Real-life Experience with Switching TNF-α Inhibitors in Ankylosing Spondylitis

Objective: The aim of this study was to evaluate the efficacy, reasons for switching and drug survival of TNF-α inhibitors (TNFis) used as first- and second-line drugs in ankylosing spondylitis (AS).

Methods: Data on patients suffering from AS and treated with at least one TNFi between November 2005 and 2013 were extracted retrospectively from the database of a single clinical centre. Beside demographic data, the disease activity measured by the Bath Ankylosing Spondylitis Disease Activity Index (BASDAI), the response rates (BASDAI50), reasons for switching and survival curves of TNFis were analysed in general and in subgroups of patients treated with each of the available TNFis. The reasons for switching were defined as inefficacy, side effects of the given drug, patient's request and occurrence of extra-articular manifestations.

Results: Altogether, 175 patients were on TNFis and 77 of them received at least two TNFis. The patients' age at the initiation of the first TNFi was higher among switchers compared to non-switchers (42.5 ± 12.6 vs. 38.8 ± 11.2 years, p = 0.049); otherwise, gender, disease duration and initial disease activity had no influence on the risk of switching. The decrease of the BASDAI was similar among non-switchers and switchers using either the first or second TNFi, but the response rates to the first and second TNFi were worse in switchers than in non-switchers. Following the failure of the first TNFi, the retention on therapy was unfavourable, especially in patients on infliximab after 1 year of treatment. The main reason for switching from the first drug was inefficacy. The frequency of side effects that led to switching was higher in the infliximab group than in patients treated with other agents.

Conclusion: Although the retention rate to a second-line TNFi was somewhat worse than that to the first-line TNFi, the switching of TNFis is a good therapeutic option in AS patients who failed to respond to the first TNFi.