Early Treatment Targets for Predicting Long-term Dermatology Life Quality Index Response in Patients with Moderate-to-Severe Plaque Psoriasis: A Post-hoc Analysis from a Long-term Clinical Study

Abstract

BACKGROUND: Rapid improvements in health-related quality of life (HRQoL) and psoriasis severity have been reported in patients treated with ixekizumab (IXE), an interleukin (IL)-17A antibody. OBJECTIVE: We assessed the relationship between early Psoriasis Area and Severity Index (PASI) response and long-term Dermatology Life Quality Index (DLQI) improvement in patients in the randomized clinical trial IXORA-S (NCT0256186) treated with IXE or IL-12/23 (ustekinumab [UST]). METHODS: The proportion of patients achieving DLQI (0,1), an outcome equivalent to the patient's skin condition having no impact on HRQoL after 52 weeks of IXE or UST by PASI response at Weeks 4, 12, and 24 was quantified. Optimal thresholds for PASI response by treatment to predict Week 52 DLQI (0,1) were calculated based on Youden's Index. RESULTS: Early and higher levels of skin clearance were associated with improved patient outcomes regardless of treatment. Patients treated with IXE achieved faster and more pronounced PASI response than patients treated with UST. The optimal thresholds at Weeks 4, 12, and 24 for predicting DLQI (0,1) at Week 52 were ~PASI 75 for IXE versus ~PASI 50 for UST at Week 4, PASI 90 for IXE versus PASI 75 for UST at Week 12, and ~PASI 100 for IXE versus ~PASI 90 for UST at Week 24. Among patients achieving these thresholds, the probability of achieving a DLQI (0,1) was significantly higher. CONCLUSION: Earlier and higher levels of skin clearance are associated with improved patient outcomes over the long term, regardless of treatment.

Keywords: Dermatology Life Quality Index; Psoriasis Area and Severity Index; ixekizumab; psoriasis.