Persistence with anti-tumour necrosis factor therapies in patients with psoriatic arthritis: observational study from the British Society of Rheumatology Biologics Register

INTRODUCTION Anti-TNF therapies represent a breakthrough in the treatment of severe psoriatic arthritis. However, little is known about long-term drug persistence with these treatments in patients with psoriatic arthritis in routine clinical practice. The aim of this study was to assess persistence with first-course and second-course treatment with anti-TNF agents in a prospective cohort of psoriatic arthritis patients and to identify factors associated with and reasons for drug discontinuation. METHODS A total of 566 patients with psoriatic arthritis were registered with the British Society for Rheumatology Biologics Register (first anti-TNF agent: etanercept, n = 316; infliximab, n = 162; and adalimumab, n = 88). Treating physicians completed 6-monthly follow-up questionnaires detailing changes to anti-TNF therapies. Persistence with treatment was examined using Kaplan-Meier survival analysis. Reasons for withdrawal were classified as due to inefficacy, adverse events or other reasons. Univariate and multivariate Cox proportional hazard models were developed to examine potential predictors of withdrawals due to inefficacy or adverse events, using a range of demographic, baseline disease-specific and therapeutic variables. RESULTS At baseline, the mean (standard deviation) age of patients was 45.7 (11.1) years, 53% were female and the mean disease duration was 12.4 (8.7) years. Persistence data were available for a mean (standard deviation) follow-up of 2.3 (0.9) person-years. In total, 422 patients had completed at least 12 months of follow-up, 75.5% of whom remained on their first anti-TNF drug while 9.5% discontinued due to inefficacy, 10.0% due to adverse events and 5.0% due to other reasons. During the period of follow-up, 178 patients received a second anti-TNF therapy. The survivor function on second anti-TNF for switchers was 74% at 12 months. CONCLUSIONS Psoriatic arthritis patients show high persistence rates with both initial and second anti-TNF therapies.