Socioeconomic inequalities in healthy ageing: functional capacity and community participation in older adults across 22 countries

BACKGROUND: Maintaining functional capacity and social participation is essential for healthy ageing, yet the association between socioeconomic status (SES) and these outcomes across diverse global contexts remains inadequately quantified. METHODS: This cross-sectional analysis used harmonised individual-level data from eight longitudinal ageing studies across 22 countries in adults aged ≥ 60 years (n = 70 189). A composite SES index was derived from education and household wealth. Associations between SES and three ICF-based outcomes (muscle strength, physical performance, and community participation) were assessed using multilevel mixed-effects logistic regression to account for the nested structure of the data. RESULTS: Among 70 189 participants (median age 68 years [IQR 63-74]; 50.9% female), strong inverse socioeconomic gradients were observed across all outcomes. Compared with the highest SES group, the lowest SES group had significantly increased odds of low muscle strength (adjusted odds ratio [aOR], 1.92; 95% CI, 1.81-2.03), poor physical performance (aOR, 1.78; 95% CI, 1.44-2.20), and low community participation (aOR, 3.91; 95% CI, 3.07-4.75; P < 0.001 for trend for all). The odds of co-occurring impairments were substantially elevated under low SES conditions, most notably for simultaneous impairment in all three domains (aOR, 9.78; 95% CI, 8.29-11.53; P < 0.001). Socioeconomic gradients varied by country income level, being most pronounced for muscle strength in low-income countries, physical performance in middle-income countries, and community participation in high-income countries. CONCLUSIONS: SES is a fundamental determinant of healthy ageing, shaping outcomes across muscle strength, physical performance, and community participation. These findings highlight measurable SES disparities in functional capacity across diverse global contexts and provide a robust evidence base for equity-focused interventions to reduce ageing-related functional decline.