Treatment response, drug survival, and predictors thereof in 764 patients with psoriatic arthritis treated with anti-tumor necrosis factor α therapy: results from the nationwide Danish DANBIO registry

Objective: To investigate disease activity, treatment response, and drug survival, and predictors thereof, among Danish patients with psoriatic arthritis (PsA) receiving their first treatment series with a tumor necrosis factor α (TNFα) inhibitor.

Methods: Patients with PsA were identified from a prospective nationwide rheumatologic database, the Danish biologics registry DANBIO, using data registered from 2000-2009. Information was obtained on the patients' clinical response to anti-TNFα treatment (defined as achievement of the American College of Rheumatology 20% [ACR20], ACR50, and ACR70 improvement criteria or a European League Against Rheumatism [EULAR] good response at least once during the first 6 months of treatment) and duration and rate of drug adherence (referred to as drug survival), as well as predictors thereof.

Results: Of 764 patients with PsA, 320 received adalimumab, 260 infliximab, and 184 etanercept. Median drug survival was 2.9 years, and 1-year and 2-year drug survival rates were 70% and 57%, respectively. Clinical parameters that showed improvement over 6 months were the C-reactive protein (CRP) level, Health Assessment Questionnaire score, and 28-joint Disease Activity Score. Male sex, CRP level >10 mg/liter, concomitant methotrexate use, and low patient health visual analog scale score at baseline were associated with longer drug survival. Improvement was achieved by 59%, 45%, 24%, and 54% of patients according to the ACR20, ACR50, ACR70 response criteria and EULAR good response, respectively. A CRP level >10 mg/liter was predictive of the improvement responses (odds ratio [OR] 2.6 for ACR20, OR 3.0 for ACR50, OR 3.6 for ACR70, and OR 2.2 for EULAR good response).

Conclusion: In these patients with PsA treated with their first TNFα inhibitor in clinical practice, high drug adherence and responder rates were observed. Moreover, increased levels of CRP at baseline were associated with both good treatment responses and continued treatment, which may be of clinical value in selecting the patients most likely to benefit from treatment with TNFα inhibitors.