The association between subjective well-being and physical-psychological-cognitive multimorbidity: a longitudinal analysis of a nationally representative survey

While subjective well-being (SWB) significantly influences individual physical and mental health, its impact on complex multimorbidity remains unclear. This study aimed to investigate the effect of SWB on physical-psychological-cognitive multimorbidity (PPC-MM). Using data from four waves (2011, 2013, 2015, and 2018) of the China Health and Retirement Longitudinal Study, we employed discrete-time survival models (pooled logistic regression with complementary log-log link) as the primary analysis to examine the association between SWB and incident PPC-MM, accounting for interval-censored data. Marginal structural models (MSMs) with inverse probability weighting were used to handle time-varying SWB and confounding. Competing risks were addressed via Fine-Gray models, with death as a competing event. Sensitivity analyses included physical-cognitive multimorbidity (PC-MM) only and continuous-time Cox models. Among 6843 participants (mean age 59 ± 9 years), 1585 (23.2%) reported being "satisfied" with life at baseline, 1088 (15.9%) reported "Not satisfied," and the remainder reported "somewhat satisfied." Significant differences were observed across SWB groups in age, sex, education, residence, marital status, smoking, alcohol consumption, sleep duration, body mass index, and waist circumference (all p < 0.05). In fully adjusted discrete-time models, polynomial contrasts revealed a strong linear trend associating lower SWB with increased PPC-MM risk (HR = 2.03, 95% CI 1.82-2.26, p < 0.001) and slight non-linearity (quadratic HR = 1.24, 95% CI 1.15-1.34, p < 0.001). Time-varying MSMs confirmed causal effects (linear HR = 1.95, 95% CI 1.73-2.19, p < 0.001; quadratic HR = 1.22, 95% CI 1.12-1.33, p < 0.001). Fine-Gray models yielded similar subdistribution HRs (linear sHR = 1.26, 95% CI 1.12-1.40, p < 0.001; quadratic sHR = 1.11, 95% CI 1.02-1.20, p < 0.05), with cumulative incidence functions diverging across groups (p < 0.001). Results remained robust across multiple sensitivity and subgroup analyses. SWB exerts a significant influence on the development of PPC-MM among middle-aged and older adults in China over time. These findings underscore the importance of incorporating SWB into lifecourse preventive strategies against PPC-MM.