Use of a novel quantitative tool for evaluation of pseudo-acanthosis nigricans: acanthosis nigricans area and severity index (ANASI)

Abstract

Background Pseudo-acanthosis nigricans (pseudo-AN) is a common clinical scenario, which can be challenging to treat. Evaluating the efficacy of different therapeutic conditions requires a clinical outcome measure. Objective To compare the novel score acanthosis nigricans area and severity index (ANASI) with a conventional severity scale. Patients and methods A total of 20 patients with neck pseudo-AN were enrolled in the study. Each side of the neck was randomly subjected to receiving biweekly three sessions of either glycolic acid peel 70% or saline (serving as a control). Evaluation was done at baseline and 1 week after the last session by ANASI score versus a simple categorical 0–4 severity scale. For evaluating interrater and intrarater reliability and validity, six raters were asked to evaluate each side of the neck before and after treatment by both the ANASI and severity scale. Results Glycolic acid caused a 43% and a 13% improvement according to the ANASI scoring system and the severity scale, respectively, with a highly statistical significance between both. ANASI score showed good reliability across and between raters and was considered valid when compared with the severity scale. Conclusion ANASI is an easy-to-apply and reproducible scoring system that lessens the bias in subjective evaluation; thus, it offers accurate quantification of pseudo-AN. ANASI score is a reliable and valid measure for AN skin lesions.

Keywords

• acanthosis nigricans area and severity index
• glycolic acid
• outcome measure
• pseudo-acanthosis nigricans
• reliability
• validity