Decomposing socioeconomic differences in self-rated health and healthcare expenditure by chronic conditions and social determinants.

Background: Lower socioeconomic status is associated with lower self-rated health and higher healthcare expenditure. This study identifies which chronic conditions and social determinants contribute most to socioeconomic differences in self-rated health and healthcare expenditure.

Methods: Registry and survey data combining 3 socioeconomic indicators (income, education, and financial welfare), 26 social determinants, 20 chronic conditions, age, sex, self-rated health, and healthcare expenditure for 135,183 Dutch individuals aged 25-65, were linked at individual level. Oaxaca-Blinder decomposition analyses were conducted to quantify the relative contributions of chronic conditions and social determinants to socioeconomic differences in self-rated health and healthcare expenditure.

Results: Poorer self-rated health and higher healthcare expenditure among lower income groups were partly attributable to a higher prevalence of chronic conditions (33% and 70%, respectively). Acid-related disorders, cardiovascular diseases and psychological disorders contributed most to both differences in self-rated health and healthcare expenditure. Social determinants almost completely accounted for income differences in self-rated health. Social determinants explained more than the observed difference in healthcare expenditure between income groups, suggesting that, when adjusted for social determinants, lower income groups would have lower healthcare expenditure than higher income groups. Including both chronic conditions and social determinants in a single decomposition indicated that income security & social protection (28%), social & human capital (26%), and chronic conditions (23%) were equally important to income differences in self-rated health. For healthcare expenditure, chronic conditions and social determinants each accounted for approximately half of the socioeconomic differences.

Conclusions: Social determinants outside the healthcare sector accounted for almost all of the socioeconomic differences in self-rated health. This highlights the need for integrated policies across multiple domains, such as the social, economic and healthcare sector, to reduce avoidable health inequalities. Given that socioeconomic differences in healthcare expenditure were primarily associated with chronic conditions, prioritizing prevention of chronic conditions among lower socioeconomic groups can potentially reduce healthcare spending within this group and improve the healthcare system's sustainability and affordability.