Clinically meaningful improvement in work productivity loss in active psoriatic arthritis: post-hoc analysis of SPIRIT-P1 and SPIRIT-P2 trials

Objective. To determine the proportion of patients in Phase 3 studies (SPIRIT-P1 and SPIRIT-P2) who achieved minimal clinically important difference (MCID) for work productivity loss and activity impairment domains of Work Productivity and Activity Impairment Specific Health Problem (WPAI-SHP) questionnaire. Methods. In the SPIRIT-P1 study, comprising a 24-week double-blind treatment period, biologic-naive patients with active psoriatic arthritis (PsA) were randomised to irekizumab 80 mg every 4 weeks (IXEQ4W) or every 2 weeks (IXEQ2W) (starting dose of 160 mg), adalimumab 40 mg every 2 weeks (ADAQ2W), or placebo. SPIRIT-P2 enrolled tumour necrosis factor inhibitor (TNFi)-experienced patients who were randomised to receive IXEQ4W, DCEQ2W or placebo for 24 weeks of double-blind treatment. In this post-hoc analysis, we investigated the proportion of patients in SPIRIT-P1 and P2 studies who achieved 15% improvement in work productivity loss and 20% improvement in activity impairment domains of WPAI-SHP during double-blind treatment period. Results. In SPIRIT-P1, at Week 24, 57.1% and 55.8% of biologic-naive patients on IXEQ4W and ADAQ2W respectively, achieved MCID estimates for work productivity loss compared to 25.6% of patients treated with placebo. The proportion of ixekizumab- and adalimumab-treated patients achieving MCIDs for activity impairment were significantly higher (IXEQ4W: p<0.001; ADAQ2W: p=0.001) compared to placebo-treated patients at Week 24. In SPIRIT-P2, significantly more TNFi-experienced patients on IXEQ4W (p<0.001) achieved MCIDs compared to placebo at Week 24. Conclusion. Treatment with ixekizumab was associated with clinically meaningful improvements in WPAI-SHP domains in biologic-naive and TNFi-experienced patients with active PsA.