Education & Certifications

  • MS, Harvard University, Biostatistics
  • BS, Carnegie Mellon University, Business Administration

All Publications

  • Cost Effectiveness of Subsidizing Fruit and Vegetable Purchases Through the Supplemental Nutrition Assistance Program. American journal of preventive medicine Choi, S. E., Seligman, H., Basu, S. 2017


    A diet high in fruits and vegetables (FV) is associated with reduced risk of chronic disease. One strategy to incentivize FV consumption among low-income households is to make them more affordable through the Supplemental Nutrition Assistance Program (SNAP). This study aims to identify the cost effectiveness of subsidizing FV purchases among the one in seven Americans who participate in SNAP.A cost-effectiveness analysis was conducted from a societal perspective to estimate lifetime costs and health gains associated with subsidizing FV purchases. A stochastic microsimulation model of obesity, type 2 diabetes, myocardial infarction, and stroke in the 2015 U.S. population was used. Model parameters were based on nationally representative SNAP participation and dietary consumption data from the National Health and Nutrition Examination Survey (2003-2012), and data from a randomized trial of FV subsidies among SNAP users.Despite cycling of participants in and out of SNAP, expanding an FV subsidy nationwide through SNAP would be expected to reduce incidence of type 2 diabetes by 1.7% (95% CI=1.2, 2.2), myocardial infarction by 1.4% (95% CI=0.9, 1.9), stroke by 1.2% (95% CI=0.8, 1.6), and obesity by 0.2% (95% CI=0.1, 0.3), and be cost saving from a societal perspective. The saved costs would be largely attributable to long-term reductions in type 2 diabetes and cardiovascular diseases.The model suggests nationwide SNAP FV subsidies would reduce chronic disease morbidity, mortality, and costs over long time horizons that are unlikely to be observed in short-term community-based trials.

    View details for DOI 10.1016/j.amepre.2016.12.013

    View details for PubMedID 28153648

    View details for PubMedCentralID PMC5401647

  • Cost-effectiveness of malaria preventive treatment for HIV-infected pregnant women in sub-Saharan Africa. Malaria journal Choi, S. E., Brandeau, M. L., Bendavid, E. 2017; 16 (1): 403


    Malaria is a leading cause of morbidity and mortality among HIV-infected pregnant women in sub-Saharan Africa: at least 1 million pregnancies among HIV-infected women are complicated by co-infection with malaria annually, leading to increased risk of premature delivery, severe anaemia, delivery of low birth weight infants, and maternal death. Current guidelines recommend either daily cotrimoxazole (CTX) or intermittent preventive treatment with sulfadoxine-pyrimethamine (IPTp-SP) for HIV-infected pregnant women to prevent malaria and its complications. The cost-effectiveness of CTX compared to IPTp-SP among HIV-infected pregnant women was assessed.A microsimulation model of malaria and HIV among pregnant women in five malaria-endemic countries in sub-Saharan Africa was constructed. Four strategies were compared: (1) 2-dose IPTp-SP at current IPTp-SP coverage of the country ("2-IPT Low"); (2) 3-dose IPTp-SP at current coverage ("3-IPT Low"); (3) 3-dose IPTp-SP at the same coverage as antiretroviral therapy (ART) in the country ("3-IPT High"); and (4) daily CTX at ART coverage. Outcomes measured include maternal malaria, anaemia, low birth weight (LBW), and disability-adjusted life years (DALYs). Sensitivity analyses assessed the effect of adherence to CTX.Compared with the 2-IPT Low Strategy, women receiving CTX had 22.5% fewer LBW infants (95% CI 22.3-22.7), 13.5% fewer anaemia cases (95% CI 13.4-13.5), and 13.6% fewer maternal malaria cases (95% CI 13.6-13.7). In all simulated countries, CTX was the preferred strategy, with incremental cost-effectiveness ratios ranging from cost-saving to $3.9 per DALY averted from a societal perspective. CTX was less effective than the 3-IPT High Strategy when more than 18% of women stopped taking CTX during the pregnancy.In malarious regions of sub-Saharan Africa, daily CTX for HIV-infected pregnant women regardless of CD4 cell count is cost-effective compared with 3-dose IPTp-SP as long as more than 82% of women adhere to daily dosing.

    View details for DOI 10.1186/s12936-017-2047-x

    View details for PubMedID 28985732

  • Dynamic treatment selection and modification for personalised blood pressure therapy using a Markov decision process model: a cost-effectiveness analysis. BMJ open Choi, S. E., Brandeau, M. L., Basu, S. 2017; 7 (11): e018374


    Personalised medicine seeks to select and modify treatments based on individual patient characteristics and preferences. We sought to develop an automated strategy to select and modify blood pressure treatments, incorporating the likelihood that patients with different characteristics would benefit from different types of medications and dosages and the potential severity and impact of different side effects among patients with different characteristics.We developed a Markov decision process (MDP) model to incorporate meta-analytic data and estimate the optimal treatment for maximising discounted lifetime quality-adjusted life-years (QALYs) based on individual patient characteristics, incorporating medication adjustment choices when a patient incurs side effects. We compared the MDP to current US blood pressure treatment guidelines (the Eighth Joint National Committee, JNC8) and a variant of current guidelines that incorporates results of a major recent trial of intensive treatment (Intensive JNC8). We used a microsimulation model of patient demographics, cardiovascular disease risk factors and side effect probabilities, sampling from the National Health and Nutrition Examination Survey (2003-2014), to compare the expected population outcomes from adopting the MDP versus guideline-based strategies.Costs and QALYs for the MDP-based treatment (MDPT), JNC8 and Intensive JNC8 strategies.Compared with the JNC8 guideline, the MDPT strategy would be cost-saving from a societal perspective with discounted savings of US$1187 per capita (95% CI 1178 to 1209) and an estimated discounted gain of 0.06 QALYs per capita (95% CI 0.04 to 0.08) among the US adult population. QALY gains would largely accrue from reductions in severe side effects associated with higher treatment doses later in life. The Intensive JNC8 strategy was dominated by the MDPT strategy.An MDP-based approach can aid decision-making by incorporating meta-analytic evidence to personalise blood pressure treatment and improve overall population health compared with current blood pressure treatment guidelines.

    View details for DOI 10.1136/bmjopen-2017-018374

    View details for PubMedID 29146652

    View details for PubMedCentralID PMC5695480

  • Expansion of the National Salt Reduction Initiative: A Mathematical Model of Benefits and Risks of Population-Level Sodium Reduction MEDICAL DECISION MAKING Choi, S. E., Brandeau, M. L., Basu, S. 2016; 36 (1): 72-85


    . The National Salt Reduction Initiative, in which food producers agree to lower sodium to levels deemed feasible for different foods, is expected to significantly reduce sodium intake if expanded to a large sector of food manufacturers.. Given recent data on the relationship between sodium intake, hypertension, and associated cardiovascular disease at a population level, we sought to examine risks and benefits of the program.. To estimate the impact of further expanding the initiative on hypertension, myocardial infarction (MI) and stroke incidence, and related mortality, given food consumption patterns across the United States, we developed and validated a stochastic microsimulation model of hypertension, MI, and stroke morbidity and mortality, using data from food producers on sodium reduction among foods, linked to 24-hour dietary recalls, blood pressure, and cardiovascular histories from the National Health and Nutrition Examination Survey.. Expansion of the initiative to ensure all restaurants and manufacturers reach agreed-upon sodium targets would be expected to avert from 0.9 to 3.0 MIs (a 1.6%-5.4% reduction) and 0.5 to 2.8 strokes (a 1.1%-6.2% reduction) per 10,000 Americans per year over the next decade, after incorporating consumption patterns and variations in the effect of sodium reduction on blood pressure among different demographic groups. Even high levels of consumer addition of table salt or substitution among food categories would be unlikely to neutralize this benefit. However, if recent epidemiological associations between very low sodium and increased mortality are causal, then older women may be at risk of increased mortality from excessively low sodium intake.An expanded National Salt Reduction Initiative is likely to significantly reduce hypertension and hypertension-related cardiovascular morbidity but may be accompanied by potential risks to older women.

    View details for DOI 10.1177/0272989X15583846

    View details for Web of Science ID 000366910300008

    View details for PubMedID 25926284

  • Personalizing Annual Lung Cancer Screening for Patients With Chronic Obstructive Pulmonary Disease: A Decision Analysis CANCER Lowry, K. P., Gazelle, G. S., Gilmore, M. E., Johanson, C., Munshi, V., Choi, S. E., Tramontano, A. C., Kong, C. Y., McMahon, P. M. 2015; 121 (10): 1556-1562


    Lung cancer screening with annual chest computed tomography (CT) is recommended for current and former smokers with a ≥30-pack-year smoking history. Patients with chronic obstructive pulmonary disease (COPD) are at increased risk of developing lung cancer and may benefit from screening at lower pack-year thresholds.We used a previously validated simulation model to compare the health benefits of lung cancer screening in current and former smokers ages 55-80 with ≥30 pack-years with hypothetical programs using lower pack-year thresholds for individuals with COPD (≥20, ≥10, and ≥1 pack-years). Calibration targets for COPD prevalence and associated lung cancer risk were derived using the Framingham Offspring Study limited data set. We performed sensitivity analyses to evaluate the stability of results across different rates of adherence to screening, increased competing mortality risk from COPD, and increased surgical ineligibility in individuals with COPD. The primary outcome was projected life expectancy.Programs using lower pack-year thresholds for individuals with COPD yielded the highest life expectancy gains for a given number of screens. Highest life expectancy was achieved when lowering the pack-year threshold to ≥1 pack-year for individuals with COPD, which dominated all other screening strategies. These results were stable across different adherence rates to screening and increases in competing mortality risk for COPD and surgical ineligibility.Current and former smokers with COPD may disproportionately benefit from lung cancer screening. A lower pack-year threshold for screening eligibility may benefit this high-risk patient population.

    View details for DOI 10.1002/cncr.29225

    View details for Web of Science ID 000354216800008

    View details for PubMedID 25652107

    View details for PubMedCentralID PMC4492436

  • High-resolution microendoscopy for esophageal cancer screening in China: A cost-effectiveness analysis WORLD JOURNAL OF GASTROENTEROLOGY Hur, C., Choi, S. E., Kong, C. Y., Wang, G., Xu, H., Polydorides, A. D., Xue, L., Perzan, K. E., Tramontano, A. C., Richards-Kortum, R. R., Anandasabapathy, S. 2015; 21 (18): 5513-5523


    To study the cost-effectiveness of high-resolution microendoscopy (HRME) in an esophageal squamous cell carcinoma (ESCC) screening program in China.A decision analytic Markov model of ESCC was developed. Separate model analyses were conducted for cohorts consisting of an average-risk population or a high-risk population in China. Hypothetical 50-year-old individuals were followed until age 80 or death. We compared three different strategies for both cohorts: (1) no screening; (2) standard endoscopic screening with Lugol's iodine staining; and (3) endoscopic screening with Lugol's iodine staining and an HRME. Model parameters were estimated from the literature as well as from GLOBOCAN, the Cancer Incidence and Mortality Worldwide cancer database. Health states in the model included non-neoplasia, mild dysplasia, moderate dysplasia, high-grade dysplasia, intramucosal carcinoma, operable cancer, inoperable cancer, and death. Separate ESCC incidence transition rates were generated for the average-risk and high-risk populations. Costs in Chinese currency were converted to international dollars (I$) and were adjusted to 2012 dollars using the Consumer Price Index.The main outcome measurements for this study were quality-adjusted life years (QALYs) and incremental cost-effectiveness ratio (ICER). For the average-risk population, the HRME screening strategy produced 0.043 more QALYs than the no screening strategy at an additional cost of I$646, resulting in an ICER of I$11808 per QALY gained. Standard endoscopic screening was weakly dominated. Among the high-risk population, when the HRME screening strategy was compared with the standard screening strategy, the ICER was I$8173 per QALY. For both the high-risk and average-risk screening populations, the HRME screening strategy appeared to be the most cost-effective strategy, producing ICERs below the willingness-to-pay threshold, I$23500 per QALY. One-way sensitivity analysis showed that, for the average-risk population, higher specificity of Lugol's iodine (> 40%) and lower specificity of HRME (< 70%) could make Lugol's iodine screening cost-effective. For the high-risk population, the results of the model were not substantially affected by varying the follow-up rate after Lugol's iodine screening, Lugol's iodine test characteristics (sensitivity and specificity), or HRME specificity.The incorporation of HRME into an ESCC screening program could be cost-effective in China. Larger studies of HRME performance are needed to confirm these findings.

    View details for DOI 10.3748/wjg.v21.i18.5513

    View details for Web of Science ID 000354800200009

    View details for PubMedID 25987774

    View details for PubMedCentralID PMC4427673

  • Comparing Benefits from Many Possible Computed Tomography Lung Cancer Screening Programs: Extrapolating from the National Lung Screening Trial Using Comparative Modeling PLOS ONE McMahon, P. M., Meza, R., Plevritis, S. K., Black, W. C., Tammemagi, C. M., Erdogan, A., ten Haaf, K., Hazelton, W., Holford, T. R., Jeon, J., Clarke, L., Kong, C. Y., Choi, S. E., Munshi, V. N., Han, S. S., van Rosmalen, J., Pinsky, P. F., Moolgavkar, S., de Koning, H. J., Feuer, E. J. 2014; 9 (6)
  • Comparative Analysis of 5 Lung Cancer Natural History and Screening Models That Reproduce Outcomes of the NLST and PLCO Trials CANCER Meza, R., ten Haaf, K., Kong, C. Y., Erdogan, A., Black, W. C., Tammemagi, M. C., Choi, S. E., Jeon, J., Han, S. S., Munshi, V., van Rosmalen, J., Pinsky, P., McMahon, P. M., de Koning, H. J., Feuer, E. J., Hazelton, W. D., Plevritis, S. K. 2014; 120 (11): 1713-1724

    View details for DOI 10.1002/cncr.28623

    View details for Web of Science ID 000336619700021

  • Benefits and Harms of Computed Tomography Lung Cancer Screening Strategies: A Comparative Modeling Study for the US Preventive Services Task Force ANNALS OF INTERNAL MEDICINE de Koning, H. J., Meza, R., Plevritis, S. K., ten Haaf, K., Munshi, V. N., Jeon, J., Erdogan, S. A., Kong, C. Y., Han, S. S., van Rosmalen, J., Choi, S. E., Pinsky, P. F., de Gonzalez, A. B., Berg, C. D., Black, W. C., Tammemaegi, M. C., Hazelton, W. D., Feuer, E. J., McMahon, P. M. 2014; 160 (5): 311-?
  • Statins and aspirin for chemoprevention in Barrett's esophagus: results of a cost-effectiveness analysis. Cancer prevention research Choi, S. E., Perzan, K. E., Tramontano, A. C., Kong, C. Y., Hur, C. 2014; 7 (3): 341-350


    Data suggest that aspirin, statins, or a combination of the two drugs may lower the progression of Barrett's esophagus to esophageal adenocarcinoma. However, aspirin is associated with potential complications such as gastrointestinal bleeding and hemorrhagic stroke, and statins are associated with myopathy. We developed a simulation disease model to study the effectiveness and cost effectiveness of aspirin and statin chemoprevention against esophageal adenocarcinoma. A decision analytic Markov model was constructed to compare four strategies for Barrett's esophagus management; all regimens included standard endoscopic surveillance regimens: (i) endoscopic surveillance alone, (ii) aspirin therapy, (iii) statin therapy, and (iv) combination therapy of aspirin and statin. Endpoints evaluated were life expectancy, quality-adjusted life years (QALY), costs, and incremental cost-effectiveness ratios (ICER). Sensitivity analysis was performed to determine the impact of model input uncertainty on results. Assuming an annual progression rate of 0.33% per year from Barrett's esophagus to esophageal adenocarcinoma, aspirin therapy was more effective and cost less than (dominated) endoscopic surveillance alone. When combination therapy was compared with aspirin therapy, the ICER was $158,000/QALY, which was above our willingness-to-pay threshold of $100,000/QALY. Statin therapy was dominated by combination therapy. When higher annual cancer progression rates were assumed in the model (0.5% per year), combination therapy was cost-effective compared with aspirin therapy, producing an ICER of $96,000/QALY. In conclusion, aspirin chemoprevention was both more effective and cost less than endoscopic surveillance alone. Combination therapy using both aspirin and statin is expensive but could be cost-effective in patients at higher risk of progression to esophageal adenocarcinoma.

    View details for DOI 10.1158/1940-6207.CAPR-13-0191-T

    View details for PubMedID 24380852

  • Exploring the Recent Trend in Esophageal Adenocarcinoma Incidence and Mortality Using Comparative Simulation Modeling. Cancer epidemiology, biomarkers & prevention : a publication of the American Association for Cancer Research, cosponsored by the American Society of Preventive Oncology 2014


    Background: The incidence of esophageal adenocarcinoma (EAC) has increased five-fold in the United States since 1975. The aim of our study was to estimate future U.S. EAC incidence and mortality and to shed light on the potential drivers in the disease process that are conduits for the dramatic increase in EAC incidence. Methods: A consortium of three research groups calibrated independent mathematical models to clinical and epidemiologic data including EAC incidence from the Surveillance, Epidemiology, and End Results (SEER 9) registry from 1975-2010. We then used a comparative modeling approach to project EAC incidence and mortality to year 2030. Results: Importantly, all three models identified birth cohort trends affecting cancer progression as a major driver of the observed increases in EAC incidence and mortality. All models predict that incidence and mortality rates will continue to increase until 2030 but with a plateauing trend for recent male cohorts. The predicted ranges of incidence and mortality rates (cases per 100,000 person years) in 2030 are 8.4-10.1 and 5.4-7.4 respectively for males, and 1.3-1.8 and 0.9-1.2 for females. Estimates of cumulative cause-specific EAC deaths among both sexes for years 2011-2030 range between 142,300 and 186,298, almost double the number of deaths in the past 20 years. Conclusions: Through comparative modeling, the projected increases in EAC cases and deaths represent a critical public health concern that warrants attention from cancer control planners to prepare potential interventions. Impact: Quantifying this burden of disease will aid health policy makers to plan appropriate cancer control measures.

    View details for DOI 10.1158/1055-9965.EPI-13-1233

    View details for PubMedID 24692500

  • Incidence and Predictors of Adenocarcinoma Following Endoscopic Ablation of Barrett's Esophagus. Digestive diseases and sciences 2014


    The rate and risk factors of recurrent or metachronous adenocarcinoma following endoscopic ablation therapy in patients with Barrett's esophagus (BE) have not been specifically reported.The aim of this study was to determine the incidence and predictors of adenocarcinoma after ablation therapy for BE high-grade dysplasia (HGD) or intramucosal carcinoma (IMC).This is a single center, retrospective review of prospectively collected data on consecutive cases of endoscopic ablation for BE. A total of 223 patients with BE (HGD or IMC) were treated by ablation between 1996 and 2011. Primary outcome measures were recurrence and new development of adenocarcinoma after ablation. Recurrence was defined as the presence of adenocarcinoma following the absence of adenocarcinoma in biopsy samples from two consecutive surveillance endoscopies. Logistic regression analysis was performed to assess predictors of adenocarcinoma after ablation.One hundred and eighty-three patients were included in the final analysis, and 40 patients were excluded: 22 for palliative ablation, eight lost to follow-up, five for residual carcinoma and five for postoperative state. Median follow-up was 39 months. Recurrence or new development of adenocarcinoma was found in 20 patients (11 %) and the median time to recurrence/development of adenocarcinoma was 11.5 months. Independent predictors of recurrent or metachronous adenocarcinoma were hiatal hernia size ≥ 4 cm (odds ratio 3.649, P = 0.0233) and histology (HGD/adenocarcinoma) after first ablation (odds ratio 4.141, P = 0.0065).Adenocarcinoma after endoscopic therapy for HGD or IMC in BE is associated with large hiatal hernia and histology status after initial ablation therapy.

    View details for DOI 10.1007/s10620-013-3002-5

    View details for PubMedID 24395382

  • The Cost Effectiveness of Radiofrequency Ablation for Barrett's Esophagus GASTROENTEROLOGY Hur, C., Choi, S. E., Rubenstein, J. H., Kong, C. Y., Nishioka, N. S., Provenzale, D. T., Inadomi, J. M. 2012; 143 (3): 567-575


    Radiofrequency ablation (RFA) reduces the risk of esophageal adenocarcinoma (EAC) in patients with Barrett's esophagus (BE) with high-grade dysplasia (HGD), but its effects in patients without dysplasia are debatable. We analyzed the effectiveness and cost effectiveness of RFA for the management of BE.We constructed a decision analytic Markov model. We conducted separate analyses of hypothetical cohorts of patients with BE with dysplasia (HGD or low-grade [LGD]) and without dysplasia. In the analysis of the group with HGD, we compared results of initial RFA with endoscopic surveillance with surgery when cancer was detected. In analyzing the group with LGD or no dysplasia, we compared 3 strategies: endoscopic surveillance with surgery when cancer was detected (S1), endoscopic surveillance with RFA when HGD was detected (S2), and initial RFA followed by endoscopic surveillance (S3).Among patients with HGD, initial RFA was more effective and less costly than endoscopic surveillance. Among patients with LGD, when S3 was compared with S2, the incremental cost-effectiveness ratio was $18,231/quality-adjusted life-year, assuming an annual rate of progression rate from LGD to EAC of 0.5%/year. For patients without dysplasia, S2 was more effective and less costly than S1. In a comparison of S3 with S2, the incremental cost-effectiveness ratios were $205,500, $124,796, and $118,338/quality-adjusted life-year using annual rates of progression of no dysplasia to EAC of 0.12%, 0.33%, or 0.5% per year, respectively.By using updated data, initial RFA might not be cost effective for patients with BE without dysplasia, within the range of plausible rates of progression of BE to EAC, and be prohibitively expensive, from a policy perspective. RFA might be cost effective for confirmed and stable LGD. Initial RFA is more effective and less costly than endoscopic surveillance in HGD.

    View details for DOI 10.1053/j.gastro.2012.05.010

    View details for Web of Science ID 000312158700004

    View details for PubMedID 22626608

  • Screening and surveillance for Barrett's esophagus: current issues and future directions CURRENT OPINION IN GASTROENTEROLOGY Choi, S. E., Hur, C. 2012; 28 (4): 377-381


    Our article discusses the current understanding of screening and surveillance options for Barrett's esophagus and emerging concepts that have the potential to improve the effectiveness and cost-effectiveness of surveillance.Although endoscopic surveillance of patients with Barrett's esophagus is commonly practiced in order to detect high-grade dysplasia and early esophageal adenocarcinoma (EAC), the reported incidence of EAC in Barrett's esophagus patients varies widely. Recent studies found the risk of progression from Barrett's esophagus to EAC to be significantly lower than previously reported, raising concerns regarding the limitations of current surveillance strategies. Advances in imaging techniques and their enhanced diagnostic accuracy may improve the value of endoscopic surveillance. Additionally, various efforts are ongoing to identify biomarkers that identify individuals at higher risk of cancer, possibly allowing for individual risk stratification.These new data highlight some of the opportunities to revise and improve surveillance in patients with Barrett's esophagus. The incorporation of new advances such as imaging techniques and biomarkers has the potential to improve the effectiveness and cost-effectiveness of new surveillance regimens.

    View details for DOI 10.1097/MOG.0b013e328353d58e

    View details for Web of Science ID 000305329800013

    View details for PubMedID 22508325