Abstract
Disease-modifying antirheumatic drugs (DMARDs) are essential for rheumatoid arthritis (RA) therapy, and many synthetic and biologic drugs are available. DMARDs are frequently prescribed in combination with methotrexate (MTX), as it is the first-line drug. The adverse events (AEs) associated with DMARDs have sometimes unfavorable outcomes. Major AEs, particularly therapies in combination with methotrexate, were investigated in this study. A search of the website of the Japanese Pharmaceuticals and Medical Devices Agency for AEs associated with therapies with five DMARDs (MTX, tacrolimus, adalimumab, tocilizumab, and abatacept) reported from 2014 to 2016 was performed. The AEs searched included lymphoproliferative disease (LPD), cytopenia, interstitial pneumonia (IP), infectious pneumonia other than Pneumocystis jirovecii pneumonia (PCP) (i-Pn), and PCP. The number of cases of each AE and its ratio to the total number of cases of all AEs associated with each DMARD therapy were examined. Data were compared among AEs and DMARDs. MTX therapy in combination with other DMARDs was examined for rheumatoid arthritis (RA) cases. On the website, a total of 8874 cases were listed as having AEs associated with therapies with the five DMARDs. For MTX therapy, LPD was the most frequent (1438 cases, 36.4% of all AE cases), followed by cytopenia (10.9%), IP (6.2%), i-Pn (4.1%), and PCP (2.6%). Under therapy with any of the other four DMARDs, i-Pn showed the largest number of cases and the highest ratio (4.2–15.3%); other AEs varied in number and ratio. The proportion of use of MTX in combination with the four DMARDs was highest for PCP (67/71, 94.4%), followed by LPD (50/73, 68.5%), cytopenia (48/73, 65.8%), i-Pn (101/173, 58.4%,), and IP (36/80, 45.0%) (Table 1). In total, including cases reported for MTX therapy, 98.2% (1286/1309) of LPD cases, 88.5% (193/218) of cytopenia cases, 79.8% (174/218) of IP cases, 76.4% (233/305) of i-Pn cases, and 97.6% (165/169) of PCP cases had MTX. In conclusion, LPD was by far the most frequent AE associated with MTX therapy. PCP was strongly associated with the use of MTX in combination with another DMARD. For therapy with any of the other four DMARDs, i-Pn showed the highest ratio.