Adiposity and risk of stroke: body shape matters more than body weight.

Background: Higher body mass index (BMI) and larger waist circumference (WC), characteristics of increased adiposity, are associated with greater risk of cardiovascular disease (CVD). However, an obesity paradox (improved survival in those with history of stroke) has been observed in some populations. We hypothesized that BMI would be associated with decreased risk of stroke but that this association would be attenuated after accounting for WC. Methods: The REasons for Geographic and Racial Differences in Stroke (REGARDS) study recruited 30,239 black and white participants age 45 years and older from across the United States between 2003 and 2007. WC, height and weight were measured during a baseline in home visit and participants were followed every 6 months. Strokes were adjudicated by physicians after review of medical records. Cox proportional hazards models were used to assess stroke risk. BMI and WC were modeled in quintiles. Results: We observed 1047 incident and recurrent strokes over a mean of 6.3 years. Higher BMI and lower WC were associated with decreased risk of stroke after adjustment for demographic and medical risk factors (Table). Having both BMI and WC in the model dramatically increased the strength of association for the other variable. Collinearity was not present. The observed association was consistent across race, sex, age, WC, and history of stroke (all p for interaction >0.20). Conclusion: Increased BMI, the main measure used to define obesity, was not a stroke risk factor. Increased risk of stroke was observed in WC less than the current recommendations of 88 cm for women and 102 cm for men. Smaller waist sizes and maintenance of lean mass are important targets for stroke prevention.<br [ABSTRACT FROM AUTHOR]