Socioeconomic Inequalities in the Economic Burden of Chronic Diseases: Evidence from NHANES 2011–2018

Abstract

Chronic noncommunicable diseases impose substantial and unequally distributed financial pressure on households, yet evidence on how income scarcity interacts with chronic disease complexity to shape the economic burden remains limited. This study analyzes nationally representative data to quantify whether the financial burden borne by adults with multimorbidity rises disproportionately at the lower end of the income distribution. Leveraging NHANES 2011–2018 for sociodemographic and clinical profiles and MEPS for annual medical spending, we estimate a survey-weighted log-expenditure model in MEPS that includes an income × disease interaction and then map the coefficients to NHANES individuals to obtain predicted annual expenditure; we compute the expenditure-to-income ratio (EIR), catastrophic spending at 10% and 20% of income, EIR quantiles, and Gini coefficients to profile affordability and concentration. Results show a clear two-dimensional gradient: within each disease stratum, EIRs are systematically higher in lower-income groups, and within each income stratum, EIRs increase from no chronic disease to single condition and then to multimorbidity; the lowest-income adults with multimorbidity exhibit the highest catastrophic-spending prevalence and the most unequal expenditure distributions. The interaction terms are jointly significant, indicating compounding disadvantage at the intersection of low income and multimorbidity. These findings underscore the need to pair integrated multimorbidity management with income-linked financial protection so that recurrent out-of-pocket outlays do not translate into unsustainable household burdens.