Early-life socioeconomic position and the accumulation of health-related deficits by midlife in the 1958 British birth cohort study

Reducing population levels of frailty is an important goal and preventing its development in mid-adulthood could be pivotal. Childhood socioeconomic position (SEP) is associated with a myriad of adult health outcomes but evidence is limited on associations with frailty. Using 1958 British birth cohort data (N=8711), we aimed to: (i) establish the utility of measuring frailty in mid-life, by examining associations between a 34-item frailty index at 50y (FI 50y ) and mortality over an eight-year follow-up period and (ii) examine associations between early-life SEP and FI 50y and investigate whether these associations were explained by adult SEP. Hazard ratios (HRs) for mortality increased with increasing levels of frailty, e.g., HR sex-adjusted was 4.07(95% CI:2.64,6.25) for highest vs. lowest fifth of FI 50y . Lower early-life SEP was associated with higher FI 50y per unit decrease in early-life SEP (on a 4-point scale), FI 50y increased by 12.7%(10.85%,14.6%) in a model adjusted for early-life covariates. After additional adjustment for adult occupational class and education, the association attenuated to 5.71%(3.71%,7.70%). Findings suggest that early-life SEP is associated with frailty and that adult SEP only partially explains this association. Results highlight the importance of improving socioeconomic circumstances across the life course to reduce inequalities in frailty from mid-adulthood.