Association of Body Surface Area versus Body Mass Index on Outcomes in Peripheral Arterial Disease

Background: Numerous studies have indicated that increased obesity in patients with established peripheral artery disease (PAD) is inversely associated with disease prognosis, a phenomenon coined as the "obesity paradox". A major cause of criticism in studies investigating the obesity paradox is the use of body mass index (BMI) as a surrogate marker in defining and quantifying the degree or severity of obesity. We conducted a retrospective review to verify whether the obesity paradox persists in patients with PAD when using body surface area (BSA) as an alternative anthropometric measure. Methods: Patients undergoing surgery (open or endovascular) for PAD between January 2009 and March 2020 were identified from the Vascular Quality Initiative (VQI) national database. The association between BSA or BMI and risk of postoperative complications was evaluated using logistic regression and restricted cubic spline analysis, both of which were adjusted for demographic and comorbid risk predictors. When analyzing BSA and BMI as categorical variables, patients were grouped according to BSA quintiles and the World Health Organization (WHO) Results: A total of 130,428 patients were included based on our eligibility criteria, of which 85,394 (65.5%) were men. Patients were typically hypertensive (87.8%), diabetic (50.4%), and overweight (63.0% over 25 kg/m2). Patients with a high BMI or BSA typically presented at a younger age and with greater preoperative administration of drugs (statin, angiotensin converting enzyme inhibitor, anticoagulant, and beta blocker). Our results indicate that BSA and BMI are inversely associated with postoperative risk of all-cause morbidity, mortality, and cardiac complications. This finding was displayed when analyzing BMI or BSA as a continuous variable or when indexing patients into BMI or BSA groups. Conclusions: Our data suggests that the obesity paradox persists in patients with PAD when using either BMI or BSA as anthropometric measures. Future studies with a prospective design and utilizing newer anthropometric indices should be conducted to fully verify the presence of this phenomenon.