The association between continuing work after retirement and the incidence of frailty: evidence from the China health and retirement longitudinal study

Objectives: Retirement represents a significant life transition, with post-retirement status serving as a pivotal aspect of aging research. Despite its potential significance, little research has delved into the relationship between continuing work after retirement and the frailty. This study aims to investigate the association between continuing work after retirement and the incidence of frailty among older individuals. Design: A nationally representative cohort study. Setting and participants: We utilized data from 4 waves (2011, 2013, 2015 and 2018) of the China Health and Retirement Longitudinal Study and a total of 5,960 participants were included in the study after applying specific inclusion and exclusion criteria. Methods: Frailty was assessed using a Frailty Index. To balance baseline covariates between workers (n = 3,170) and non-workers (n = 2,790), we employed inverse propensity of treatment weighting. The relationship between work status and the incidence of frailty was examined using Cox proportional hazards analysis, with results reported as hazard ratios and 95% confidence intervals. Results: A total of 5,960 participants (mean age 64 years; 42.1% male) were included in the analysis. Over a mean follow-up of 6.9 years, 2,105 cases of frailty were identified. In the cohort analysis, following adjustment using the inverse propensity of treatment weighting (IPTW), continuing work after retirement showed a negative association with frailty incidence, with an HR of 0.72 (95% CI, 0.65−0.79). Subgroup analysis revealed a more significant protective effect of continuing work beyond retirement age among individuals aged 65 or older, males, smokers, and those with limited social activities. Conclusions: In summary, this study identified a significant association between continuing work after retirement and a decreased risk of frailty. The findings underscore the potential benefits of policies promoting social engagement and extending working life in enhancing the quality of life for the aging population.