Body-mass index and mortality risk in U.S. blacks compared to whites.

OBJECTIVE

To compare body-mass index (BMI)-related mortality risk in U.S. Blacks vs. Whites as the relationship appears to differ across race/ethnicity groups.

METHODS

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 to 2002 with no history of cardiovascular disease (CVD) or cancer were pooled. 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 4303 deaths (1205 among never smokers). Age-adjusted mortality rates were higher in Blacks compared to Whites at BMI < 25 kg/m2 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 appeared weaker in US Blacks than in Whites, especially among women.