[Multimorbidity developmental trajectory among middle-aged and older adults and its impact on new-onset disability in...

Objective: To explore the developmental trajectory of multimorbidity and its impact on new-onset disability to identify homogeneous groups with similar multimorbidity developmental courses and to provide evidence for interventions for disability risk among middle-aged and older adults in China. Methods: Data was retrospectively collected from China Health and Retirement Longitudinal Study with four consecutive surveys (2011-2018). Group-based trajectory modeling was used to fit multimorbidity developmental trajectories, and the impact of multimorbidity trajectories on new-onset disability was analyzed using the time-dependent Cox regression model. Results: A total of 8 580 participants were included in current analysis, and four multimorbidity trajectories were identified: no multimorbidity (n=2 136, 24.90%), newly-developing (n=3 758, 43.80%), moderate-developing (n=2 270, 26.45%) and severe-developing (n=416, 4.85%). Participants who belong to moderate-developing and severe-developing tended to be female, single, overweight or obese, live in rural areas, have poorer self-rated health and high levels of annual per capita household expenditure, and developed a new-onset disability. After adjusting for demographic and behavioral covariates, compared to the newly-developing, the severe-developing(HR=3.132, 95%CI:1.884-5.207) had the highest risk of disability, followed by the moderate- developing (HR=1.400, 95%CI:1.026-1.909) and the risk for the no multimorbidity (HR=0.631, 95%CI:0.424-0.938) was the lowest. Conclusions: There was great heterogeneity in the developmental trajectory of multimorbidity among middle-aged and older adults in China. Data showed that the risk of disability in the developmental trajectory of multimorbidity increases with increasing levels. We think that the elevating developmental trajectory of multimorbidity is a risk factor for developing disability.