Lower extremity function trajectories in the African American health cohort

Background. We addressed two understudied issues in estimating lower extremity functional trajectories in older adults-incorporating the effect of mortality and evaluating heterogeneity among African Americans. Methods. Data were taken from the 998 participants in the African American Health cohort. A highly reliable and valid 8-item lower extremity function scale was used at baseline and at the 1-, 2-, 3-, 4-, 7-, and 9-year follow-up interviews. Semiparametric (ie, discrete) group-based mixture modeling identified the trajectories, and multinomial logistic regression identified risk factors for differential trajectory groups. Results. When treating mortality as informative censoring, six discrete trajectories were observed with 45% of the participants belonging to three stable trajectories (good, fair, or poor function), and the remainder belonging to three declining trajectories (very high function with minimal improvement then minimal decline, very good function with a slow and modest decline, and very good function with a large and quick decline). Conclusion. Substantial heterogeneity in lower extremity function trajectories exists in the African American Health cohort, after appropriately treating mortality as informative censoring.