Search of official nationwide database in Japan for adverse events associated with disease-modifying antirheumatic drug therapies: focus on therapies in combination with methotrexate.

BACKGROUND: Disease-modifying antirheumatic drugs (DMARDs) are essential for rheumatoid arthritis (RA) therapy. The adverse events (AEs) evaluation should focus on that methotrexate (MTX) is frequently prescribed in combination with others (combination MTX). METHODS: A search of the website of the official Japanese Agency for AEs, including lymphoproliferative disease (LPD), cytopenia, interstitial pneumonia, infectious pneumonia other than Pneumocystis jirovecii pneumonia (PCP) (i-Pn), and PCP, associated with MTX, tacrolimus, adalimumab, tocilizumab, and abatacept therapies reported from 2014 to 2016 was performed. Number of each AE cases and its ratio to total number of AEs cases were examined. Combination MTX was checked for RA cases. RESULTS: A total of 8874 cases were listed. In 3955 MTX cases, LPD was most frequent (36.4%). In any of the other four DMARDs cases, i-Pn was most frequent (4.2 ~ 15.3%); PCP cases showed most frequent combination MTX (94.4%). In total, including cases reported for MTX therapy, 98.2% of LPD and 97.6% of PCP cases had MTX, and less than 90% of the other AEs cases had MTX. CONCLUSION: LPD was by far the most frequent AE associated with MTX therapy. PCP was strongly associated with combination MTX. For any of the other four DMARDs, i-Pn was most frequent.