Frailty Transition and Risk of New-Onset Arthritis Among Adults Aged 45 Years and Older: A Longitudinal Analysis of...

Background: Frailty is a fluctuating health state that may worsen or improve over time and is linked to adverse outcomes, including musculoskeletal disorders such as arthritis. However, evidence on whether frailty changes predict arthritis onset remains limited. This study examined the relationship between changes in frailty status and incident arthritis among Chinese adults aged 45 years and older. Methods: We performed a longitudinal cohort analysis using data from the China Health and Retirement Longitudinal Study (CHARLS). Frailty was quantified with a 30-item Frailty Index (FI) and categorized as robust, pre-frail, or frail. Frailty transitions were defined by changes in FI-based categories across survey waves. Incident arthritis was identified as self-reported physician-diagnosed arthritis during follow-up. Associations between frailty transitions and arthritis onset were evaluated using Cox regression, reporting hazard ratios (HRs) and 95% confidence intervals (CIs). Models were adjusted for demographic characteristics, health behaviors, and biochemical indicators, and sensitivity analyses were conducted to verify result stability. Results: Among 4982 participants (mean age 58.97 years; 45.58% female). Relative to robust individuals, baseline pre-frailty (HR 1.67, 95% CI 1.41-1.97) and frailty (HR 2.76, 95% CI 1.97-3.85) were associated with higher arthritis risk. Participants whose frailty status worsened from robust to pre-frail or frail also showed higher arthritis risk (HR 1.68, 95% CI 1.34-2.10). In contrast, transitions from frail to pre-frail or robust were associated with lower risk (HR 0.44, 95% CI 0.21-0.92). Higher cumulative frailty burden and greater frailty progression were also associated with increased arthritis risk. Conclusions: Frailty transitions are strongly associated with incident self-reported physician-diagnosed arthritis. Monitoring frailty trajectories may improve arthritis risk stratification and support prevention strategies.