Postmarketing surveillance of safety and effectiveness of etanercept in Japanese patients with rheumatoid arthritis

Our aim was to evaluate real-world safety and effectiveness in a 6-month postmarketing surveillance study covering all Japanese patients with rheumatoid arthritis (RA) who received etanercept during a 2-year period. Data for 13,894 patients (1334 sites) enrolled between March 2005 and April 2007 were collected. Adverse events (AEs) and serious adverse events (SAEs) were reported in 4336 (31.2%) and 857 (6.2%) patients, respectively. The most frequent AEs were injection site reactions (n = 610, 4.4%) and rash (n = 339, 2.4%), whereas pneumonia (n = 116, 0.8%) and interstitial lung disease (n = 77, 0.6%) were the most frequent SAEs. Significant improvement in the proportion of patients with a good European League Against Rheumatism (EULAR) response was observed from week 4 (17.6%) to week 24 (31.6%) (p<0.001); 84.3% of patients had good or moderate EULAR responses at week 24. The percentage of patients achieving remission increased significantly from week 4 (9.3%) to week 24 (18.9%) (p<0.001). Patients with early moderate RA were less likely to experience SAEs and were more likely to achieve remission compared with patients with more severe disease. The safety and effectiveness of etanercept was demonstrated in Japanese patients in one of the largest observational trials conducted thus far in RA patients treated with biologics.