Relationship of race-ethnicity, body mass index, and economic strain with longitudinal self-report of physical functioning: the Study of Women's Health Across the Nation.

PURPOSE: This study examined progression and improvement of physical functioning limitations during the mid-life and whether race-ethnicity, economic strain, or body mass index were associated with these changes.
METHODS: Women from the Study of Women's Health Across the Nation with one or more measure of self-reported physical functioning, categorized as no, some, or substantial limitations, between study visits 4 and 12 were included (n = 2497).
RESULTS: When women were aged 56-66 years, almost 50% reported limitations in functioning. African American women were more likely to report substantial (odds ratio, 1.63; 95% confidence interval, 1.06-2.52) and Chinese women were more likely to report some limitations (odds ratio, 2.03; 95% CI, 1.22-3.36) compared with Caucasian women. Economic strain and obesity predicted limitations. The probability of worsening ranged from 6% to 22% and of improving ranged from 11% to 30%. Caucasian and Japanese women had the highest probability of remaining fully functional (80% and 84%, respectively) compared with 71% of African American women.
CONCLUSIONS: Race-ethnicity, obesity, and economic strain were associated with prevalence and onset of physical functioning limitations. Functional improvement is common, even among vulnerable subgroups of women. Future studies should characterize predictors of decline and improvement so that interventions can sustain functioning even in the context of many known immutable risk factors.