Social frailty independently predicts 9-year mortality among community-dwelling older adults in Mexico: validation of a brief social frailty index

Introduction: Social frailty, defined as deficits in social resources, roles, and engagement, is an emerging risk dimension. However, evidence on its measurement and prognostic value in Latin America is limited. Methods: Using nationally representative data from the Mexican Health and Aging Study (2012-2021), we adapted a five-item Social Frailty Index (SFI) and evaluated its psychometric properties and association with 9-year all-cause mortality in 5,400 community-dwelling adults aged ≥60 years. Results: At baseline, 38.9% were pre-frail (SFI = 1) and 25.2% were frail (SFI ≥ 2). Mortality increased progressively across categories. In fully adjusted Cox models, pre-frailty (HR = 1.21, 95%CI: 1.06-1.37) and frailty (HR = 1.56, 95%CI: 1.36-1.79) independently predicted higher mortality risk. Discussion: The SFI, adapted to available MHAS data, demonstrated prognostic relevance. This provides initial evidence supporting further research on social frailty assessment in the region, including cultural adaptation and external validation.