Effectiveness of Case Management for High-Frequency Outpatients and Long-Term Inpatients Among South Korean Medical Aid Beneficiaries.

South Korea implemented a case management program for Medical Aid (MA) beneficiaries in 2003. This study evaluates the effect of case management on healthcare utilization among MA beneficiaries, with a focus on both outpatients and inpatients. This retrospective comparative study was conducted using the 2023 full dataset of MA beneficiaries. The propensity score matching method was used to match the case management group with the non-case management group, and differences in healthcare utilization were analyzed using a difference-in-differences analysis. The case management group exhibited characteristics of a medically vulnerable population, with greater healthcare needs than those of the non-case management group. Case management interventions reduced outpatient days by 4.7 and outpatient medical costs by USD 327 per person annually. For long-term inpatients, it reduced inpatient days by 13.6 and medical costs by USD 2261 per person annually ( < 0.001). MA case management effectively reduced both outpatient/inpatient days and medical costs. As the effects may vary depending on the type of case management, developing diverse and detailed case management programs is necessary.