Validation of the Spanish Acne Severity Scale (Escala de Gravedad del Acne Espanola - EGAE)

Background: Several acne grading systems have been described, but consensus is lacking on which shows superiority. A standardized system would facilitate therapeutic decisions and the analysis of clinical trial data. Objective: To assess the feasibility, reliability, validity and sensitivity to change of the Spanish Acne Severity Scale (EGAE). Materials & Methods: A Spanish, multicentre, prospective, observational study was performed in patients with facial, back or chest acne assessed using EGAE, Leeds Revised Acne Grading system (LRAG) and lesion count. Clinicians answered 4 questions regarding EGAE use and time employed. Patients were evaluated at baseline and after 5 1 weeks. Four additional blinded observers, all dermatologists, evaluated patients' pictures using EGAE and LRAG. Results: In total, 349 acne locations were assessed in 328 patients. Of the dermatologists, 95.6% (CI: 92.9-97.5%) reported that EGAE was easy to use, and 75% used it in <= 3 minutes. Interobserver reliability of the EGAE scale was shown by a Kendall's W of 0.773 (p<0.001). EGAE and LRAG scales showed a high correlation (Spearman's correlation >0.85; p<0.001). EGAE mean score in treatment-compliant patients was significantly lower at follow-up than at baseline (2.14 vs. 1.57, p<0.001, Cohen's d = 0.35).The pre-post-treatment difference in EGAE mean score in non-compliant patients was not significant (1.44 vs. 1.32, p<0.102) and Cohen's d was lower (0.19) than in compliant patients. Conclusion: The use of EGAE to evaluate acne grade in daily clinical dermatological practice in Spanish centres has shown feasibility, high interobserver reliability, concurrent validity and sensitivity to detect treatment effects.