Socioeconomic disparities in physiological dysregulation: a longitudinal mediation analysis of cardiometabolic multimorbidity among middle-aged and elderly Chinese

BACKGROUND: Cardiometabolic multimorbidity (CMM) poses a significant health burden among middle-aged and older adults in China, yet early risk prediction remains challenging. The Composite Score of Physiological Variability (CSPV), integrating blood pressure, pulse rate, and body weight fluctuations, may offer a novel tool for assessing CMM risk, but the role of socioeconomic status (SES) in this association is unclear. METHODS: Using data from the China Health and Retirement Longitudinal Study (CHARLS, N = 4,905) and the Chinese Longitudinal Healthy Longevity Survey (CLHLS, N = 4,086), we calculated CSPV based on tertile-coefficients of variation for physiological measures. Cox models and mediation analyses examined longitudinal associations between CSPV and CMM, adjusting for covariates (age, sex, lifestyle, etc.), and quantified SES mediation. RESULTS: The risk of CMM was significantly higher for each 1-point increase in CSPV (CHARLS: HR = 1.31, 95% CI: 1.18-1.42; CLHLS: HR = 1.18, 95% CI: 1.06-1.31; combined analyses: HR = 1.22, 95% CI: 1.12-1.37). SES played a partially mediating role in the association between CSPV and CMM partially mediated, with mediation percentages of 21% (CHARLS) and 16% (CLHLS), respectively. Stratified analyses showed that the CSPV-CMM association was stronger in the low-education, low-income, and rural-dwelling populations. CONCLUSION: Elevated CSPV is an independent predictor of increased risk of CMM in middle-aged and elderly Chinese, and SES plays an important mediating role in this association. Monitoring the variability of physiological indicators and combining them with socioeconomic interventions may contribute to the early prevention and control of CMM.