This study investigated the association between insurance status and postoperative mortality using South Korean national data. The data included 540���422 patients aged 20 to 64 treated at 958 facilities. To calculate odds ratios (ORs) for in-hospital and 30-day mortality post-admission, generalized estimating equation (GEE) logistic regression was used. Significantly lower ORs for in-hospital mortality (0.55; 95% confidence interval [CI] = 0.50-0.61) and 30-day mortality post-admission (0.59; 95% CI = 0.54-0.64) were found among subscribers with "employee insured" status than among those who were self-employed or Medical Aid beneficiaries. Significantly higher ORs for in-hospital mortality (1.45; 95% CI = 1.33-1.57) and 30-day mortality post-admission (1.46; 95% CI = 1.34-1.59) were observed among those with a <25% premium than in those with a ���75% premium. The risk of both in-hospital and 30-day post-admission mortality consistently increased with declining socioeconomic status, confirming the presence of inequality.
