Associations of socioeconomic position and depression with frailty among older adults: Cross-sectional evidence from 17 countries.

OBJECTIVES: This study describes the cross-national variation in socioeconomic disparities in frailty among older adults, assesses whether depression mediates the relationship between socioeconomic position and frailty, and examines the extent of the interactive or joint effects of depression and socioeconomic position on frailty.

STUDY DESIGN: A cross-sectional analysis was conducted using population-based data from five aging cohorts across 17 countries. Frailty was assessed using the modified Fried Frailty Phenotype scale, which comprises five domains. Educational level and total household income were used to measure socioeconomic position. Multivariable logistic regression was used to calculate the odds ratios and 95 % confidence intervals for the associations, and pooled odds ratios were estimated using a random-effect meta-analysis. Mediation and interaction analyses explored the association between socioeconomic position, depression, and frailty.

RESULTS: Among the 104,136 adults (mean age 64.29 years), 27,115 were frail. The prevalence of frailty varied widely across countries (Switzerland, 6.00 %; India, 46.51 %). Participants occupying a low socioeconomic position had a significantly higher risk of frailty than those in higher socioeconomic positions, with the association more pronounced in high-income countries. Depression mediated 30.9 % of the association between socioeconomic position and frailty. A significant additive interaction of low socioeconomic position and depression on frailty (1.98) was observed. Individuals occupying a low socioeconomic position who had depression had a markedly higher risk of frailty than those in a high socioeconomic position and no depression.

CONCLUSIONS: Socioeconomic disparities in frailty vary across countries. The combined effects of socioeconomic position and depression highlight the need for integrated interventions to reduce frailty and promote healthy, equitable aging globally.