Development and Validation of a Quality of Life Measurement for Chronic Skin Disorders in French: VQ-Dermato

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Abstract
Background: Quality of life (QoL) assessment is crucial to assess the severity of dermatological diseases. Purpose: To construct and validate the first dermatology-specific instrument in French. Methods: Items were generated from the interview of patients. The final self-administered questionnaire, the VQ-Dermato, included 28 questions. Validity in terms of content and construct, reliability in terms of reproducibility and internal consistency, responsiveness and acceptability were tested in a population of 231 patients with 12 categories of chronic skin disorders, who were recruited and followed in hospital and private practice in France. Results: Item analysis revealed that discrimination indices were high. After factor analysis, 7 dimensions were retained, which accounted for 72% of the total variance. Cronbach’s α coefficient ranged between 0.67 and 0.88. A strong correlation was found between dimensions of the VQ-Dermato and the corresponding dimensions of the SF36. Scores were significantly different in each category of chronic skin disease and significantly higher when there was a function restriction or when the lesions were visible to others. The scale was proven to be stable by test-retest correlation. The VQ-Dermato was more responsive to clinical improvement after a 1- or 2-month treatment than the SF36. The percentage of missing responses was under 10 and the time for completing the questionnaire always under 13 min. Conclusion: The VQ-Dermato is the first valid and reliable dermatology-specific QoL instrument in French, and the first based on the concept of ‘chronic skin disorders’. It is acceptable for routine use and has a better responsiveness than a general health instrument.