Effectiveness, safety, and predictors of good clinical response in 1250 patients treated with adalimumab for active ankylosing spondylitis.

Objective: We evaluated the effectiveness and safety of adalimumab in a large cohort of patients with active ankylosing spondylitis (AS) and identified clinical predictors of good clinical response.
Methods: Patients with active AS [Bath AS Disease Activity Index (BASDAI)>or=4] received adalimumab 40 mg every other week in addition to their standard antirheumatic therapies in a multinational 12-week, open-label study. We used 3 definitions of good clinical response: 50% improvement in the BASDAI (BASDAI=50), 40% improvement in the ASsessments of SpondyloArthritis International Society criteria (ASAS40), or ASAS partial remission. Response predictors were determined by logistic regression with backward elimination (selection level 5%).
Results: Of 1250 patients, 1159 (92.7%) completed 12 weeks of adalimumab treatment. At Week 12, 57.2% of patients achieved BASDAI 50, 53.7% achieved ASAS40, and 27.7% achieved ASAS partial remission. Important predictors of good clinical response (BASDAI 50, ASAS40, and partial remission) were younger age (p<0.001), and greater C-reactive protein (CRP) concentration (p<or=0.001), HLA-B27 positivity (p<or=0.01), and tumor necrosis factor (TNF) antagonist naivety (p<0.001).
Conclusion: Adalimumab was effective in this large cohort of patients with AS, with more than half of patients achieving a BASDAI 50 or ASAS40 response and more than a quarter of patients reaching partial remission at Week 12.Younger age, greater CRP concentrations, HLA-B27 positivity, and TNF antagonist naivety were strongly associated with BASDAI 50, ASAS40, and partial remission responses. ClinicalTrials.gov identifier: NCT00478660.