Implementation Status of Liver Function Tests for Monitoring Benzbromarone-Induced Hepatotoxicity: An Epidemiological Survey Using the Japanese Claims Database

A major adverse effect of benzbromarone is hepatotoxicity. Therefore, periodic liver function tests are required at least for the first 6 months of benzbromarone administration. However, it is not clear whether the relevant blood tests are implemented appropriately. Here, we performed a cross-sectional survey of the implementation status of liver function tests in patients who were newly prescribed benzbromarone, using the Japanese large claims database. Male patients who were newly prescribed benzbromarone from January 2010 to December 2016 were included. We targeted patients who continued benzbromarone during the observation period (up to 180d from the start of administration). The primary endpoint was the proportion of patients in whom periodic liver function tests were implemented. A periodic liver function test was defined as one or more liver function tests performed during both 1-90 and 91-180d of initial benzbromarone administration. We labeled the tests as a "periodic test" or "non-periodic test" based on whether periodic liver function tests were performed or not, respectively. Furthermore, factors influencing non-periodic test were analyzed. Periodic testing was implemented only in 28.7% of patients. Additionally, factors such as number of hospital beds <19 (compared to 100-199 beds) and duration of the first prescription of benzbromarone were associated with non-periodic testing. Our study revealed that periodic liver function tests are not performed sufficiently in Japan. Thus, clinicians prescribing benzbromarone should be educated about the test. Our blood-test-based approach should be applied to other drugs and countries in future research.