Sex differences in functional limitations and the role of socioeconomic factors: a multi-cohort analysis

Abstract

Background: Women are more likely to have functional limitations than are men, partly because of greater socioeconomic disadvantage. However, how sex differences vary by severity of functional limitations remains unclear. We examined sex differences in functional limitations, with attention to socioeconomic factors and severity of limitations.

Methods: Longitudinal data on limitations in basic activities of daily living (ADL) and instrumental activities of daily living (IADL) and mobility activities were drawn from 62 375 participants from 14 countries. For ADL, IADL, and mobility, participants were categorised based on number of limited activities (0, 1, 2, or ≥3). 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 and labour force status).

Findings: The prevalence of IADL and ADL limitations was higher in women than in men. After adjustment for socioeconomic factors, this sex difference was attenuated. The sex difference in IADL limitations at age 75 years (in the 1895-1929 cohort) was 3·7% before adjustment for socioeconomic factors (95% CI 2·6-4·7) and 1·7% (1·1-2·2) after adjustment. For ADL, the sex difference in limitations at age 75 years (in the 1895-1929 cohort) was 3·2% (2·3-4·1) before adjustment for socioeconomic factors and 1·4% (0·9-1·8) after adjustment. Sex differences in mobility limitations (16·1%, 95% CI 14·4-17·7) remained after adjustment for socioeconomic factors (14·3%, 12·7-15·9). After age 85 years, women were more likely to have three or more IADL or mobility limitations and men were more likely to have one or two limitations.

Interpretation: Socioeconomic factors largely explain sex differences in IADL and ADL limitations but not mobility. Sex differences in mobility limitations in midlife are important targets for future research and interventions.

Funding: National Institute on Aging, UK National Institute for Health Research, European Commission, and US Social Security Administration.

Figure 1

Sex differences in the probability of ≥1 mobility, IADL, and ADL limitation The top panels show the probability of having ≥1 functional limitation plotted by age for men and women in each birth cohort. The bottom panels show the sex difference in the probability of having ≥1 functional limitation. A positive value indicates women have a greater probability than men. Predicted probabilities are based on models adjusted for sex, age, birth cohort, and their interactions, marital status, study, and region and plotted for reference categories for all covariates. ADL=activities of daily living. IADL=instrumental activities of daily living.

Figure 2

Sex differences in probability of mobility limitations by number of limitations The top panels show the probability of the given number of mobility limitations plotted by age for men and women in each birth cohort. The bottom panels show the sex difference in the probability of having a limitation. Positive values indicate women have a greater probability than men of having a given number of limitations. Predicted probabilities are based on models adjusted for sex, age, birth cohort, and their interactions, marital status, study, region, education, and labour force status and plotted for reference categories for all covariates.

Figure 3

Sex differences in probability of IADL limitations by number of limitations The top panels show the probability of having the given number of IADL limitations plotted by age for men and women in each birth cohort. The bottom panels show the sex difference in the probability of having limitations. Positive values indicate women have a greater probability than men of a given number of limitations. Predicted probabilities are based on models adjusted for sex, age, birth cohort, and their interactions, marital status, study, region, education, and labour force status and plotted for reference categories for all covariates. IADL=instrumental activities of daily living.

Figure 4

Sex differences in probability of ADL limitations by number of limitations The top panels show the probability of having the given number of ADL limitations plotted by age for men and women in each birth cohort. The bottom panels show the sex difference in the probability of having limitations. Positive values indicate women have a greater probability than men of a given number of limitations. Predicted probabilities are based on models adjusted for sex, age, birth cohort, and their interactions, marital status, study, region, education, and labour force status and plotted for reference categories for all covariates. ADL=activities of daily living.