Effect of weight loss on predicted cardiovascular risk: change in cardiac risk after bariatric surgery.

Objective: Our goal was to assess the effect of bariatric surgery on cardiovascular risk estimations of preventable, long-term adverse outcomes.

Methods: We performed a population-based, historical cohort study between 1990 and 2003 of 197 consecutive patients from Olmsted County, MN, with Class II to III obesity (defined as BMI > or = 35 kg/m2) treated with Roux-en-Y gastric bypass and 163 non-operative patients assessed in a weight-reduction program. We used the observed change in cardiovascular risk factors and risk models derived from data from the National Health and Nutrition Examination Survey (NHANES) I and the NHANES I Epidemiological Follow-up Study (NHEFS) to calculate the predicted impact on cardiovascular events and mortality for the operative and non-operative groups.

Results: Mean follow-up was 3.3 years. Hypertension, diabetes, and dyslipidemia all improved after bariatric surgery. The estimated 10-year risk for cardiovascular events for the operative group decreased from 37% at baseline to 18% at follow-up, while the estimated risk for the non-operative group did not change from 30% at baseline to 30% at follow-up. Risk modeling to predict 10-year outcomes estimated 4 overall deaths and 16 cardiovascular events prevented by bariatric surgery per 100 patients compared with the non-operative group.

Conclusions: Bariatric surgery induces an improvement in cardiovascular risk factors in patients with Class II to III obesity. Weight loss predicts a major, 10-year reduction in cardiovascular events and deaths. Bariatric surgery should be considered as an alternative approach to reduce cardiovascular risk in patients with Class II to III obesity.