Dynamic transitions between arthritis and elevated depressive symptoms in older Chinese adults: a 9-year longitudinal analysis of CHARLS

Arthritis and elevated depressive symptoms frequently coexist in later life, yet analyses based on a single baseline state and subsequent event cannot distinguish onset, symptom improvement, progression to comorbidity, and persistence. We characterised repeated transitions between arthritis and elevated depressive symptoms and examined origin-wave factors associated with five prespecified next-wave outcomes. We analysed five waves (2011–2020) of the China Health and Retirement Longitudinal Study. Participants aged 60 years or older at baseline were classified at each wave as having neither condition, arthritis only, elevated depressive symptoms only (CESD-10 score ≥ 10), or comorbidity. Arthritis was carried forward after the first reported physician diagnosis. Five transition-specific logistic generalised estimating-equation models were fitted to adjacent-wave person-intervals. Stabilised inverse-probability-of-observation weights were used to account for measured predictors of next-wave state availability. Models included origin-wave pain burden, sleep duration, instrumental activities of daily living, social participation, other multimorbidity, demographic and behavioural factors, continuous CESD-10 score, and survey interval. Of 7,560 age-eligible participants, 6,923 had a classifiable baseline state and 6,115 contributed 18,080 adjacent-wave person-intervals. At baseline, 19.4% had comorbidity. Across intervals, 30.6% of arthritis-only intervals progressed to comorbidity and 66.5% of comorbid intervals remained comorbid. Multisite pain (≥ 2 sites versus none) was associated with incident arthritis (adjusted odds ratio [aOR] 2.09, 95% confidence interval [CI] 1.61–2.72), incident elevated depressive symptoms (aOR 1.48, 95% CI 1.23–1.77), arthritis only to comorbidity (aOR 1.40, 95% CI 1.19–1.65), elevated depressive symptoms only to comorbidity (aOR 1.92, 95% CI 1.39–2.67), and next-wave persistence of comorbidity (aOR 1.27, 95% CI 1.07–1.50). Short sleep was associated with both single-condition-to-comorbidity transitions and comorbidity persistence. Arthritis and elevated depressive symptoms changed across survey waves, although comorbidity often persisted. Multisite pain was associated with all five prespecified next-wave outcomes, whereas short sleep and functional impairment were associated mainly with progression to, or persistence of, comorbidity. Repeated assessment of pain, depressive symptoms, sleep, and function may help identify older adults more likely to experience unfavourable next-wave transitions; causal effects require prospective or interventional evaluation.