Physical functioning and survival: Is the link weaker among Latino and black older adults?

Measures of physical functioning are among the strongest predictors of mortality, but no previous study has assessed whether the predictive value of such measures varies by race/ethnicity, as has been done for the simple self-rated health question. The current study tests whether the relationship between two measures of physical functioning (the number of self-reported functional limitations and measured walking speed) and mortality is weaker (has a lower hazard ratio) for Latinos and blacks than for whites. Data were drawn from the 1998-2014 waves of the Health and Retirement Study, with mortality follow-up through 2016. We used Cox hazard models with household random effects to test for interactions between race/ethnicity and these measures of physical functioning and verified earlier findings for self-rated health. The number of self-reported functional limitations is significantly related to mortality for all racial/ethnic groups, but has a substantially lower hazard ratio for blacks and Latinos than for whites, as hypothesized. This hazard ratio remains lower for blacks and Latinos after adjustment for sociodemographic characteristics and health conditions. These findings suggest that the higher rates of functional limitations observed among Latinos and blacks compared with whites may reflect a history of strenuous physical work, inadequately controlled pain, lower leisure-time physical activity, or untreated/under-treated mobility problems that can lead to reduced physical performance without necessarily having a substantial effect on mortality risk. On the other hand, we do not detect significant racial/ethnic differences in the association between measured walking speed and subsequent mortality. This may be the result of the smaller sample size for the walking speed tests, the more nuanced nature of the continuous walking speed measure, or the fact that the walking speed test captures only a subset of the limitations included in the self-reports.