This study aims to explore the measurement agreement between direct and indirect health
utility measures in four chronic dermatological conditions (atopic dermatitis, hidradenitis
suppurativa, pemphigus, psoriasis). Outpatients survey data collected between 2015
and 2021 were analysed. Health-related quality of life (HRQoL) outcome measures included
time trade-off (TTO), EQ-5D-5L and Dermatology Life Quality Index (DLQI). Descriptive
statistics were computed for the pooled sample and four diseases. Mean, standard deviation
(SD), median, interquartile range (IQR), ceiling and floor effects were calculated
for TTO, EQ-5D-5L and DLQI utilities. Bland‒Altman plots and intraclass correlation
coefficients (ICC) were applied to investigate the agreement between health utility
measures. Sociodemographic characteristics (age, sex, educational level, employment
status) and health-related information (disease duration, outpatient care visits in
the past 3 months and disease severity) impact on utilities was investigated by Tobit
regressions. The sample includes N = 765 patient responses with a mean age of 41.5
(SD = 16.2), majority being males (52.7%). Total sample mean utilities were the highest
according to TTO (0.83), followed by EQ-5D-5L and vDLQI (0.81 and 0.81) and lowest
in mDLQI (0.77). Measurement agreement was found only between TTO and EQ-5D-5L. Skin-disease
severity impacted all health state utilities, though only TTO differentiated utility
values according to disease type. The discrepancies between the TTO and DLQI warn
to compare DLQI-based utilities in different dermatological conditions with extreme
caution.
