Picture-based acne lesion counts: A validation study to assess accuracy and reliability of acne lesion counts via photography.

ABSTRACT

BACKGROUND: Acne lesion counting (ALC) is widely used to evaluate efficacy of new acne treatments. Although such evaluations are precise and highly discriminative, if assessed live, it can be a time-consuming and intrusive measurement. Photographic assessment is a viable mode for ALCs and for training and/or qualifying evaluators. AIMS: The purpose of this study was to validate photographic methods for performing ALCs and to provide an objective measurement tool to train and/or qualify lesion count evaluators for deployment in both small- and large-scale studies. PATIENTS/METHODS: Assess accuracy and reliability of acne lesion counting via photographic methods in 8 subjects aged 16 to 40 years, with Fitzpatrick Skin Types I to VI. Frontal and 45°angle images taken at the single in-clinic visit. Each subject underwent 3 counts per 4 evaluators 1 set of live counts and 2 sets of photo counts. Intra-evaluator and inter-evaluator reliability measures for photo counts were evaluated using calculations of intraclass correlation coefficients (ICCs). RESULTS: Eight subjects (2 males and 6 females) age between 16 and 40 (min 16 years, max 25 years) diagnosed with facial acne vulgaris participated in the study. Fitzpatrick Skin Types ranged from III to V (three Type-III, four Type-IV, and one Type-V). ICC values for intra-evaluator reliability were found to be >0.95 for each evaluator, and ICC for inter-evaluator reliability was found to be 0.98. CONCLUSIONS: Photographic lesion count methodology is a reliable and accurate tool for objective measurement of ALCs and additionally, for training and/or qualifying evaluators.