Evaluation of the Responsiveness of Investigator Global Assessment Score (KP-IGA) and Composite Area Index (KPAI) for Keratosis Pilaris
Description
Background: Keratosis Pilaris (KP) is a benign skin disorder that appears as perifollicular papules on the extensor aspects of the limbs, face, and buttocks. A standardized severity outcome measure is important for the assessment of dermatological conditions. Therefore, the Keratosis Pilaris Investigator Global Assessment (KP-IGA) and its composite area index (KPAI) were developed. Objectives: To establish the responsiveness and Minimal Clinically Important Differences (MCIDs) for both KP-IGA and KPAI. Methodology: This prospective pilot study involves 16 patients enrolled for 3 whole-body laser treatment sessions at 4-weekly intervals. Prior to each laser treatment, patients were evaluated by the same 2 assessors using the KP-IGA, KPAI, Physician Global Assessment (PGA), and a Likert Scale of the magnitude of change. The patients then attend a 4th visit for the final scoring session. The data collected was used to determine the responsiveness of the KP-IGA and KPAI. To allow a better understanding of the severity and subjective impact of the condition, the patients also completed the Dermatology Quality of Life (DLQI) questionnaire during each visit. Results: KPAI was shown to be more responsive than KP-IGA to changes in KP skin conditions, achieving a higher correlation with PGA than KP-IGA (R2 = 0.725; R2 = 0.681). The MCID scores for KP-IGA and KPA are 1 and 5, respectively. KPAI disease severity cut-offs for moderate and mild are 10 and 34. Conclusion: To complete the validation for this first KP-specific scoring system, this study has demonstrated the remarkable responsiveness of both KP-IGA and KPAI. Therefore, this scoring tool is proven to be readily applicable for clinical trials of new treatments for KP. *The licenses of KP-IGA and KPAI are owned by the Autoimmune Blistering Disease Foundation (ABDF).