Effect of filgotinib on health-related quality of life in active psoriatic arthritis: a randomized phase 2 trial (EQUATOR)

To examine the effects of filgotinib, an oral, selective Janus kinase 1 inhibitor, on health-related quality of life (HRQoL) using the Psoriatic Arthritis Impact of Disease (PsAID)9 questionnaire in active PsA. Methods: Patients were randomized 1: 1 to filgotinib 200 mg or placebo once daily for 16 weeks in EQUATOR, a multicentre, double-blind, phase 2 randomized controlled trial. HRQoL was assessed with PsAID9 at Weeks 4 and 16. Change from baseline in total and individual domain scores, plus the proportions of patients achieving minimal clinically important improvement (MCII; ≥3 points) and patient-accepted symptom status (PASS; score <4), were evaluated. Correlation with the 36-item short-form health survey (SF-36) was investigated. Results: One hundred and thirty-one patients were randomized to filgotinib or placebo. Filgotinib effects on PsAID9 were observed from Week 4. At Week 16, mean (s.d.) change from baseline in PsAID9 was -2.3 (1.8) and -0.8 (2.2) for filgotinib and placebo, respectively (least-squares mean of group difference -1.48 [95% CI -2.12, -0.84], P < 0.0001), with significant improvements in all domains vs placebo. Significantly more patients on filgotinib achieved MCII (group difference 25.4% [95% CI 8.92, 39.99], P = 0.0022) and PASS (group difference 29.6% [95% CI 10.65, 45.60], P = 0.0018) at Week 16 vs placebo. Similar improvements in SF-36 were observed, with moderate to strong negative correlation between PsAID9 and SF-36. Conclusion: Filgotinib significantly improved HRQoL vs placebo in patients with active PsA, as measured by PsAID9. To our knowledge, EQUATOR is the first randomized controlled trial to evaluate PsAID9. Trial registration: ClinicalTrials.gov, https://clinicaltrials.gov/ct2/show, NCT03101670.