OBJECTIVES: We aim to compare the measurement properties of three indirect (EQ-5D-5L, Patient-Reported Outcomes Measurement Information System-Preference [PROPr] based on PROMIS-29+2 and Short-form 6-dimensions [SF-6Dv1] based on SF-36) and one direct (conventional 10-year time trade-off [TTO]) utility assessment methods in patients with chronic skin diseases.

METHODS: In November 2020, 120 patients with physician-diagnosed chronic skin diseases (mean age 49 years, female 61%) completed an online cross-sectional survey in Hungary. US value sets were used for the EQ-5D-5L and PROPr, and the UK one for the SF-6D. Floor, ceiling, convergent and known-group validity were compared across the four utility measures. Known-groups were created based on the first item of SF-36 and the first four items of PROMIS Global Health (general health, quality of life, physical and mental health). The agreement between utilities was analysed using Bland-Altman plots.

RESULTS: Mean ± SD utilities of the EQ-5D-5L, PROPr and SF-6D were 0.79±0.24, 0.47±0.24 and 0.71±0.15, while 0.89±0.23 for the TTO. The ceiling was 65% for the TTO, 27% for the EQ-5D-5L, 2% for the SF-6D and 0% for the PROPr. Indirectly assessed utilities showed strong correlations with each other (range of r_s=0.771 to 0.987), while the TTO exhibited weak correlations with indirect utilities (range of r_s=0.171 to 0.193). The EQ-5D-5L was able to better discriminate between known groups of patients defined based on general health, quality of life and physical health, while the SF-6D and PROPr outperformed the EQ-5D-5L for mental health problems. The Bland-Altman plots confirmed the good agreement between indirect utilities.

CONCLUSIONS: Utilities measured by different instruments showed a great variability in patients with chronic skin conditions. All indirect methods exhibited generally good measurement properties. Our findings help to understand the differences across these measures and support the choice of instrument for quality-adjusted life year calculations in cost-utility analyses.