Maintained clinical response of infliximab treatment in ankylosing spondylitis: a 6-year long-term study

Objectives: To investigate the efficacy, safety and drug discontinuation in patients with ankylosing spondylitis treated with infliximab, as well as the drug survival over a period of 6 years.

Methods: Forty patients with ankylosing spondylitis treated with infliximab were included in this open label study. All patients fulfilled the New York revised criteria for ankylosing spondylitis. Infliximab was given intravenously (5 mg/kg/body weight) at weeks 0, 2, 6 and every 8 weeks thereafter for a period of 6 years. Data concerning infliximab efficacy, tolerability, adverse events and drug discontinuation, were recorded. Clinical improvement according to the Bath Ankylosing Spondylitis Disease Activity Index 50% and the Ankylosing Spondylitis Assessment Study Group 20% and 40% were also recorded.

Results: A significant improvement in the Bath Ankylosing Spondylitis Disease Activity Index and Ankylosing Spondylitis Assessment Study Group scores was noted in the first year which sustained through the sixth year of treatment. More specifically, after the sixth year of treatment, Bath Ankylosing Spondylitis Disease Activity Index 50% was achieved by 65% of patients (26/40), Ankylosing Spondylitis Assessment Study Group 20% by 72.5% (29/40) and Ankylosing Spondylitis Assessment Study Group 40% was reached by 70% (28/40) of patients. Clinical improvement was associated with the reduction of acute phase reactants, such as C-reactive protein levels. After the first and the second year of treatment, the survival rate of infliximab reached 95%, after the third year it was 80%, while after the fourth year it was 72.5%, which was maintained throughout the fifth and sixth year of therapy. Five patients were increased the dose of infliximab and three of them had shortened the interval infusion. Overall, 11 patients were withdrawn during the observational period, three because of adverse events, two because of lack of efficacy, while six were lost from follow-up.

Conclusion: Infliximab was effective, safe and well-tolerated in patients with ankylosing spondylitis. The clinical response was maintained for a period of 6 years, with high infliximab survival rate, reaching the percentage of 72.5%.