Inventory of real-world data sources in Japan: Annual survey conducted by the Japanese Society for Pharmacoepidemiology Task Force

Purpose: The Database Task Force of the Japan Society for Pharmacoepidemiology began its annual surveys of databases available for clinico and pharmacoepidemiological studies in 2010. In this report, we summarize the characteristics of the databases available in Japan based on the results of our 2021 survey to illustrate the recent developments in the infrastructure for database research in Japan. Methods: We included 20 major databases from the academia, government, or industry that were accessible to third parties. We used a web-based questionnaire to ask the database providers about their characteristics, such as their organization, data source(s), numbers of individuals enrolled, age distribution, code(s) used, and average follow-up periods. Results: We received responses from all 20 databases approached: eight hospital-based databases, six insurer-based databases, four pharmacy-based databases, and two in the "other" category. Among them, 17 contained information from medical claims, pharmacy claims, and/or Diagnosis Procedure Combination data. Most insurer databases contained health check-up data that could be attached to the claims component. Some hospital-based databases had data from electronic medical records. Most insurer-based databases collected data from the insurers of working-age employees and therefore had limited coverage of older people. Most databases coded their medication data using the Japanese reimbursement codes, and many provided Anatomical Therapeutic Chemical Classification codes. Conclusions: The number of databases available for clinico and pharmacoepidemiological research and the proportion of the population they cover are increasing in Japan. The differences in their characteristics mean that the appropriate database must be selected for a particular study purpose.