Persistent clinical efficacy and safety of infliximab in ankylosing spondylitis after 8 years-early clinical response predicts long-term outcome

Objectives. To report for the first time on the efficacy and safety of anti-TNF therapy after 8 years of follow-up in patients with active AS, and analyse possible short-term predictors for long-term clinical outcomes. Methods. In this open-label extension of a randomized controlled trial, proportions of the initially included 69 patients with active AS were treated with infliximab 5 mg/kg i.v./6 weeks for 8 years. The last report was published after 5 years. All analyses were based on completers. Results. Overall, 33 (48%) patients completed 8 years. Their mean (s.d.) BASDAI [2.6 (1.9)], BASFI [3.3 (2.6)] and BASMI [2.7 (2.4)] remained low at Year 8. At the end of Year 8, most patients were either in partial remission (n = 8, 24%) or had low disease activity (BASDAI < 3; n = 21, 64%). No new serious adverse events occurred within the past 3 years. Adverse events were the most frequent reason for dropout (56%). There were no differences between completers and dropouts at baseline, but the latter had higher BASFI values at dropout. No baseline parameter was associated with good long-term response to infliximab, but lower BASDAI levels after 12 weeks were predictive of a higher probability of partial remission [odds ratio (OR) 2.9, 95% CI 1.3, 6.3, P = 0.007], low disease activity (OR 1.7, 95% CI 1.2, 2.3, P = 0.005) or remaining on treatment (OR 0.79, 95% CI 0.61, 1.01, P = 0.06) after 8 years. Conclusion. Almost half of the initially treated patients remained on anti-TNF therapy for 8 years, and almost 90% were in partial remission or had low disease activity. Short-term response (low BASDAI at 3 months) is predictive of outcome after 8 years. Infliximab therapy was safe over 8 years.