Supplementary Material for: International validation of the Quality of Life Relevance-Acne questionnaire

Introduction. An acne-specific questionnaire Quality of Life Relevance-Acne (QOLRELEVANCE-ACNE), was developed to evaluate Health-related Quality of Life based on the most relevant topics for acne patients. The aim of the present study was to undertake an international validation of the QOLRELEVANCE-ACNE questionnaire and to propose a severity grading system for its scores.
Methods. Patients with acne were asked to fill in the QOLRELEVANCE-ACNE and Dermatology Life Quality Index (DLQI) questionnaires. Global acne severity was assessed independently by both dermatologists and patients. Cronbach’s alpha was used for assessment of internal consistency of the QOLRELEVANCE-ACNE questionnaire. Spearman rank correlation was used to study convergent validity and test-retest reliability of the QOLRELEVANCE-ACNE questionnaire. DLQI severity banding system and global acne severity grades were applied to develop variants of the scoring system for the QOLRELEVANCE-ACNE questionnaire.
Results. The results of 726 patients with acne across seven countries (Bulgaria, Ukraine, Greece, Spain, Sri Lanka, Croatia, and Malta) were analysed. Cronbach’s alpha was 0.94 for the entire QOLRELEVANCE-ACNE questionnaire, 0.90 for the Socioemotional, 0.88 for the Symptoms, and 0.76 for the Stigma and Suicidal thoughts’ domains. The QOLRELEVANCE-ACNE questionnaire showed high test-retest reliability (r=0.96, p<0.001) and strong correlation with DLQI scores (r>0.6, p<0.001 in all countries). The following grading system of the QOLRELEVANCE-ACNE questionnaire scores was accepted: total scores <20 indicate a mild effect, scores from 20 to 30 indicate a moderate effect and scores >30 indicate a severe effect on a patient's life.
Conclusion. Simultaneous international validation of the QOLRELEVANCE-ACNE questionnaire confirmed its convergent validity, internal consistency and test-retest reliability. A grading system of the QOLRELEVANCE-ACNE questionnaire scores was accepted.