Body mass index and the risk of incident noncommunicable diseases after starting antiretroviral therapy.

OBJECTIVES: Obesity and HIV infection are associated with an increased incidence of noninfectious comorbid medical conditions, but the relationship between body mass index (BMI) and the development of noncommunicable diseases (NCDs) among individuals on antiretroviral therapy (ART) has not been well characterized.
METHODS: A cohort study of adults initiating ART between 1998 and 2010 at an academic centre with systematic laboratory and clinical data collection, including AIDS and NCD diagnoses, was carried out. The relationship between BMI at ART initiation and the risk of incident cardiovascular, hepatic, renal or oncological NCDs was assessed using Cox proportional hazard models. BMI was fitted using restricted cubic splines and models adjusted for age, sex, race, CD4 count, protease inhibitor use, year of initiation, and prior AIDS-defining illness.
RESULTS: Among 1089 patients in the analysis cohort, 54% had normal BMI, 28% were overweight, and 18% were obese. Baseline BMI was associated with developing an incident NCD (P<0.01), but the relationship was nonlinear. Compared with a BMI of 25 kg/m(2) , a BMI of 30 kg/m(2) conferred a lower risk of an incident NCD diagnosis [adjusted hazard ratio (AHR) 0.59; 95% confidence interval (CI) 0.40, 0.87]. This protective effect was attenuated at a BMI of 35 kg/m(2) (AHR 0.78; 95% CI 0.49, 1.23). Results were similar in sensitivity analyses incorporating tobacco, alcohol and illicit drug use, statin and antihypertensive exposure, and virological suppression.
CONCLUSIONS: Overweight individuals starting ART have a lower risk of developing NCDs compared with normal BMI individuals, which may reflect a biological effect of adipose tissue or differences in patient or provider behaviours.