Sex differences in functional limitations and the effect of socioeconomic factors: a retrospective multi-cohort study

Abstract

BackgroundWomen are more likely to have functional limitations (ie, limitations in activities of daily living) than men, partly due to sex differences in socioeconomic factors. How changes in sex differences in socioeconomic factors in successive birth cohorts have affected functional limitations is unclear. We aimed to examine sex differences in functional limitations, with attention to the effect of socioeconomic factors. MethodsIn this retrospective multi-cohort study, we analysed data on limitations in activities of daily living, instrumental activities of daily living (IADL), and mobility activities from four longitudinal cohort studies on ageing (the English Longitudinal Study of Ageing; the Irish Longitudinal Study on Ageing; the Survey of Health, Ageing and Retirement in Europe; and the Health and Retirement Study) spanning 1–9 periods of data collection over 17 years. 62 375 participants (including 34 452 [55%] women) aged 50–107 years from 14 countries were included. Sex differences in limitations in four birth cohorts (1895–1929, 1930–38, 1939–45, and 1946–60) were analysed before and after adjustment for socioeconomic factors (education level and work status) using mixed effects ordinal logistic models with an age timescale. FindingsSex differences in mobility increased from age 50 to 70 years and in IADL until age 90 years and decreased thereafter. Sex differences in ADL limitations remained substantially similar with age but varied by birth cohort (sex by birth cohort interaction p<0·0001). Sex differences in IADL and ADL limitations were minor after adjustment for socioeconomic factors. The sex difference in limitations at age 75 (1895–1929 cohort) for IADL was 3·7% (95% CI 2·6–4·7) before and 1·7% (1·1–2·2) after adjustment for socioeconomic factors, and for ADL was 3·2% (2·3–4·1) before and 1·4% (0·9–1·8) after adjustment. Sex differences remained for mobility after adjustment (16·1%, 14·4–17·7) before adjustment versus 14·3% (12·7–15·9) after. InterpretationSocioeconomic factors explained the majority of sex differences in IADL and ADL limitations but not mobility limitations, with women reporting more mobility limitations than men aged 50 years or older. Efforts to reduce sex differences in disability should focus on identifying and targeting drivers of sex disparities in mobility limitations from midlife. FundingNational Institute on Aging, UK National Institute for Health Research, European Commission, US Social Security Administration.