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

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.

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.

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).

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.