Estimating Hospitalization Incidence for Ischaemic Heart Disease Using National Health Insurance Claims Data

Objectives: The objective of this study is to estimate the hospitalization incidence for ischemic heart disease (IHD) in South Korea using data from the National Health Insurance Service (NHIS). Additionally, the study aims to evaluate the appropriateness of the estimation method by examining the estimated incidence and its distribution across demographic characteristics.Methods: Data were obtained from the NHIS, with a focus on inpatient data to avoid potential overestimation by excluding mild cases. IHD episodes were defined in three stages, with criteria progressively broadened to include secondary diagnoses, related procedures, and medication codes. Using age-standardised rates and stratified demographic variables, detailed IHD incidence rates were derived.Results: The 2021 IHD incidence rate exhibited variation across stages, with the strictest criteria yielding a rate of 117.6 per 100,000 and broader definitions resulting in a rate of 125.1. Increased rates were observed among males, older adults, and low-income groups. Rural areas exhibited elevated incidence rates, reflecting regional disparities in healthcare access. Age-standardised rates enabled consistent comparisons, highlighting critical areas for targeted healthcare resources and preventive programs.Conclusions: Although claims data have limitations, such as excluding out-of-hospital mortalities, the NHIS database offers comprehensive population coverage for reliable long-term monitoring and health policy development. By refining episode definitions and standardising age, this study provides an evidence-based framework for assessing the burden of IHD, informing resource allocation, and guiding prevention strategies in high-risk areas. The findings support the use of IHD incidence rates as a valuable basis for public health planning and resource distribution.