Body-Mass Index and Mortality Risk in US Blacks Compared to Whites

OBJECTIVE: To compare body-mass index (BMI)-related mortality risk in US Blacks vs. Whites as the relationship appears to differ across race/ethnicity groups. DESIGN AND METHODS: We pooled cross-sectional surveys of nationally representative samples of 11,934 Blacks and 59,741 Whites aged 35–75 in the National Health Interview Survey from 1997–2002 with no history of cardiovascular disease or cancer. Mortality follow-up was available through 2006. BMI was calculated from self-reported height and weight. We used adjusted Cox regression analysis to adjust for potential confounders. RESULTS: Over 9 years of follow-up, there were 4,303 deaths (1,205 among never smokers). Age-adjusted mortality rates were higher in Blacks compared to Whites at BMI < 25 kg/m(2) and showed no increase at higher levels of BMI. In men, adjusted hazard ratios for all-cause death rose in a similar fashion across upper BMI quintiles in Blacks and Whites; in women, however, BMI was positively associated with mortality risk in Whites, but inversely associated in Blacks (p interaction = 0.01). Racial disparities were amplified in subsidiary analyses that introduced a 12-month lag for mortality or focused on CVD mortality. CONCLUSIONS: The relationship of elevated BMI to mortality appears weaker in US Blacks than in Whites, especially among women.