Area-Level Socioeconomic Inequalities in Intracranial Injury-Related Hospitalization in Korea: A Retrospective Analysis of Data From Korea National Hospital Discharge Survey 2008-2015

Although inequality in traumatic brain injury (TBI) by individual socioeconomic status (SES) exists, interventions to modify individual SES are difficult. However, as interventions for area-based SES can affect the individual SES, monitoring or public health intervention can be planned. We analyzed the effect of area-based SES on hospitalization for TBI and revealed yearly inequality trends to provide a basis for health intervention. We included patients who were hospitalized due to intracranial injuries (ICIs) between 2008 and 2015 as a measure of severe TBI with data provided by the Korea National Hospital Discharge Survey. Area-based SES was synthesized using the 2010 census data. We assessed inequalities in ICI-related hospitalization rates using the relative index of inequality and the slope index of inequality for the periods 2008-2009, 2010-2011, 2012-2013, and 2014-2015. We analyzed the trends of these indices for the observation period by age and sex. The overall relative indices of inequality for each 2-year period were 1.82 (95% confidence interval, 1.5-2.3), 1.97 (1.6-2.5), 2.01 (1.6-2.5), and 2.01 (1.6-2.5), respectively. The overall slope indices of inequality in each period were 38.74 (23.5-54.0), 36.75 (21.7-51.8), 35.65 (20.7-50.6), and 43.11 (27.6-58.6), respectively. The relative indices of inequality showed a linear trend for men ( = 0.006), which was most evident in the ≥ 65-year age group. Inequality in hospitalization for ICIs by area-based SES tended to increase during the observation period. Practical preventive interventions and input in healthcare resources for populations with low area-based SES are likely needed.