Prompt reduction in use of medications for comorbid conditions after bariatric surgery

Background: Bariatric surgery leads to weight loss, but it is unclear whether surgery reduces conditions associated with obesity. We explored this by assessing the change in use of medications to treat diabetes mellitus, hypertension, and hyperlipidemia in the year following surgery. Methods: This is a cohort study using administrative data from 2002 to 2005 from seven Blue Cross/Blue Shield Plans. We compared the mean number of medications at the time of surgery and in the subsequent year. Medication usage by surgical patients was also compared to usage by matched enrollees without surgery but with a propensity score suggesting obesity. With Poisson and logistic regression, we tested for statistical differences in usage, accounting for repeated measures and controlling for age, sex, and diabetes. We also evaluated medications expected to be less influenced by surgery (antidepressants, thyroid replacement, and antihistamines). Results: Our cohort included 6,235 enrollees with bariatric surgery. Their mean age was 44 years with 82% women; 34% had diabetes. Medication use declined significantly by 3 months. By 12 months after surgery, medication use for diabetes, hypertension, and hyperlipidemia had declined by 76%, 51%, and 59%, respectively. In contrast, thyroid hormone, antihistamine, and antidepressant use decreased by only 6%, 15%, and 9%, respectively. Enrollees without surgery had a modest increase in medications for diabetes, hypertension, and hyperlipidemia of 4%, 8%, and 20%, respectively. Conclusions: Medication use for three serious obesity-associated conditions decreased promptly following surgery. The clinical and economic benefits of reduced medication requirements should be considered when making decisions about the effects of bariatric surgery.