Cumulative social determinants of health and frailty risk in older adults

Frailty is a growing global health challenge, leading to increased rates of adverse outcomes and higher healthcare costs. Its prevalence is particularly high among older adults. This study examined the relationship between social determinants of health (SDoH) and frailty in older adults. This study included 9,933 participants aged ≥ 65 years from the repeated cross-sectional National Health and Nutrition Examination Survey (NHANES), using data from 2003 to 2018, with different individuals sampled in each cycle. Weighted logistic regression models were used to examine the association between frailty and eight SDoH variables: education level, employment status, poverty-income ratio, food security, health insurance, access to healthcare, homeownership, and marital status. Stratified analyses were also conducted. Nonlinear associations were assessed using restricted cubic spline models. As a sensitivity analysis, we additionally examined the association between cumulative SDoH and pre-frailty (frailty index 0.10–0.20), using non-frail individuals as the reference group. Of the participants, 3,868 were classified as frail, with a weighted total of 12,619,578 cases. Logistic regression revealed a 37% increase in the odds of prevalent frailty risk for each additional SDoH risk factor (AOR = 1.37; P < 0.001). The cumulative number of unfavorable SDoH was positively associated with frailty risk (P for trend < 0.001). Stratified analyses indicated that the impact of cumulative unfavorable SDoH on frailty was more pronounced in those aged 65–75 years (P for interaction < 0.001). In a sensitivity analysis using pre-frailty as the outcome, the associations with cumulative SDoH were weaker and not consistently significant. This study suggests that unfavorable SDoH are significantly associated with higher odds of frailty in older adults (≥ 65 years), with a more pronounced association in those aged 65–75 years.