More than 10 million U.S. adults, including 165,000 veterans who use Veterans Affairs (VA) medical facilities, have class III obesity [body mass index (BMI) 40 kg/m2]. The impact of this epidemic is substantial; in 2000, class III obesity was associated with 82,066 deaths and over $11 billion in direct U.S. health care expenditures. Over the past decade, VHA has provided bariatric surgery to over 1000 severely obese veterans in 12 approved VHA Medical Centers in the hopes of improving their body weight, health, longevity, and potentially also reducing their health care expenditures. The proposed study builds on our prior work by addressing several novel research questions after bariatric surgery was integrated into the MOVE! program.
The purpose of the study was to compare the weight change and resolution of diabetes, hypertension, and hyperlipidemia (Aim 1), long-term survival and surgical complications (Aim 2), long-term trends in VA health care utilization and VA expenditures (Aim 3) of morbidly obese veterans who had bariatric surgery in VA medical centers from 2000 to 2011 with those of a cohort of morbidly obese veterans who did not have surgery. We also proposed a secondary aim to identify the patient factors that moderate the impact of bariatric surgery on the clinical and economic outcomes.
Using numerous VA administrative claims data collected between FY99 and FY13, we constructed survival, weight change, and expenditure outcomes for veterans who had bariatric surgery in VA and veterans who did not have surgery. We identified 2500 surgical cases from the VA Surgical Quality Improvement Program (VASQIP) database and our own independent search of VA inpatient records. These surgical patients were matched to 7,452 non-surgical control patients. Survival was identified from the mini-Vitals dataset, weight was identified from Corporate Data Warehouse data, and VA health expenditures were identified from Managerial Cost Accounting (formerly Decision Support System) Datasets, and patient covariates were obtained from several other VA datasets. We controlled for comorbidity burden via the Diagnostic Cost Group risk adjuster. Survival of the surgical cases was estimated using a Cox proportional survival model, weight change was estimated using mixed effects models, and VA expenditures were estimated using marginalized one-part or two-part models.
In a study published in JAMA that addressed Aim 2, there were a total of 263 deaths among the 2,500 veterans who had bariatric surgery in 2000-2011 and 1,277 deaths among the 7,462 matched control patients at the end of the 14-year study period. Kaplan-Meier estimated one-year, five-year and 10-year mortality rates were 2.4%, 6.4% and 13.8% for surgical patients and 1.7%, 10.4% and 23.9% for controls. Adjusted analysis showed no significant association between bariatric surgery and all-cause mortality in the first year of follow-up [adjusted hazard ratio (HR)=1.28; 95% CI, 0.98-1.68], but significantly lower mortality after one to five years (HR=0.45, 95% CI 0.36-0.56) and five or more years (HR=0.47, 95% CI 0.39-0.58). The mid- (1-to-5 year) and long-term (>5 year) relationships between surgery and survival were not significantly different across groups defined by diabetes diagnosis, sex, and time period of surgery, which addressed our secondary aim.
This study provides the most complete assessment of veterans who have undergone bariatric surgery from 2000 to 2011, which provides a rigorous evidence base for the health and economic impacts of bariatric surgery for morbidly obese veterans. Results of this study are relevant to patient care in the VA and will assist the VA in managing obese veterans consistent with the 2014 VA/DoD Obesity Clinical Practice Guideline. The evidence generated from these analyses also refine the evidence base for the application of surgical treatment in the national VA Managing Obesity for Veterans Everywhere (MOVE!) program, because these results are more comprehensive and more current results than those generated in our prior HSR&D-funded study of bariatric surgery. This study also provides the most rigorous evidence of the health and economic benefits of bariatric surgery for older male patients who have been under-represented in studies informing the evidence base for bariatric surgery to date.
External Links for this Project
Grant Number: I01HX000420-01A2
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- Maciejewski ML, Raffa S, Gunnar W. Bariatric Surgery and Long-term Durability of Weight Loss: Briefing before the leaders of VA Research, Nursing, Specialty Care, Primary Care Services, Primary Care Operations, Patient Centered Care and Cultural Transformation, Pharmacy Benefits Management, Health Promotion and Disease Prevention, Mental Health Operations, Nutrition and Food Services and Analytics and Business Intelligence.; 2016 Apr 19; Washington, DC. [view]
- Olsen MK. Association Between Bariatric Surgery and Long-Term Survival in Veterans: An Illustration of Sequential Stratification Matching. Paper presented at: Medical University of South Carolina Department of Public Health Sciences Monthly Seminar Series; 2015 Feb 15; Columbia, SC. [view]
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- Maciejewski ML, Livingston E, Smith V, Kahwati L, Henderson W, Arterburn D. Impact of Bariatric Surgery on Survival in a Cohor of Predominantly Older Men. Paper presented at: AcademyHealth Annual Research Meeting; 2011 Jun 12; Seattle, WA. [view]
- Maciejewski ML, Woolson S, Smith V. Simulation Study to Investigate the Impact of Pre-surgical Cost Analysis on Estimating Bariatric Surgery Cost-Effectiveness in the VA System. Poster session presented at: Society of General Internal Medicine Annual Meeting; 2015 Oct 7; Providence, RI. [view]
Health Systems, Diabetes and Other Endocrine Disorders
Treatment - Observational