Long-term persistence of TNF-inhibitor treatment in patients with psoriatic arthritis. Data from the British Society for Rheumatology Biologics Register.

Background: Long-term effectiveness of tumour necrosis factor alpha inhibitors (TNFi) has mainly been explored in patients with rheumatoid arthritis (RA) and the data available on patients with psoriatic arthritis (PsA) includes limited follow-up.

Objective: Investigate long-term effectiveness of first TNFi in a PsA population by describing treatment persistence, identify factors associated with 5-year persistence and further investigate comparative long-term effectiveness of subsequent TNFi treatments through persistence to treatment.

Methods: Patients with a rheumatologist diagnosis of PsA receiving their first TNFi registered in the British Society for Rheumatology Biologics Register (BSRBR) (2002-2006) were included. Treatment at different time points was described and factors associated with 5-year treatment persistence were identified by logistic regression. Kaplan-Meier analysis was used to assess factors associated with persistence to first TNFi and subsequent TNFi treatments.

Results: At 5 years, 46.7% of patients were still on their initial TNFi treatment. Better 5 -year persistence was associated with male gender, use of etanercept or adalimumab rather than infliximab and absence of baseline comorbidity. Five-year persistence estimates (95% CI) of first, second and third TNFi were 53% (49% to 57%), 60% (43% to 57%) and 48% (36% to 59%), respectively.

Conclusion: We found good long-term persistence of TNFi in this PsA population both for the first and subsequent TNFi treatments. The relationship between persistence and relevant clinical factors was not strong and demonstrates the difficulties in predicting outcome of TNFi treatment in PsA.