Health Utility and Validity of the EQ-5D-5L in Thai Patients With Pemphigus and Bullous Pemphigoid

To estimate health utility using the EuroQol 5-Dimension 5-Level instrument (EQ-5D-5L) and to evaluate its validity, including convergent and known-group validity, in patients with pemphigus and bullous pemphigoid.

A cross-sectional study was conducted among adults with pemphigus or bullous pemphigoid receiving outpatient or inpatient care at the Institute of Dermatology, Thailand. Participants completed the EQ-5D-5L and the Dermatology Life Quality Index (DLQI). Convergent validity was assessed using Spearman's correlations between EQ-5D-5L utility, EQ visual analog scale (EQ-VAS), and DLQI scores, whereas known-group validity was examined by comparing EQ-5D-5L utility scores across demographic and clinical subgroups.

A total of 178 patients were included. The median EQ-5D-5L utility score was 0.94 (interquartile range [IQR] 0.84-1.00), and the mean was 0.86 ± 0.23. The mean EQ-VAS score was 73.42 ± 14.99. The most frequently affected dimensions were pain/discomfort (34.3%), mobility (32.0%), and anxiety/depression (27.0%). EQ-5D-5L utility and EQ-VAS scores were significantly correlated with DLQI (ρ = -0.413 and -0.282; P < .001) and with each other (ρ = 0.446; P < .001), supporting convergent validity of the EQ-5D-5L. Significant differences across subgroups defined by age, education level, number of comorbidities, disease severity, current disease status, and disease duration (P < .05) further supported known-group validity.

The EQ-5D-5L demonstrated satisfactory validity and effectively captured both general and dermatology-specific aspects of health among patients with pemphigus and bullous pemphigoid. The health utility values generated in this study provide essential inputs for health technology assessment and economic evaluation in Thailand, supporting more equitable access to effective treatments.