Life-course risk factors are associated with activity of daily living disability in older adults.

Background: Multiple risk factors accumulate over the life-course and contribute to higher rates of disability at older ages. This study investigates whether three life-course risk factors (low educational attainment, poor health in childhood and multimorbidity) are associated with increased risk of disability [defined as any limitation in basic activities of daily living (BADL)] in older adults and whether this relationship is moderated by the national socioeconomic context, measured by the Human Development Index (HDI).

Methods: Data include 100 062 adults (aged 50 and over) participating in longitudinal studies of aging conducted in 19 countries. Analyses include multivariable Poisson models with robust standard errors to assess the associations between HDI, life-course risk factors and other individual-level control variables (sex and age) with any BADL disability.

Results: In country-specific analyses, both educational attainment and multimorbidity are independently associated with disability in nearly every country. The interaction between these risk factors further increases the magnitude of this association. In pooled regression analyses, the relationship between life-course risk factors and disability is moderated by a country's HDI. For individuals with all three life-course risk factors, the predicted probability of disability ranged from 36.7% in the lowest HDI country to 21.8% in the highest HDI country.

Conclusions: Social and health system policies directed toward reducing the development of life-course risk factors are essential to reduce disability in all countries, but are even more urgently needed in those with lower levels of socioeconomic development.