Nationwide Long-Term Evaluation of Polypharmacy Reduction Policies Focusing on Older Adults in Japan

Prevalence of urgent hospitalizations caused by adverse drug reactions: a cross-sectional study

Adverse drug reactions account for a substantial portion of emergency hospital admissions. However, in the last decade, few studies have been conducted to determine the prevalence of hospitalization due to adverse drug reactions. Therefore, this cross-sectional study was conducted to determine the proportion of adverse drug reactions leading to emergency hospital admission and to evaluate the risk factors for these reactions. A total of 5707 consecutive patients aged > 18 years who were emergently hospitalized due to acute medical illnesses between June 2018 and May 2021 were included. Causality assessment for adverse drug reactions was performed by using the World Health Organization-Uppsala Monitoring Centre criteria. The median patient age was 78 years (IQR 63-87), and the proportion of women was 47.9%. Among all the hospitalizations, 287 (5.0%; 95% confidence interval (CI) 4.5-5.6%) were caused by 368 adverse drug reactions. The risk factors independently associated with hospitalization due to adverse drug reactions were polypharmacy (OR 2.66), age ≥ 65 years (OR 2.00), and ambulance use (OR 1.41). Given that the population is rapidly aging worldwide, further efforts are needed to minimize hospitalizations caused by adverse drug reactions.

Literature Review of Studies Using the National Database of the Health Insurance Claims of Japan (NDB): Limitations and Strategies in Using the NDB for Research

The use of the National Database of Health Insurance Claims and Specific Health Checkups of Japan (NDB) for research has increased over time. Researchers need to understand the characteristics of the data to generate quality-assured evidence from the NDB. In this review, we mapped and characterized the limitations and related strategies using the NDB for research based on the descriptions of published NDB studies. To find studies that used Japanese healthcare claims data, we searched MEDLINE, EMBASE, and Ichushi-Web up to June 2023. Additionally, we hand-searched the NDB data publication list from the Ministry of Health, Labour and Welfare (2017-2023). We abstracted data based on the NDB data type, research themes, age of the study sample or population, targeted disease, and the limitations and strategies in the NDB studies. Ultimately, 267 studies were included. Overall, the most common research theme was describing and estimating the prescriptions and treatment patterns (125 studies, 46.8%). There was a variation in the frequency of themes according to the type of NDB data. We identified the following categories of limitations: (1) lack of information on confounders/covariates, outcomes, and other clinical content, (2) limitations regarding patients not included in the NDB, (3) misclassification of data, (4) lack of unique identifiers and register of beneficiaries, and (5) others. Although the included studies noted several limitations of using the NDB for research, they also provided some strategies to address them. Organizing the limitations of NDB in research and the related strategies across research fields can help support high-quality NDB studies.