A review of studies using the Japanese National Database of Health Insurance Claims and Specific Health Checkups

BACKGROUND Electronic health databases are increasingly used for research purposes. The Japanese National Database of Health Insurance Claims and Specific Health Checkups (NDB) is a large national administrative claims database. We reviewed published original articles that used the NDB. METHODS Studies published from January 2011 to June 2019 using the NDB were identified through PubMed and the academic product lists of the NDB, following the PRISMA guidelines. RESULTS 68 studies were included in our review (43 were in English and 25 were in Japanese). The first NDB study in English was published in 2015, which was 4 years after the NDB was released for research purposes. The average annual growth rate of the number of NDB stud‐ ies in English was 237% after the first publication of an NDB study in English. Descriptive studies were the most common study design (n = 42), and the Clinical Medicine was the most common research area (n = 18). The study strength most frequently mentioned by authors of the NDB studies was the large sample size. In terms of limitations, authors most frequently mentioned the lack of important data and validation studies. CONCLUSIONS Since its release, the NDB has increasingly attracted attention, and the number of studies using the NDB has grown rapidly. The large sample size and wide array of health care data in the NDB enabled researchers to conduct health service research in various research areas with several study designs. Finally, our review suggests to policy makers that administrative database should be constructed and managed with the environment which promote researchers access to the database and link it to other databases. Although the protection of respondents’ privacy should be carefully considered, higher accessibility and data linkage may maximize the potential of the administrative database and may enable researchers to produce more valuable health service researches for policy making in health care.