Frailty and Arthritis Risk in a Population-Based Cohort: Long-Term Follow-Up and Predictive Model Evaluation.

BackgroundLongitudinal evidence on frailty and subsequent arthritis in China is limited.MethodsWe analyzed 4,615 adults aged ≥45 years from the China Health and Retirement Longitudinal Study (2011-2020), excluding those with baseline physician-diagnosed arthritis. Multivariable logistic regression assessed associations of baseline pre-frailty and frailty with arthritis at follow-up. Sensitivity, discrimination, and exploratory subgroup analyses were performed.ResultsAt follow-up, 1,219 participants (26.4%) reported arthritis. Compared with robust participants, pre-frail (OR = 1.35, 95% CI: 1.14-1.59) and frail participants (OR = 1.63, 95% CI: 1.04-2.55) had higher odds of arthritis. Findings remained directionally consistent in sensitivity analyses. Adding frailty modestly improved discrimination (AUC: 0.588 vs. 0.599; ΔAUC = 0.011; P = 0.017). No interaction remained significant after multiple-testing correction.ConclusionPre-frailty and frailty were associated with higher odds of arthritis after 9 years, supporting frailty as a potential longitudinal risk marker, although its incremental discriminatory value was limited.