Utilization analysis of laboratory tests using health insurance claims data: advancing nationwide diagnostic stewardship monitoring systems.

Objectives: Diagnostic stewardship aims to optimize laboratory testing practices by ensuring appropriate test utilization while minimizing unnecessary testing. However, the nationwide monitoring systems for laboratory test utilization remain underdeveloped. In this study, we analyzed nationwide health insurance claims data to identify inappropriate test utilization patterns and inform diagnostic stewardship interventions.

Methods: We analyzed the health insurance claims data from the Health Insurance Review and Assessment Service of Korea from January 2018 to December 2023. Three laboratory tests with concerns were evaluated. Inappropriate test utilization was classified based on adherence to recommended methodologies and institutional testing practices.

Results: The proportion of tuberculosis cultures performed using both liquid and solid media increased from 84.6 % in 2018 to 91.4 % in 2023; however, some institutions continued to perform >90 % of tests using only a single medium. Regional disparities were observed, with nonmetropolitan areas exhibiting higher rates of inappropriate tuberculosis testing. Stool ova and parasite tests showed a persistent reliance on direct smear-only methods. The correlation between endemic parasitic regions and the high proportions of direct smear-only tests suggests an urgent need for improved diagnostic methodologies. Despite longstanding recommendations against their use, bleeding time tests remained frequently ordered. The total number of bleeding time test claims exceeded 400,000 annually, with a limited decline over time.

Conclusions: Systematic monitoring frameworks based on nationwide claims data can identify inappropriate test utilization and support diagnostic stewardship efforts by informing targeted interventions, thereby optimizing laboratory resource allocation and enhancing patient safety.