The primary objective of the study was to compare the efficacy of etanercept (25 mg, twice weekly) with that of placebo based on the percentage of patients who achieve the Assessment in Ankylosing Spondylitis (ASAS) response criteria (ASAS 20%) at week 12.

Main inclusion criteria

• Diagnosis of AS (defined by Modified New York Criteria for Ankylosing Spondylitis).
• Active AS (defined by the average of scores on the visual analog scale [VAS] of ≥ 30 for duration and intensity of morning stiffness and by 2 of the following: VAS for patient global assessment ≥ 30; average of VAS for nocturnal and total pain ≥ 30; BASFI ≥ 30 (all scores on a scale of 0 to 100).
• 18 to 70 years of age.

Main exclusion criteria

• Complete ankylosis (fusion) of spine.
• Previous receipt of etanercept, antibody to tumour necrosis factor alpha (TNFα), or other TNFα inhibitors.
• Use of disease-modifying antirheumatic drugs (DMARDs) other than hydroxychloroquine, sulphasalazine, or methotrexate within 4 weeks of baseline.