Overall, 23 out of 30 AS patients (77%) who had participated in the initial placebo-controlled phase of the trial were included in this 2-year extension, where patients with active disease were treated with etanercept (2 × 25 mg subcutaneously twice a week). Disease-modifying anti-rheumatic drugs and steroids were not allowed. The clinical response was assessed by standard assessment tools for disease activity (Bath AS Disease Activity Index [BASDAI]), function (Bath AS Functional Index) and mobility (Bath AS Metrology Index). The primary outcome of this trial was efficacy on disease activity after 2 years of continuous treatment with etanercept in AS patients, compared with patient status at baseline (BL).