Study data
We analysed the National Patients Sample (NPS) data from the Korean Health Insurance Review and Assessment (HIRA) Service from 2018 (HIRA-NPS-2018-0078). HIRA is a repository of claims data collected for reimbursement purposes.23 HIRA-NPS data, a nationally representative sample of whole beneficiaries, were extracted with sex- and age-stratified random sampling methods from all patients who used medical services in 2018.24 The data comprise the complete insurance claim data of 3% of the general population.24
Diagnostic information for HIRA-NPS was coded according to the Korean Standard Classification of Diseases version 7 (KCD-7), which is based on the International Classification of Diseases 10th Revision (ICD-10). HIRA-NPS data contain fields representing the individual patient characteristics (age, sex, and type of insurance), medical institutions (type of institution and region), and outpatient and inpatient clinical management (medical procedures and medications).
The Institutional Review Board (IRB) of Pusan National University approved this study (PNU IRB/2021_29_HR). This study used secondary data obtained from the HIRA and contained no personal information; therefore, written consent was waived by the IRB.