Heterogeneous Trajectory of Frailty and Associated Factors among the Middle-Aged and Older People: Evidence from CHARLS 2011-2020

This study aims to investigate the heterogeneity in the developmental trajectories of frailty and to identify associated influencing factors among middle-aged and older adults. Based on China Health and Retirement Longitudinal Study database from 2011 to 2020. This study selected survey data from 9, 442 individuals 45 years and older. Then constructed a latent growth mixture model to identify the trajectories of frailty development, screened for associated factors using health ecological model, and analyzed through multiple stepwise logistic regression. The heterogeneous trajectories of frailty among the middle-aged and older people could be divided into four categories: "C1: Rapid increase (10.14%)", "C2: Slow decline (7.60%)", "C3: Persistent high (11.09%)", "C4: Stable low (71.17%)". Female, aged ≥60 years, disability, obesity, short sleep duration, lack of social activity, rural residence, mid-western region, illiteracy, previously employed, and low-income were identified as the primary risk factors for frailty. Living alone significantly increases the risk of transitioning to the "C1 Rapid increase" group. Conversely, aged 45-59 years, normal BMI, eastern region, being working and having a more satisfying life were protective factors for the "C2: Slow decline" group. (all P<0.05). There is significant heterogeneity in the developmental trajectory of frailty in the middle-aged and older people. It is recommended to identify and implement targeted frailty management as early as possible based on the characteristics of different groups, to effectively prevent or delay the deterioration of frailty in the middle-aged and older people.