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?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.