OBJECTIVES: To assess the effectiveness and tolerability of first- and second-line interleukin (IL)-17A inhibitor treatment in patients with psoriatic arthritis (PsA) from 2014 to 2021, using data from the Danish Rheumatology Registry (DANBIO) by investigating adherence to therapy.

METHOD: PsA patients recorded in DANBIO who received a first- or second-line IL-17A inhibitor treatment were included in this study. All patients included had previously received ≥1 TNFi treatment. Baseline characteristics were analyzed in subgroups: first-line IL-17A inhibitor treatment and second-line IL-17A inhibitor treatment. adherence to therapy of first- or second-line IL-17A inhibitor treatments were reported as Kaplan-Meier plots.

RESULTS: 534 patients were included in the study; first-line switchers: 534 (secukinumab: 510, ixekizumab: 24), second-line switchers: 102 (secukinumab: 35, ixekizumab: 67). Baseline characteristics showed a similar Health Assessment questionnaire (HAQ) and Visual Analogue Scale (VAS) pain. VAS global, Disease Assessment Score-28CRP and previous number of bDMARD treatments are similar with a greater value for second-line switchers. First-line ixekizumab treated patients present a younger age, greater percentage of females, a lower disease duration and a lower CRP value. Concomitant MTX use was greater for the first-line secukinumab treated patients. First- and second-line switchers had a similar adherence to therapy. Second-line secukinumab and second-line ixekizumab switchers showed a similar adherence to treatment.

CONCLUSION: PsA patients receiving first- or second-line IL-17A inhibitors showed homogeneous baseline characteristics and similar adherence to therapy. Treatment failure of the first IL-17A inhibitor treatment should not preclude a second-line IL-17A inhibitor treatment.