EQ-5D health utilities: exploring ways to improve upon responsiveness in psoriasis.

Aims: To determine if EuroQoL 5-Dimension Health Questionnaire (EQ-5D) health utility scores were able to discriminate among different levels of improvement in psoriasis severity following therapy.

Materials And Methods: Data were from three placebo-controlled phase 3 ixekizumab studies (UNCOVER-1, UNCOVER-2, and UNCOVER-3) with patients who had baseline Dermatology Life Quality Index scores >10 (DLQI >10). Psoriasis severity (Psoriasis Area and Severity Index [PASI]), general health utility (EQ-5D), and psoriasis-specific utility (EQ-PSO, UNCOVER-3 only) were assessed. EQ-5D-5L utility scores were generated using the England EQ-5D-5L value set, a crosswalk applied to the EQ-5D-3L United States (US) and United Kingdom (UK) value sets, and a regression-based exploratory scoring function for the EQ-PSO (UK). Analysis of variance was used to estimate change in EQ-5D-5L from baseline to Week 12 per PASI improvement level: PASI <50, PASI 50 to <75, PASI 75 to <90, PASI 90 to <100, and PASI 100. Missing data were imputed using the last observation carried forward method. Value sets for the UK, England, and the US were applied.

Results: In total, 2085 patients across UNCOVER-1, UNCOVER-2, and UNCOVER-3 had baseline DLQI >10 and available utility scores. At Week 12, mean EQ-5D utility scores increased with increasing PASI improvement levels (p < 0.001, all analyses). Mean health utilities for PASI 90 to <100 and PASI 100 were similar when based on the generic classifier, whereas a clear differentiation between PASI 90 to <100 and PASI 100 was observed for EQ-PSO mean scores (UNCOVER-3 only, n = 645; PASI 90 to <100: 0.141, PASI 100: 0.200; adjusted p = 0.043).

Limitations: EQ-5D-5L index-based scores have limited ability to differentiate among psoriasis patients at the highest PASI improvement levels. ConclusionsL Adding psoriasis-specific EQ-PSO dimensions to the EQ-5D may enhance responsiveness to improvement in skin clarity at the highest PASI levels, and, therefore, generate utility scores that better reflect treatment benefit in cost-utility models.