Social determinants of health and life expectancy in US adults

Individual unfavorable social determinants of health (SDoH) negatively affect health outcomes, yet the combined impact of multiple SDoH on life expectancy is not well understood. We analyzed data from a nationally representative sample of US adults aged ≥18 years in NHANES (1999–2018) to examine associations between unfavorable SDoH—both individually and in combination—and life expectancy. Among 45,516 participants (mean age 47.7 years; 51.4% women) with a median follow-up of 9.4 years, 6,164 deaths occurred. Four key SDoH—employment, family income, education, and marital status—were individually associated with shorter life expectancy at age 50: unemployment (−4.2 years, 95% CI 3.9–4.6), low income (−3.5, 3.1–3.9), low education (−3.1, 2.7–3.4), and unmarried status (−2.4, 2.1–2.8). Among 16 combined SDoH profiles, participants who were unemployed, low-educated, and unmarried lost 10.8 years compared with the most favorable profile. Notably, education had the largest individual impact, but its effect diminished when combined with other adverse SDoH; well-educated individuals with multiple unfavorable SDoH lost more life years than less-educated counterparts (7.2 vs. 4.9 years). In this nationally representative cohort, four key SDoH strongly influenced life expectancy. Multiple adverse SDoH had additive effects, and the impact of education was context-dependent, emphasizing the importance of considering combined social risk in public health strategies. Unfavorable social determinants of health (SDoH) are associated with poorer health outcomes, but the combined impact of multiple SDoH on life expectancy in the US population remains poorly understood. In a cohort of 45,516 US adults, four key SDoH—employment, family income, education, and marital status—were significantly associated with all-cause mortality and life expectancy. Participants with unfavorable profiles across these SDoH experienced a 10.8-year reduction in life expectancy at age 50. Combination analyses showed that while education is a primary determinant of longevity, its impact is context-dependent when multiple adverse SDoH co-occur. These findings underscore the role of SDoH as upstream determinants of disparities in life expectancy and support the need for comprehensive SDoH monitoring and targeted interventions to reduce health inequities and improve population longevity.