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BACKGROUND/RATIONALE:
Obesity is fast becoming the leading health problem in the United States, with more than 70 million US adults affected. In VA, the prevalence of obesity was 33.1% and the prevalence of class 3 obesity (BMI > 40) was 3.4% in 2000. Obesity is an independent risk factor for type 2 diabetes, coronary heart disease, obstructive sleep apnea, stroke, and several types of cancer. Bariatric surgery is effective in reducing weight and BMI of obese individuals and improving cardiovascular risk factors (e.g., diabetes, hypertension, hyperlipidemia) sufficiently to allow reduction or discontinuation in lipid-lowering, diabetes, hypertension and gastroesophageal reflux (GERD) medications within six-twelve months after surgery. It is unknown whether the weight loss and medication discontinuation induced by bariatric surgery in largely middle-aged
female samples would result in similar improvements in men.
OBJECTIVE(S):
The goal of our proposed short-term research project is to examine the impact of bariatric surgery on weight change and medication discontinuation in a retrospective cohort study of 856 obese veterans who had bariatric surgery and 66,571 obese veterans who did not have bariatric surgery who will be matched to the surgical cases:
Specific Aim 1: For obese veterans who had bariatric surgery in 2000-2006, how much did their weight and BMI change in the months after surgery? Did these changes persist over time?
Specific Aim 2: Compared to non-surgical controls, how much did weight and BMI of obese veterans who had bariatric surgery in 2000-2006 change in the months after surgery? Did these differences persist over time?
Specific Aim 3: Among obese veterans with diabetes or dyslipidemia who had bariatric surgery in 2000-2006, what proportions were able to discontinue their oral hypoglycemic agents or statins in the months after surgery?
METHODS:
The study sample for Aims 1 and 3 will be drawn from the 856 obese veterans from the NSQIP dataset who had bariatric surgery in one of twelve VA bariatric surgical centers in 2000-2006 from the ongoing evaluation of bariatric surgery impacts on survival, VA health care utilization and expenditures (IIR 05-205-1). From the National Center for Health Promotion (NCP) data on year 2000 heights and weights, weve identified 66,571 obese veterans who did not have bariatric surgery that will be matched to the surgical cases by propensity score matching, based on height, weight, age, gender, race, site of care, means test, priority group, marital status, and comorbidity score. The 856 surgical cases would be the focus of Aims 1 and 3, and the cohort of 856 cases and matched cohort of a subset of the 66,571 non-surgical controls would be the focus of Aim 2.
For the Aim 1 analysis in bariatric cases, we will examine percentage change in weight and BMI 24 months after baseline in the 856 bariatric cases in univariate analyses to examine the distribution of weight and BMI change (for regression specification) and to determine if there are patterns of weight loss. We will conduct bivariate analyses with covariates to understand how percentage change in weight and BMI varies by covariates and over time. We will estimate a generalized estimating equation (GEE) of percentage change in weight or BMI as a function of demographics, risk via DCG, smoking status, site and continuous time. For the Aim 2 analysis of the difference between surgical cases and non-surgical controls in percentage change in weight and BMI over 24 months, we will generate similar univariate and bivariate statistics to examine how weight and BMI change differs between cases and controls. We will then estimate a GEE model of weight or BMI change for cases and controls. For the Aim 3 analysis of medication discontinuation in bariatric cases, we will examine discontinuation of oral hypoglycemic agents, anti-hypertensive agents, or statins in the 856 bariatric cases at 3, 6, 12, 18, and 24 months after surgery. We will examine univariate analyses to examine the distribution of discontinuation by medication and conduct bivariate analyses with covariates to understand how weight change varies by covariate and over time. We will then estimate a GEE model, based on a binomial distribution and logit link.
FINDINGS/RESULTS:
No results at this time.
IMPACT:
Investigation of these aims would illustrate the extent to which bariatric surgery for obese veterans results in sustained weight loss and medication discontinuation, which has not be examined extensively in male surgical cases. When coupled with our larger ongoing analysis of survival, VA health care utilization and VA expenditures, this short-term project would provide a comprehensive assessment of the health and economic impacts of bariatric surgery in VA. Given that veteran demand for bariatric surgery vastly outpaces its availability, these results could help the VA Bariatric Surgery Workgroup within the Office of Patient Care Services, VA Central Office and VA leadership determine whether this surgery should be made available to more veterans in more VA medical centers. If we should find that relatively minor weight loss results in substantially improved comorbidity control, we might more vigorously pursue lap band operations-these generally result in less weight loss than RYGB but are much safer operations with fewer short and long term complications than RYGB, which is the current VA standard.
PUBLICATIONS:
None at this time.
DRA:
Chronic Diseases, Health Services and Systems
DRE:
Resource Use and Cost, Treatment
Keywords:
Cost effectiveness, Obesity, Outcomes
MeSH Terms:
none
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