Racial and ethnic differences in obesity and overweight as predictors of the onset of functional impairment.

OBJECTIVES: To examine racial and ethnic differences in the effects of body mass index (BMI) on the onset of functional impairment over 10 years of follow-up.
DESIGN: Longitudinal analyses of a cohort from a nationally representative survey of community-dwelling American adults.
SETTING: Six waves (1996-2006) of the Health and Retirement Study (HRS). PARTICIPANTS: Two groups of HRS participants aged 50 and older without functional impairment at baseline (1996): 5,884 with no mobility difficulty and 8,484 with no activity of daily living (ADL) difficulty. MEASUREMENTS: Mobility difficulty was a composite measure of difficulty walking several blocks, walking one block, climbing several flights of stairs, and climbing one flight of stairs. ADL difficulty was measured as difficulty in dressing, bathing or showering, eating, and getting in and out of bed without help. The association between baseline BMI and risk of developing functional impairment was estimated using generalized estimating equation models.
RESULTS: Overweight and obesity were significant predictors of functional impairment. Overweight and obese Hispanics were 41% and 91% more likely, respectively, to develop ADL disability than whites in the same BMI categories. Overweight and severely obese blacks were also more likely than their white counterparts to develop ADL disability. Risk of developing ADL difficulty was higher for Hispanics than for blacks in the obese category. No significant differences in onset of mobility difficulty were found between racial or ethnic groups within any BMI category.
CONCLUSION: Blacks and Hispanics were at higher risk than whites of ADL but not mobility impairment. In addition to weight control, prevention efforts should promote exercise to reduce functional impairment, especially for blacks and Hispanics, who are at higher risk.