatic relief and esophagitis healing in the majority of patients with abnormal acid exposure. PPI medications are safe in short- or long-term use. It is recommended not to maintain cirrhotic patients on PPI therapy without a meaningful indication. Dietary adjustment can provide benefit to some patients, but the data are mixed on how much benefit has been demonstrated from specific food avoidance. Reduction in weight improves reflux. Obesity has measurable effects on the esophageal acid exposure but fewer effects on the motility of the esophagus itself. Controlling weight and changing lifestyle can be helpful for improving GERD symptoms. For some patients in whom either the control of reflux with medications and lifestyle change is not sufficient or a hernia is contributing to symptom generation, surgical and endosurgical interventions can be considered to help manage reflux after a thorough workup with pH testing and manometry.

    View details for DOI 10.1111/nyas.14496

    View details for PubMedID 32944973

  • Marijuana, Ondansetron, and Promethazine Are Perceived as Most Effective Treatments for Gastrointestinal Nausea. Digestive diseases and sciences Zikos, T. A., Nguyen, L., Kamal, A., Fernandez-Becker, N., Regalia, K., Nandwani, M., Sonu, I., Garcia, M., Okafor, P., Neshatian, L., Grewal, D., Garcia, P., Triadafilopoulos, G., Clarke, J. O. 2020


    BACKGROUND: Many anti-nausea treatments are available for chronic gastrointestinal syndromes, but data on efficacy and comparative effectiveness are sparse.AIMS: To conduct a sectional survey study of patients with chronic nausea to assess comparative effectiveness of commonly used anti-nausea treatments.METHODS: Outpatients at a single center presenting for gastroenterology evaluation were asked to rate anti-nausea efficacy on a scale of 0 (no efficacy) to 5 (very effective) of 29 commonly used anti-nausea treatments and provide other information about their symptoms. Additional information was collected from the patients' chart. The primary outcome was to determine which treatments were better or worse than average using a t test. The secondary outcome was to assess differential response by individual patient characteristics using multiple linear regression.RESULTS: One hundred and fifty-three patients completed the survey. The mean efficacy score of all anti-nausea treatments evaluated was 1.73. After adjustment, three treatments had scores statically higher than the mean, including marijuana (2.75, p<0.0001), ondansetron (2.64, p<0.0001), and promethazine (2.46, p<0.0001). Several treatments, including many neuromodulators, complementary and alternative treatments, erythromycin, and diphenhydramine had scores statistically below average. Patients with more severe nausea responded better to marijuana (p=0.036) and diphenhydramine (p<0.001) and less so to metoclopramide (p=0.020). There was otherwise no significant differential response by age, gender, nausea localization, underlying gastrointestinal cause of nausea, and GCSI.CONCLUSIONS: When treating nausea in patients with chronic gastrointestinal syndromes, clinicians may consider trying higher performing treatments first, and forgoing lower performing treatments. Further prospective research is needed, particularly with respect to highly effective treatments.

    View details for DOI 10.1007/s10620-020-06195-5

    View details for PubMedID 32185665

  • Baseline impedance via manometry and ambulatory reflux testing are not equivalent when utilized in the evaluation of potential extra-esophageal gastroesophageal reflux disease. Journal of thoracic disease Zikos, T. A., Triadafilopoulos, G. n., Kamal, A. n., Podboy, A. n., Sonu, I. S., Regalia, K. A., Nandwani, M. C., Nguyen, L. A., Fernandez-Becker, N. Q., Clarke, J. O. 2020; 12 (10): 5628–38


    Esophageal baseline impedance (BI) shows promise for the diagnosis of gastroesophageal reflux disease (GERD), but means of acquisition and relevance to extra-esophageal manifestations of GERD (EE-GERD) remain unclear. In this study we aim to (I) evaluate concordance between BI as measured by 24-hour pH-impedance (pH-MII) and high-resolution impedance manometry (HRIM), and (II) assess relationship to potential EE-GERD symptoms.In this prospective open cohort study, patients presenting for outpatient HRIM and pH-MII studies were prospectively enrolled. All patients completed the GERD-HRQL, NOSE, and respiratory symptom index questionnaire (RSI), plus questions regarding wheezing and dental procedures. HRIM and pH-MII were evaluated with calculation of BI. Correlations were assessed using either Pearson's correlation or Spearman's rank coefficients.70 HRIM patients were enrolled, 35 of whom underwent pH-MII. There was no correlation between BI measurements as assessed by HRIM and pH-MII proximally, but there was moderate-weak correlation distally (r=0.34 to 0.5). Distal acid exposure time correlated with distal BI only for measurements by pH-MII (rho= -0.5 to -0.65), and not by HRIM. There was no relationship between proximal acid exposure time and proximal BI. There were no correlations when comparing proximal or distal BI measurements, acid exposure times, and impedance events to symptoms.Concordance between BI as measured by HRIM and pH-MII is poor, especially proximally, suggesting that these two methods are not interchangeable. There is no correlation between BI both distally/proximally and symptoms of either GERD/EE-GERD, suggesting that many symptoms are unrelated to acid or that BI is not an adequate marker to assess EE-GERD symptoms.

    View details for DOI 10.21037/jtd-20-1623

    View details for PubMedID 33209395

    View details for PubMedCentralID PMC7656325

  • Potential proton pump inhibitor-related adverse effects. Annals of the New York Academy of Sciences Perry, I. E., Sonu, I. n., Scarpignato, C. n., Akiyama, J. n., Hongo, M. n., Vega, K. J. 2020


    Proton pump inhibitors (PPIs) are one of the most common medications taken by patients worldwide. PPIs are used to treat acid-related disorders, including gastroesophageal reflux disease, peptic ulcer disease, Helicobacter pylori infection, and nonsteroidal anti-inflammatory drug/stress ulceration. For some of these diseases, long-term treatment is necessary. With such prolonged use, concern and investigation into potential adverse effects has increased. In addition, data are available regarding potential anticancer effects of PPIs, especially regarding solid tumors. The aim of this review is to assess the literature on PPIs with regard to common concerns, such as drug-drug interactions, the intestinal microbiome, dementia and central nervous system disease, and osteoporosis, as well as to highlight potential negative and positive impacts of the drug in cancer.

    View details for DOI 10.1111/nyas.14428

    View details for PubMedID 32761834

  • The esophageal mucosal barrier in health and disease: mucosal pathophysiology and protective mechanisms. Annals of the New York Academy of Sciences Gyawali, C. P., Sonu, I. n., Becker, L. n., Sarosiek, J. n. 2020


    Diseases of the esophagus, such as gastroesophageal reflux (GER), can result in changes to mucosal integrity, neurological function, and the microbiome. Although poorly understood, both age and GER can lead to changes to the enteric nervous system. In addition, the esophagus has a distinct microbiome that can be altered in GER. Mucosal integrity is also at risk due to persistent damage from acid. Diagnostic tools, such as ambulatory pH/impedance testing and esophageal mucosal impedance, can assess short-term and longitudinal GER burden, which can also assess the risk for mucosal compromise. The quality of the mucosal barrier is determined by its intercellular spaces, tight junctions, and tight junction proteins, which are represented by claudins, occludins, and adhesion molecules. Fortunately, there are protective factors for mucosal integrity that are secreted by the esophageal submucosal mucous glands and within saliva that are augmented by mastication. These protective factors have potential as therapeutic targets for GER. In this article, we aim to review diagnostic tools used to predict mucosal integrity, aging, and microbiome changes to the esophagus and esophageal mucosal defense mechanisms.

    View details for DOI 10.1111/nyas.14521

    View details for PubMedID 33128243

  • Ninety-Six Hour Wireless Esophageal pH Study in Patients with GERD Shows that Restrictive Diet Reduces Esophageal Acid Exposure. Digestive diseases and sciences Triadafilopoulos, G., Korzilius, J. W., Zikos, T., Sonu, I., Fernandez-Becker, N. Q., Nguyen, L., Clarke, J. O. 2019


    BACKGROUND: Prolonged (96h) pH monitoring may explore the effect of diet on pH and symptoms in patients with GERD.AIMS: To assess the usefulness of a 96h esophageal pH study in patients with GER symptoms under different diets (pro- and anti-GER).METHODS: Prospective study of 66 patients with GERD undergoing wireless 96h pH monitoring. Two-day periods, one on liberal (pro-reflux) and another on restricted (anti-reflux) diet assessed esophageal acid exposure and symptoms. The primary end point was normalization of acid exposure time while on restricted diet. Secondary end point was a>50% reduction in symptoms with restricted diet.RESULTS: Normal (pH time<4 of<6%) was found in 34 patients (51.5%) while on the initial 48h (liberal) diet [median % time<4: 3.2 (95% CI, 1.9, 4.0)] and remained normal while on restricted diet [median % time<4: 2.6 (95% CI, 0.8, 3.4)]. Abnormal acid exposure (% pH time<4:>6%) was found in 32 patients (48.5%) while on initial 48h liberal diet [median % time<4: 10.5, (95% CI 8.9, 12.6)], and decreased significantly with restricted diet [median % time<4: 4.5 (95% CI 3.1, 7.3)] (p=0.001), and normalized with anti-GERD diet in 21 patients (65.6%). Only 11/66 patients were candidates for proton pump inhibitor (PPI) use; 34 had either normal pH studies or normalized them with restricted diet (n=21). Symptoms did not improve with restricted diet.CONCLUSIONS: The 96-h esophageal pH study tests for GERD under pro- and anti-GER diets and allows minimization of PPI therapy to only 16.6% of patients.

    View details for DOI 10.1007/s10620-019-05940-9

    View details for PubMedID 31734874

  • Esophagogastroduodenoscopy and Esophageal Involvement in Patients with Pemphigus Vulgaris. Dysphagia Ozeki, K. A., Zikos, T. A., Clarke, J. O., Sonu, I. n. 2019


    Pemphigus vulgaris (PV) is a rare autoimmune blistering disease involving the skin and mucous membranes. The prevalence of esophageal involvement remains uncertain. The aim of our study was to determine the frequency of esophageal involvement in patients with PV. This is a single-center electronic database retrospective review of patients with a diagnosis of PV. Data abstracted included demographics, disease characteristics (biopsy results, symptoms, areas affected, treatments), and esophagogastroduodenoscopy (EGD) reports. Of the 111 patients that met eligibility criteria, only 22 (19.8%) underwent EGD. Demographic data were similar except those who underwent EGD were more likely to be female (77.3% vs. 51.7%, p = 0.05) and have hypertension (50.0% vs. 24.7%, p = 0.04). Esophageal symptoms were common in both groups; however, those experiencing dysphagia were more likely to undergo EGD (50.0% vs. 20.2%, p = 0.007). Those who underwent EGD had more refractory disease (≥ 3 treatment modalities: 100% vs. 58.4%, p < 0.001), but did not differ in areas affected. Of those who underwent EGD, only 4 (18.2%) had esophageal abnormalities either prior to PV diagnosis (1) or during a disease flare (3). Those having a flare were more likely to experience odynophagia (69.2%) or weight loss (61.5%), p = 0.02 and p = 0.05, respectively. While esophageal symptoms were common in our cohort of PV patients, a minority of patients underwent EGD, and the vast majority of those were unremarkable. This suggests that while esophageal symptoms are common in PV, permanent esophageal injury is more rare.

    View details for DOI 10.1007/s00455-019-10055-4

    View details for PubMedID 31538221

  • A Positive Correlation Between Gastric and Esophageal Dysmotility Suggests Common Causality DIGESTIVE DISEASES AND SCIENCES Zikos, T. A., Clarke, J. O., Triadafilopoulos, G., Regalia, K. A., Sonu, I. S., Fernandez-Becker, N. Q., Nandwani, M. C., Nguyen, L. A. 2018; 63 (12): 3417–24
  • Esophagogastroduodenoscopy and Esophageal Involvement in Patients With Pemphigus Vulgaris Ozeki, K., Zikos, T. A., Clarke, J., Sonu, I. NATURE PUBLISHING GROUP. 2018: S177
  • Use of Esophageal pH Monitoring to Minimize Proton-Pump Inhibitor Utilization in Patients with Gastroesophageal Reflux Symptoms DIGESTIVE DISEASES AND SCIENCES Triadafilopoulos, G., Zikos, T., Regalia, K., Sonu, I., Fernandez-Becker, N. Q., Nguyen, L., Nandwani, M. R., Clarke, J. O. 2018; 63 (10): 2673–80
  • Use of Esophageal pH Monitoring to Minimize Proton-Pump Inhibitor Utilization in Patients with Gastroesophageal Reflux Symptoms. Digestive diseases and sciences Triadafilopoulos, G., Zikos, T., Regalia, K., Sonu, I., Fernandez-Becker, N. Q., Nguyen, L., Nandwani, M. C., Clarke, J. O. 2018


    BACKGROUND: Due to concerns about long-term PPI use in patients with acid reflux, we aimed at minimizing PPI use, either by avoiding initiating therapy, downscaling to other therapies, or introducing endoscopic or surgical options.AIMS: To examine the role of esophageal ambulatory pHmetry in minimizing PPI use in patients with heartburn and acid regurgitation.METHODS: Retrospective cohort analysis of patients with reflux symptoms, who underwent endoscopy, manometry, and ambulatory pHmetry to define the need for PPI. Patients were classified as: (1) never users; (2) partial responders to PPI; (3) users with complete response to PPI. Patients were then managed as: (1) PPI non-users; (2) PPI-initiated, and (3) PPI-continued.RESULTS: Of 286 patients with heartburn and regurgitation, 103 (36%) were found to have normal and 183 (64%) abnormal esophageal acid exposure (AET). In the normal AET group, 44/103 had not been treated and were not initiated on PPI. Of the 59 who had previously received PPI, 52 stopped and 7 continued PPI. Hence, PPI were avoided in 96/103 patients (93%). In the abnormal AET group, 61/183 had not been treated and 38 were initiated on PPI and 23 on other therapies. In the 122 patients previously treated with PPI, 24 were not treated with PPI, but with H2RAs, prokinetics, endoscopic, or surgical therapy. Hence, PPI therapy was avoided in 47/183 patients (26%).CONCLUSIONS: In patients with GER symptoms, esophageal pHmetry may avert PPI use in 50%. In the era of caution regarding PPIs, early testing may provide assurance and justification.

    View details for PubMedID 29959725

  • A Positive Correlation Between Gastric and Esophageal Dysmotility Suggests Common Causality. Digestive diseases and sciences Zikos, T. A., Clarke, J. O., Triadafilopoulos, G., Regalia, K. A., Sonu, I. S., Fernandez-Becker, N. Q., Nandwani, M. C., Nguyen, L. A. 2018


    BACKGROUND: Gastric and esophageal dysmotility syndromes are some of the most common motility diagnoses, but little is known about their interrelationship.AIMS: The aim of our study was to determine if a correlation exists between gastric and esophageal dysmotility syndromes.METHODS: We reviewed the records of all patients who underwent both solid gastric emptying scintigraphy (GES) and high-resolution esophageal manometry (HRM) withina 2 year period, with both done between August 2012 and August 2017. All GESs were classified as either rapid, normal, or delayed. All HRMs were classified according to the Chicago Classification 3.0. Correlations were assessed using Fisher's exact test and multiple logistic regression.RESULTS: In total, 482 patients met inclusion criteria. Of patients with a normal, delayed, and rapid GES, 53.1, 64.5, and 77.3% had an abnormal HRM, respectively (p<0.05 vs. normal GES). Likewise, patients with an abnormal HRM were more likely to have an abnormal GES (54.9 vs. 41.8%, p=0.005). Multiple logistic regression showed abnormal GES [odds ratio (OR) 2.14], age (OR 1.013), scleroderma (OR 6.29), and dysphagia (OR 2.63) were independent predictors of an abnormal HRM. Likewise, an abnormal HRM (OR 2.11), diabetes (OR 1.85), heart or lung transplantation (OR 2.61), and autonomic dysfunction (OR 2.37) were independent predictors of an abnormal GES.CONCLUSIONS: The correlation between an abnormal GES and HRM argues for common pathogenic mechanisms of these motility disorders, and possibly common future treatment options. Clinicians should have a high index of suspicion for another motility disorder if one is present.

    View details for PubMedID 29946871

  • Persistent constipation and abdominal adverse events with newer treatments for constipation. BMJ open gastroenterology Sonu, I., Triadafilopoulos, G., Gardner, J. D. 2016; 3 (1)


    Clinical trials of several new treatments for opioid-induced constipation (OIC), chronic idiopathic constipation (CIC) and constipation-predominant irritable bowel syndrome (IBS-C) have focused on differences between subjects relieved of constipation with placebo and active treatment. Patients and clinicians however, are more interested in the probability these treatments provide actual relief of constipation and its associated symptoms.We searched the medical literature using MEDLINE and Cochrane central register of controlled trials. Randomised, placebo-controlled trials that examined the use of methylnaltrexone, naloxegol, lubiprostone, prucalopride or linaclotide in adults with OIC, CIC and IBS-C were eligible for inclusion. The primary efficacy measure was relief of constipation. Adverse event data for abdominal symptoms were also analysed.25 publications were included in our analyses. The proportion of constipated individuals with active treatment was significantly lower than the proportion with placebo; however, in 15 of these 20 trials analysed, a majority of patients remained constipated with active treatment. Analyses of adverse event data revealed that the percentage of participants who experienced abdominal pain, diarrhoea and flatulence with active treatment was higher than that with placebo in the majority of trials analysed.Newer pharmacological treatments for constipation are superior to placebo in relieving constipation, but many patients receiving active treatment may remain constipated. In addition, all 5 of the treatments studied are accompanied by no change or a possible increase in the prevalence of abdominal symptoms, such as abdominal pain, diarrhoea and flatulence.

    View details for DOI 10.1136/bmjgast-2016-000094

    View details for PubMedID 27486521

    View details for PubMedCentralID PMC4947709

  • Vitamin Abnormalities in Patients With Gastrointestinal Motility and Functional Disorders Sonu, I., Wang, L., Zia, J., Nguyen, L. NATURE PUBLISHING GROUP. 2015: S751
  • 5-ASA Induced Recurrent Myopericarditis and Cardiac Tamponade in a Patient with Ulcerative Colitis DIGESTIVE DISEASES AND SCIENCES Sonu, I., Wong, R., Rothenberg, M. E. 2013; 58 (8): 2148-2150

    View details for DOI 10.1007/s10620-013-2566-4

    View details for Web of Science ID 000322650900007

    View details for PubMedID 23361575

  • Papillary thyroid cancer and inflammatory bowel disease: Is there a relationship? WORLD JOURNAL OF GASTROENTEROLOGY Sonu, I. S., Blonski, W., Lin, M. V., Lewis, J., Aberra, F., Lichtenstein, G. R. 2013; 19 (7): 1079-1084


    To formally study age of diagnosis of papillary thyroid cancer (PTC) in inflammatory bowel disease (IBD) patients and evaluate the prevalence of PTC in IBD patients compared to a control population.We were interested in testing the hypothesis that patients with IBD are more likely to be diagnosed with PTC than a control population. A retrospective cohort analysis was performed using the University of Pennsylvania Health System's electronic database. Outpatients from 1998-2009 were included in the search, and patients in the cohort were selected based on ICD-9 codes. Inclusion criteria included the diagnosis of Crohn's disease (CD) or ulcerative colitis (UC) and the concurrent diagnosis of thyroid cancer in comparison to a control population. Using these methods 912 patients with CD and 1774 with UC were compared to 1638 diverticulitis and 19 447 asthma controls. Statistics were performed using corrected chi-square analysis. The primary outcome for this study was the diagnosis of PTC. Approval to conduct this study was obtained by the Institutional Review Board at the University of Pennsylvania.The mean age was 47.5 years (range: 18-102 years) and 66% patients were female. An analysis of variance model was used to compare the age of PTC diagnosis between the CD, UC, asthma and diverticulitis groups, and a statistically significant difference in age at PTC diagnosis was noted across all groups (F = 6.35, df = 3, P = 0.0006). The age of PTC diagnosis in CD patients was statistically significantly lower than UC, asthma, and diverticulitis patients (average PTC diagnosis age for CD 25, UC 49, asthma 45, diverticulitis 63). After covarying for sex and age in 2009, the difference in age at PTC diagnosis remained statistically significant (F = 4.13, df = 3, P = 0.0089). A total of 86 patients were diagnosed with PTC. Nine patients (0.5%) with UC were diagnosed with PTC. Patients with UC were not shown to be more likely to develop PTC [odds ratio (OR): 1.544, 95%CI 0.767-3.108] compared to asthma controls. Four patients (0.4%) with CD were diagnosed with PTC. Patients with CD were not shown to be more likely to develop PTC (OR: 1.334, 95%CI 0.485-3.672) compared to a control population with asthma. Nine patients (0.5%) with a history of diverticulitis were diagnosed with PTC. Patients with diverticulitis were not shown to be more likely to develop PTC (OR: 1.673, 95%CI 0.831-3.368) compared to asthma controls. Patients with CD or UC were not less likely to develop PTC compared to those with diverticulitis (CD OR: 0.80, 95%CI 0.25-2.60; UC OR: 0.92, 95%CI 0.37-2.33). None of the patients used immunosuppressant medications prior to the diagnosis of PTC (azathioprine, 6-mercaptopurine, and methotrexate).There is a significant difference in age of diagnosis of PTC in patients with CD compared to patients with UC and the control populations studied.

    View details for DOI 10.3748/wjg.v19.i7.1079

    View details for Web of Science ID 000315203400013

    View details for PubMedID 23467027

    View details for PubMedCentralID PMC3581995

  • Higher rates of hepatitis B surface antigen (HBsAg) seroclearance in males and in hepatitis B e-antigen negative chronic hepatitis B (CHB) among treatment naive patients in a large multicenter US cohort study 63rd Annual Meeting of the American-Association-for-the-Study-of-Liver-Diseases (AASLD) Nguyen, L. H., Sonu, I. S., Kin, K. C., Trinh, H. N., Li, J., Zhang, J. Q., Ahmed, A., Nguyen, M. H. WILEY-BLACKWELL. 2012: 352A–352A
  • Incidence and Risk Factors in the Development of Hepatocellular Carcinoma (HCC) in Non-Cirrhotic and Cirrhotic Patients with Chronic Hepatitis B (CHB): Results of a Multicenter US Cohort Study 63rd Annual Meeting of the American-Association-for-the-Study-of-Liver-Diseases (AASLD) Sonu, I. S., Nguyen, L. H., Chen, C., Kin, K. C., Ha, N. B., Trinh, H. N., Ahmed, A., Li, J., Zhang, J. Q., Nguyen, M. H. WILEY-BLACKWELL. 2012: 478A–479A
  • Clinical Pharmacology of 5-ASA Compounds in Inflammatory Bowel Disease GASTROENTEROLOGY CLINICS OF NORTH AMERICA Sonu, I., Lin, M. V., Blonski, W., Lichtenstein, G. R. 2010; 39 (3): 559-?


    Mesalamine has been the first-line of therapy in patients with inflammatory bowel disease (IBD) since the 1960s. This article serves as a review of the different 5-aminosalicylic acid compounds, release formulations, use and dosing in the treatment of IBD, in particular ulcerative colitis.

    View details for DOI 10.1016/j.gtc.2010.08.011

    View details for Web of Science ID 000284291900011

    View details for PubMedID 20951918

  • An approach to the management of refractory ulcerative colitis. Minerva gastroenterologica e dietologica Sonu, I., Blonski, W., Lin, M. V., Lichtenstein, G. R. 2010; 56 (2): 213-231


    Ulcerative colitis (UC) is a chronic inflammatory bowel disease of unknown etiology associated with dysregulation of the gastrointestinal mucosal immune system. It is characterized by a waxing and waning course and approximately 15% of UC patients will experience a severe episode. The first line treatment for severe colitis includes IV corticosteroids, however, 40% of patients are non-responsive to corticosteroid therapy and may require either colectomy, intravenous infliximab or intravenous cyclosporine within 3-5 days of presentation. This review focuses on the management and treatment approaches to refractory UC.

    View details for PubMedID 20485258

  • An evaluation of geriatrics activities within internal medicine subspecialties AMERICAN JOURNAL OF MEDICINE Sonu, I. S., High, K. P., Clayton, C. P., Woolard, N. F., Hazzard, W. R. 2006; 119 (11): 995-1000

    View details for DOI 10.1016/j.amjmed.2006.07.038

    View details for Web of Science ID 000241629000025

    View details for PubMedID 17071172