In South Korea, the ICD-10(International Classification of Diseases-10), which was developed by the World Health Organization, was translated, and its translated version has been locally adapted. However, the ICD-10 is appropriate for use only in tertiary hospitals. Thus, a complementary classification is required for primary medical institutions driven by frequent outpatient care. Furthermore, the need for diverse and subdivided healthcare statistics containing reasons for encounter, healthcare processes, diagnosis for the purpose of management, and prevention of diseases at the national level is increasing.

We examined and analyzed medical records of patients who visited primary care physicians by using the ICPC-2(International Classification of Primary Care-2), which is capable of patient-focused classification, and compared the results with those obtained using the ICD-10. Thereby, this study aimed to determine 1) which between ICD-10 and ICPC-2 is superior, 2) whether the parallel use of the two classifications is needed, 3) whether a third classification is needed, and 4) problems of the current fee-for-service system, under which claims with ICD-10 disease code at the first day of outpatient visit should be filed at the National Health Insurance Corporation.