The influence of polyvascular disease on the obesity paradox in vascular surgery patients

Background: Obesity is a risk factor for atherosclerosis, a polyvascular process associated with reduced survival. In nonvascular surgery populations, a paradox between body mass index (BMI) and survival is described. This paradox includes reduced survival in underweight patients, whereas overweight and obese patients have a survival benefit. No clear explanation for this paradox has been given. Therefore, we evaluated the presence of the obesity paradox in vascular surgery patients and the influence of polyvascular disease on the obesity paradox. Methods: In this retrospective study, 2933 consecutive patients were classified according to their preoperative BMI (kg/m(2)) and screened for polyvascular disease and cardiovascular risk factors before surgery. In addition, medication use at the time of discharge was noted. Outcome was all-cause mortality during a median follow-up of 6.0 years (interquartile range, 2-9 years). Results: BMI (kg/m(2)) groups included 63 (2.3%) underweight (BMI <18.5), 1379 (47.0%) normal (BMI 18.5-24.9, reference), 1175 (40.0%) overweight (BMI 25-29.9), and 311 (10.7%) obese (BMI >= 30) patients. No direct interaction between BMI, polyvascular disease, and long-term outcome was observed. Underweight was an independent predictor of mortality (hazard ratio, 1.65; 95% confidence interval, 1.22-2.22). In contrast, overweight protected for all-cause mortality (hazard ratio, 0.79; 95% confidence interval, 0.700-0.89). Cardioprotective medication usage in underweight patients was the lowest (P < .001), although treatment targets for risk factors were equally achieved within all treated groups. Conclusion: Overweight patients referred for vascular surgery were characterized by an increased incidence of polyvascular disease and required more extensive medical treatment for cardiovascular risk factors at discharge. Long-term follow-up showed a paradox of reduced mortality in overweight patients. (J Vasc Surg 2011;53:399-406.)