The association of socioeconomic status and social participation with intrinsic capacity: findings from cross-sectional and longitudinal analyses in CHARLS

Background Socioeconomic status (SES) and social participation (SP) influence intrinsic capacity (IC) in older adults. This study examined their impact on IC using CHARLS data. Methods Cross-sectional analysis included 10,390 CHARLS 2011 participants, with 3,008 for longitudinal evaluation (2011–2015). Univariate and multivariate Cox and logistic regression models examined the relationship between socioeconomic status (SES), social participation (SP), and intrinsic capacity (IC). Nonlinear associations were assessed using restricted cubic spline (RCS) modeling, and stratified analyses explored demographic differences. Least absolute shrinkage and selection operator (LASSO) regression identified key predictors for IC, and a nomogram was developed. Results Among the 10,390 participants included in the analysis, 6,756 (65.0%) were classified as having impaired IC. In all 3 models, SES and SP were both independent protective factors for IC in cross-sectional analysis (odds ratio < 1, P  < 0.001). In longitudinal analysis, the graded protective association of SES with IC was consistent with that in cross-sectional analysis, but only for higher SP (hazard ratio < 1, P  < 0.001). Both SES and SP demonstrated marked inverse associations with IC, which were either linear or nonlinear. The importance of SES and SP in predicting IC was further highlighted by the fact that LASSO regression revealed SP and SES as the top 2 predictors. Moreover, the nomogram established based on top 7 most important variables in LASSO exhibited good predictive performance. Conclusion SES and SP were identified as protective factors for IC, enhancing precaution of impaired IC and supporting healthy aging in older adults. Trial registration Not applicable.