Effects of medical service fee revision on reducing irrational psychotropic polypharmacy in Japan: an interrupted time-series analysis

PURPOSE: According to the revised Japanese medical service fees aimed at reducing irrational psychotropic polypharmacy, medical service fees are reduced if the number of simultaneously prescribed psychotropic drugs exceeds the standard. This study primarily aims to examine the effect of the 2018 revision. METHODS: Using a large Japanese administrative claims database, we retrospectively identified five groups (April 2013–September 2018) prescribed at least one drug from the following drug groups: anxiolytics, hypnotics, sum of anxiolytics and hypnotics, antipsychotics, and antidepressants (study population in each group: 547,511, 406,524, 759,137, 112,929, and 201,046, respectively). We used an interrupted time-series design to evaluate changes in the proportion of patients prescribed more than the standard number of drugs. RESULTS: After the 2018 revision, the proportion of patients prescribed more than the standard number of drugs significantly decreased only for the sum of anxiolytics and hypnotics; estimated changes in level and trend were − 0.60% [− 0.69%, − 0.52%] and − 0.04% [− 0.06%, − 0.02%] per month, respectively. The proportion of patients exhibiting a decrease in the number of prescribed drugs from more than the standard to within the standard increased when the revision was enforced (April 2018); this proportion in April 2018 was 36.3%, while all other proportions were in the range of 12.1–22.3%. CONCLUSION: The 2018 revision promoted a reduction in the number of prescribed drugs, which served as an important factor in the decrease in the proportion of patients prescribed more than the standard number of drugs for the sum of anxiolytics and hypnotics. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s00127-021-02147-0.