Intergenerational socioeconomic origin-destination patterning and frailty burden in middle-aged and older Chinese...

To examine whether intergenerational socioeconomic origin-destination patterning was associated with frailty burden and change in burden over time.

Longitudinal cohort study using 2011-2018 data from the China Health and Retirement Longitudinal Study, including 2574 adults aged 45 years or more with complete mobility classification and baseline variables.

Repeated 32-item frailty index values and binary frailty were analysed using generalized estimating equations and latent growth curve models. Additional analyses separated origin and destination socioeconomic status and excluded depressive symptoms and related constructs from the frailty index.

The cohort was predominantly middle aged at baseline (median age 51 years; 86.2% aged 45-59 years), and 8.0% met the frailty criterion. Compared with stable-low socioeconomic status, upward mobility was associated with a lower repeated frailty index (coefficient - 0.022, 95% confidence interval - 0.032 to -0.011; P < 0.001) and lower odds of frailty (odds ratio 0.55, 95% confidence interval 0.37 to 0.80; P = 0.002). Downward mobility and stable-high status were also associated with lower continuous frailty index values. Both origin and destination status contributed to the pattern, whereas the unweighted common mobility term was not statistically significant. Group differences were concentrated in baseline frailty levels, with no significant differences in annual frailty change. Results were similar after excluding depressive symptoms and related constructs from the frailty index.

Intergenerational socioeconomic patterning was associated mainly with frailty burden already present at baseline. The findings support a life-course origin-destination interpretation rather than a causal effect of socioeconomic mobility.