Measuring Quality of Life in Hidradenitis Suppurativa: Development and Validation of a Disease-specific Patient-reported Outcome Measure for Practice and Research.

Hidradenitis suppurativa is a chronic disease that disrupts patients' physical and psychological well-being. A disease-specific measure was developed and validated for assessing health-related quality of life in hidradenitis suppurativa. After qualitative item development, the quality of life in hidradenitis suppurativa instrument was tested in 101 patients, applying convergent measures and a usability questionnaire. Descriptive and validation-specific analyses were conducted. There was no ceiling, but moderate floor effects (scores between 0 and 3.13 on a scale of 0-4). Few missing values were observed (21 of 23 items < 5%). Internal consistency was satisfying: 2 subscales with 6 and 16 items were identified (Cronbach's alpha=0.95 and 0.88). The quality of life in hidradenitis suppurativa instrument correlated significantly with all convergent criteria (including change in convergent patient-reported outcomes; p < 0.05) except for Hurley stage (p = 0.490). In conclusion, the quality of life in hidradenitis suppurativa questionnaire is an internally consistent, valid, responsive, and usable instrument to assess quality of life in patients with hidradenitis suppurativa.