Switching between tumour necrosis factor blockers in spondyloarthritis: a retrospective monocentre study of 222 patients.

Objectives: To assess the frequency and effectiveness of switching TNF blockers in spondyloarthritis, and the predisposing factors of this effectiveness.
Methods: This was a retrospective systematic monocentre study; inclusion criteria were definite spondyloarthritis (Amor's criteria) and introduction of a first TNF blocker after January 2004. The retention rate of the first and second TNF blocker (if applicable) was evaluated (Kaplan-Meier technique). Patients' characteristics were compared with regard to requirement for switching. Predisposing factors of retention of the second TNF blocker were analysed (log-rank, Cox).
Results: A total of 222 patients started a first TNF blocker; 79% fulfilled the New York modified criteria, with increased CRP (75%) and median BASDAI of 50 (35-61). Mean follow up was 29±20 months (i.e. a total of 538 patient-years). By the end of follow-up, 72 patients (32%) had switched to a second TNF blocker. Patients who switched had more peripheral enthesitic symptoms (p=0.01) and a tendency for more peripheral involvement (p=0.06). Retention of the first and second TNF blocker was similar (p=0.32). No predictive factors were found for retention of the second TNF blocker; including no difference between TNF blockers and between reasons for stopping the first.
Conclusions: The effectiveness of switching TNF blocker in spondyloarthritis appears clinically relevant; no predictive factors of this effectiveness were evidenced.