Clinical response, drug survival, and predictors thereof among 548 patients with psoriatic arthritis who switched tumor necrosis factor α inhibitor therapy: results from the Danish Nationwide DANBIO Registry

Objective: To describe the frequency of treatment switching and outcomes among patients with psoriatic arthritis (PsA) who switched tumor necrosis factor α inhibitor (TNFi) agents in routine care.

Methods: We conducted an observational cohort study based on the Danish nationwide DANBIO registry. Treatment outcomes were evaluated using the American College of Rheumatology criteria for 20% improvement (ACR20)/ACR50/ACR70, European League Against Rheumatism (EULAR) response criteria for good response, and the 28-joint count Disease Activity Score (DAS28) (remission). Kaplan-Meier and regression analyses were used for drug survival analyses and to identify predictors of outcome after treatment switching.

Results: Of 1,422 patients starting TNFi agents, 548 patients (39%) switched to a second biologic drug during up to 10 years of followup. Median followup was 2.3 years (interquartile range [IQR] 1.0-4.3 years). Switchers were more frequently women (56% versus 45%), had a shorter disease duration (3 versus 4 years), a higher median Health Assessment Questionnaire (HAQ) score (1.1 [IQR 0.6-1.6] versus 0.9 [IQR 0.5-1.4]), DAS28 (4.8 [4.0-5.7] versus 4.4 [3.6-5.2]), pain score on a visual analog scale (VAS) (65 mm [46-77] versus 62 mm [40-75]), and fatigue score on a VAS (69 mm [50-83] versus 64 mm [42-80] mm) (all P < 0.05 at start of first TNFi). During the first and second treatment, HAQ, DAS28, and VAS scores and C-reactive protein levels had decreased after 6 months (all P < 0.05), and median drug survival was 2.2 versus 1.3 years (P < 0.001). Lower fatigue score increased survival of the second TNFi. After switching, the proportions of patients achieving a sustained ACR20, ACR50, ACR70, EULAR good response, and DAS28 remission after 3-6 months were 22% (number needed to treat [NNT] 4.5), 13% (NNT 7.9), 5% (NNT 20), 19% (NNT 5.3), and 34% (NNT 2.9), respectively. Response rates were lower during the second treatment (all P < 0.01 versus first TNFi). At the 2-year visit, 47% of switchers had achieved an ACR20 response. No differences between drug-drug combinations were found.

Conclusion: Thirty-nine percent of the patients with PsA switched TNFi agents. Response rates and drug survival were lower after switching; however, half of the switchers had an ACR20 response 2 years after starting the first TNFi.