Association of multimorbidity trajectories from early adulthood through middle age with middle-age physical function

BACKGROUND: Chronic conditions can develop early in the adult life course and accumulate at different rates. However, the association between multimorbidity trajectory groups from young adulthood and physical function in midlife has not been well studied. METHODS: Data are from 2018 Coronary Artery Risk Development in Young Adults (CARDIA) study participants who completed a PROMIS Function Short Form and five physical performance tests (gait speed, grip strength, balance, chair stands, 6-minute-walk, composite score range 0-20, higher is better). Multimorbidity trajectory groups were previously identified using latent class growth models and characterized by the age of onset and rapidity of accumulation of conditions: (1) early-50s, slow (E50S), (2) mid-40s, fast (M40F), (3) mid-30s, fast (M30F), (4) late-20s, slow (L20F), (5) mid-20s, slow (M20S), and (6) mid-20s, fast (M20F). The association of multimorbidity trajectory group with physical function scores in middle age were estimated using multiple linear regression. RESULTS: At the time of physical function measurement, participants had a mean age (SD) of 60.0 (3.6) years, 58.2% were female, and 44.4% were Black. Compared to participants in the E50S class, adjusted mean differences in the PROMIS score were -1.37, -1.44, -3.18, and -2.53 for those in the M40F, M30F, L20F, and M20F, respectively (all P-values <.01). Compared to E50S adjusted mean differences in the composite performance scores were -1.48, -0.44, and -1.51 for L20F, M20S, and M20F, respectively (all P-values <.05). CONCLUSIONS: Earlier onset and more rapid accumulation of chronic conditions from early adulthood may identify those at risk for functional limitations in midlife.