Double disparities of the excess risks and costs of extreme temperatures on hospitalization between Medical Aid and non-Medical Aid populations in South Korea.

Abstract

Background: Previous studies have reported simple differences in extreme temperature-related health risks by low socioeconomic status; however, few have examined in depth the double disparities in the socially marginalized people by age groups, sexes, disabilities, and causes of hospitalization. This study examined (i) the differences between heat- and cold-related risks on hospitalization between people who are eligible and non-eligible for the medical aid system in the national health insurance service system and (ii) differences between the heat- and cold-related risk and cost differences by specific subgroups in South Korea.

Methods: We collected population-based longitudinal cohort data from the National Health Insurance Service-National Health Insurance Database from 2010 to 2019. The data included all individuals who were eligible for the Korean Medical Aid (MA) system during the study period and we used their data on hospitalization through the emergency department (ED). As a control group, we collected age-sex-residential address-matched individuals who were not eligible for the MA system. We adopted a case-crossover design with a distributed lag nonlinear model to evaluate the excess risks and costs associated with cold and heat temperatures on hospital admissions via the emergency room department.

Results: During the study period, 509 480 hospital admissions via the ED were recorded among 1 466 176 beneficiaries who were eligible for MA. Among the MA beneficiaries, the estimated risk for ED admission that was attributable to heat was 1.19 [95% confidence interval (CI): 1.14-1.24] and the risk that was attributable to cold temperature was 1.52 (95% CI: 1.43-1.61), which were both higher than those of the control groups that incorporated matched beneficiaries who were not eligible for MA. For both heat and cold, the difference between MA and non-MA was prominent in non-elderly populations, males, people with disabilities, and admissions with mental and cardiovascular diseases.

Conclusion: This study revealed the hypothesis that the differences between heat- and cold-related risks in the socially marginalized population existed and suggested that the disparities might also be disproportionate by socioeconomic and demographic statuses.