The comparative effectiveness of tumor necrosis factor-blocking agents in patients with rheumatoid arthritis and patients with ankylosing spondylitis: a six-month, longitudinal, observational, multicenter study

OBJECTIVE: To compare the effectiveness of tumor necrosis factor (TNF)-blocking agents (etanercept and infliximab) in patients with rheumatoid arthritis (RA) and patients with ankylosing spondylitis (AS). METHODS: Data from an ongoing longitudinal, observational study in Norway were used to assess changes in health-related quality of life (HRQOL) in patients with RA (n = 291) and AS (n = 62). Patients received anti-TNF therapy, and changes in scores on the Short Form 36 (SF-36), SF-6D, modified Health Assessment Questionnaire, and visual analog scales for patients' assessments of pain, fatigue, and global status from baseline to followup examinations at 3 and 6 months were compared. Data were adjusted for age, sex, and baseline values and are presented as crude estimates as well as standardized response means. RESULTS: Both groups had improvements in all measures at 3 and 6 months. At 3 months, the changes were significantly better in the AS group compared with the RA group for all measures except the SF-36 social functioning scores. At 6 months, all changes were numerically greater in the AS group. Differences were significant for the SF-36 role emotional scores and were borderline significant for the SF-36 physical functioning, role physical, and vitality scores and for the SF-6D scores. CONCLUSION: In this real-life setting, patients with AS experienced improvement in HRQOL that was comparable to, and sometimes greater than, that observed in RA patients. These results support the idea that patients with AS should have the same access to TNF-blocking agents as patients with RA.