State Racism Index and physical function: The REasons for Geographic and Racial Differences in Stroke (REGARDS) study.

Structural racism contributes to health inequities in the United States. This study aimed to quantify the association between state racism index (SRI) and physical function. In a national United States community-based cohort study, 13 661 non-Hispanic Black and White adults who had baseline information (2003-2007), SRI data (2006-2010) and physical function data (2013-2016) were included. Physical function measurements included activities of daily living (ADL), instrumental activities of daily living (IADL), timed walk, and chair stand test. Multivariable generalized regression models (GLMs) and linear regression models were used to evaluate the association between SRI and physical function. Interactions with age, sex, and region were evaluated. Among Black participants, each unit increase in SRI was significantly associated with 2% higher IADL scores (ratio of means [95% confidence interval, CI]: 1.018 [1.007, 1.029]) indicating worse function. This association attenuated after adjustment for socioeconomic factors but was stronger in the United States Stroke Belt region (p for interaction < .05). Among White participants, higher SRI was significantly associated with 2% ADL and 1% IADL lower scores (ratio of means [95% CI]: 0.983 (0.969, 0.997) and 0.985 (0.977, 0.994), respectively) indicating better function. This association was independent of socioeconomic and health-related factors. We did not observe an association between SRI and timed walk or chair stands overall or by race. Higher state-level structural racism was associated with worse physical function among Black participants and better physical function for White participants. Associations were influenced by socioeconomic factors and magnified in southern United States.