Objective: The aim of this study was to evaluate efficacy, reasons for switching and drug survival of TNF-α inhibitors (TNFi-s) used as first and second line drugs in ankylosing spondylitis (AS).Methods: Data of patients suffering from AS and treated with at least one TNFi between November 2005 and November 2013 were extracted retrospectively from the database of one clinical center. Beside demographic data, the disease activity measured by BASDAI, the response rates (BASDAI50), reasons for switching and survival curves of TNFi-s were analyzed in general and in subgroups of patients treated with each of the available TNFi-s. The reasons for switching were defined as inefficacy, side effect of the given drug, patient's request, and occurence of extra-articular manifestations.Results: Altogether 175 patients were on TNFi and 77 of them received at least 2 TNFi-s. The patients' age at the initiation of the first TNFi was higher among switchers compared to nonswitchers (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 BASDAI was similar among non-switchers and switchers either using 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 first TNFi, the retention on therapy was unfavourable, especially in patients on infliximab after one 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 patiets treated with other agents.
Conclusion:Although the retention rate to a second line TNFi was somewhat worse than that to the first line TNFi, switching of TNFi-s is a good therapeutic option is AS patients who failed to respond to the first TNFi.