Sarcopenia as a risk factor for incident pain in Chinese middle-aged and older adults: longitudinal evidence from the CHARLS cohort

OBJECTIVES: This study aimed to prospectively examine sarcopenia as a risk factor for incident pain in middle-aged and older Chinese adults, analyze independent associations between subcomponents of sarcopenia (low muscle mass, handgrip strength, and physical performance) and incident pain, and evaluate subgroup specificities. DESIGN: Prospective cohort study. SETTING: Nationwide, using data from the China Health and Retirement Longitudinal Study (CHARLS) waves 2011, 2013, and 2015. PARTICIPANTS: 3,148 adults aged 45 years and older without pain at baseline. MEASUREMENTS: Sarcopenia was defined per AWGS 2019 criteria, incorporating appendicular skeletal muscle mass (ASM), handgrip strength, and physical performance (gait speed and chair stand test). Incident pain was assessed using standardized self-reported questions from the CHARLS questionnaire. Cox proportional hazards models estimated hazard ratios (HR) and 95% confidence intervals (CI), adjusted for age, sex, residence, marital status, education, smoking, alcohol consumption, hypertension, diabetes, stroke, heart disease and depression. Restricted cubic splines (RCS) explored exposure-response relationships, and subgroup analyses assessed interactions. RESULTS: Pain incidence was 35.93%, possible sarcopenia 60.23%, and sarcopenia 34.37%. Sarcopenia was associated with a 52% higher hazard of incident pain (fully adjusted HR = 1.52, 95% CI: 1.10-2.10, p = 0.011). For the subcomponents of sarcopenia, only low muscle mass showed a positive association with incident pain risk in the fully adjusted model (HR = 1.21, 95% CI: 1.06-1.38, p = 0.005). Subgroup analyses showed that sarcopenia status interacted with education status and depression (both P for interaction