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The Health, Aging, and Body Composition (Health ABC) Study

Lisa Fredman, PhD; Jane A. Cauley, DrPH; Suzanne Satterfield, MD, DrPH; Eleanor Simonsick, PhD; S. Melinda Spencer, PhD; Hilsa N. Ayonayon, PhD; Tamara B. Harris, MD, MPH; for the Health ABC Study Group

Arch Intern Med. 2008;168(19):2154-2162.

Background  Although caregivers report more stress than noncaregivers, few studies have found greater health decline in older caregivers. We hypothesized that caregivers may be more physically active than noncaregivers, which may protect them from health decline.

Methods  The sample included 3075 healthy adults from the Health, Aging, and Body Composition (Health ABC) Study. They were aged 70 to 79 years in April 1997 to June 1998 and resided in Memphis, Tennessee, or Pittsburgh, Pennsylvania. Caregivers (680 [22.1%]) were participants who provided regular care or assistance for a child or a disabled or sick adult. Outcomes included all-cause mortality and incident mobility limitation (defined as difficulty walking one-quarter mile or climbing 10 steps on 2 consecutive semiannual contacts) during 8 years. Total physical activity included daily routine, exercise, and caregiving activity.

Results  Overall, 20.6% of caregivers died and 50.9% developed mobility limitations vs 22.0% and 48.9% of noncaregivers, respectively. Associations differed by race and sex. Mortality and mobility limitation rates were 1.5 times higher in white caregivers (eg, among white female caregivers, adjusted hazard ratio for mortality, 1.6; 95% confidence interval, 1.0-2.5) but not for black female caregivers vs noncaregivers (adjusted hazard ratio for mortality, 0.9; 95% confidence interval, 0.5-1.4). Physical activity mediated these associations in most race-sex groups. High-intensity caregivers (ie, caregiving 24 hours per week) had elevated rates of decline when adjusted for physical activity but lower rates when not adjusted for activity.

Conclusion  Older white caregivers have poorer health outcomes than black female caregivers. Physical activity appears to mask the adverse effects of high-intensity caregiving in most race-sex groups.

Author Affiliations: Department of Epidemiology, Boston University School of Public Health, Boston, Massachusetts (Dr Fredman); Department of Epidemiology, University of Pittsburgh, Pittsburgh, Pennsylvania (Drs Cauley and Spencer); Department of Preventive Medicine, University of Tennessee, Memphis (Dr Satterfield); Clinical Research Branch, National Institute on Aging, Baltimore, Maryland (Dr Simonsick); Department of Epidemiology and Biostatistics, University of California, San Francisco (Dr Ayonayon); and Laboratory of Epidemiology, Demography, and Biometry, National Institute on Aging, Bethesda, Maryland (Dr Harris).