Safety and effectiveness responses to etanercept for rheumatoid arthritis in Japan: a sub-analysis of a post-marketing surveillance study focusing on the duration of rheumatoid arthritis

The aim is to investigate the relationship of duration of rheumatoid arthritis (RA) with safety and effectiveness of etanercept (ETN) in Japan. Post-marketing surveillance data for 7,099 patients treated with ETN were analyzed. Baseline characteristics, treatment effectiveness, incidence of adverse events (AEs), and serious AEs (SAEs) in relation to duration of RA were studied. At baseline, patients with RA for longer duration were older, weighed less, had more comorbidities, allergies, and corticosteroid use, but smoked less and had less morning stiffness. By 2–5 years with RA, more than half of the patients had advanced to Steinbrocker radiographic stage III or IV. Methotrexate (MTX) was the most commonly used pre-treatment disease-modifying antirheumatic drug; however, concomitant MTX use and its dose were lower among patients with longer duration of RA. Remission rates (26.6%) were greatest among patients having RA for <2 years. Less AEs and SAEs were observed among patients with shorter duration of RA. These results suggest that RA treatment in Japan in the era pre-biologics may not have been adequate to control disease activity and prevent joint destruction. Patients with shorter duration of RA may have better physical status which allows the opportunity to treat more intensively putting a higher percentage of patients in remission and possibly decreasing exposure to SAEs.