Effect of Body Mass Index on Activity Limitation and Mortality Among Older Women: The National Health Interview Survey, 1986–1990

We assessed the impact of body mass on the association between activity limitations due to chronic conditions and mortality among 24,612 noninstitutionalized white or African American women aged > or = 65 years who participated in a National Health Interview Survey between 1986 and 1990. We found that more African American women had activity limitations than white women (59% vs 46%, respectively). The difference by race was greatest (19% vs 10%) for the most severe limitation (unable to perform the major activity). For women aged 65-69, the major activity was working or keeping house; for those aged > or = 70, it was the ability to live independently. For white women in all three categories of body mass index (BMI) and for African American women with BMI 15%-85%, the risk of dying was significantly higher for those unable to perform the major activity than for those with no limitations, controlling for the effects of education, marital status, and perceived health. The findings confirm the established link between low BMI and mortality and between activity limitations and mortality. Additionally, the findings further suggest that activity limitations linked to chronic conditions increase the risk of death within each stratum of BMI after adjusting for potential confounders.