Structural health vulnerability and functional limitation among Mexican adults: a nationally representative cross-sectional analysis of ENSANUT 2024

Abstract Background Structural deprivations, including educational lag, lack of access to health services, and material poverty, are widespread in Mexico and frequently co-occur, yet health research has examined these conditions almost exclusively in isolation, missing the compounding effect of simultaneous deprivations. This study introduces the Structural Health Vulnerability Index (SHVI), a composite counting index based on the Alkire-Foster methodology and examines its dose-response association with functional limitation in a nationally representative Mexican sample. Methods We analysed cross-sectional data from ENSANUT 2024 (Encuesta Nacional de Salud y Nutricion) ( N = 11,283 adults aged 20 years and older; weighted N: 75.1 million). The SHVI was constructed across three domains: educational deprivation, health-system access exclusion, and socioeconomic position deprivation, with structural vulnerability defined as deprivation in two or more domains (score ≥ 2), following the Alkire-Foster dual cutoff approach. Functional limitation was assessed using the Washington Group Short Set on Functioning (WG-SS), providing internationally comparable functional limitation estimates. Survey-weighted logistic regression models were estimated, adjusted for age, sex, and multimorbidity. Results Weighted functional limitation prevalence was 8.2%. Prevalence rose in a dose-response pattern from 5.4% among adults with no deprivations to 14.6% among those with all three, with more than double the odds at full deprivation. Approximately 21.7 million adults were identified as structurally vulnerable. SHVI effects were not significant in adults aged 20–39 years but were statistically significant from midlife onwards, though the formal SHVI × age group interaction did not reach statistical significance ( p = 0.284). The relative gradient was not significantly different between men and women, though women’s higher baseline prevalence translated into a consistently greater absolute burden. Educational deprivation showed the strongest association; health-system access exclusion was not independently significant after adjustment. Conclusions Structural deprivations co-occur and are associated with functional limitation in a dose-response pattern among Mexican adults, with structurally vulnerable adults facing 75% higher adjusted odds of functional limitation. The SHVI effect was statistically significant from midlife onwards, and the absolute burden was greater among women. The SHVI may provide a replicable population-level framework for identifying structurally vulnerable groups, with potential implications for intersectoral policy and health equity monitoring.