Wealth and occupation determine health deficit accumulation onset in Europe - Results from the SHARE study

While socio-economic characteristics have been shown to be associated with health deficit accumulation (DA) trajectories, their effect on the age at DA onset remains unclear. The objective of this study was to compare the median age at DA onset across nine European countries and to investigate the effects of income, occupation and wealth on DA onset after age 50. We used population samples aged 50 years and older from the SHARE (Survey of Health, Aging and Retirement in Europe) study. Participants from nine European countries with longitudinal data from at least three of the 2004/05, 2006/07, 2010/11, 2012/13 and 2014/15 waves were included in the analysis. A Frailty Index (FI, range 0-1) was constructed from 50 health deficits. DA onset was defined as having FI values > 0.08 in at least two consecutive measurements following an initial FI value ≤ 0.08. We investigated the effect of income, occupation and wealth on DA onset using a random effects model for time-to-event data. Potential confounding variables were identified using directed acyclic graphs. Out of 8616 (mean age 62 years, 49.0% female) participants initially at risk, 2640 (30.6%) experienced a subsequent DA onset. Median age at onset was 71 years overall, ranging from 66 years (Germany) to 76 years (Switzerland). Wealth and occupation were found to have significant effects on DA onset which decreased with age. In sum, the median age at DA onset differs between European countries. On an individual-level, wealth and occupation, but not income influence the age at DA onset.