An Assessment of Skin Lesion Measurement Techniques for Use in Clinical Trials of Acute Bacterial Skin and Skin Structure Infections
BackgroundLimited data are available to support a reproducible measurement technique that could be used to assess the response of a skin lesion associated with a bacterial infection to antibacterial therapy.\n\nMethodsThis multicenter, observational study enrolled patients with a major cutaneous abscess, a traumatic wound or surgical site infection, or a cellulitis. The primary objective was to characterize the intra- and inter-observer variability inherent in measuring the size of the erythema associated with the presenting skin infection. At least two observers made ruler measurements of the infection site with the length of the infection measured as the longest dimension of the erythematous area and width measured as the largest dimension perpendicular to the longest length. Intra- and inter-observer variability was determined by the intraclass correlation coefficient (ICC). Photographs, tracings, and thermal imaging were also performed.\n\nResultsThe intra-observer ICC (95% CI) for lesion area as measured by ruler was 0.999 (0.998, 0.999), suggesting only a very small amount of the variability was due to measurement error. The difference in mean lesion area measurements by the same observer was <1%. The inter-observer ICC (95% CI) for lesion area as measured by ruler was 0.990 (0.981, 0.995) suggesting that the results between observers were also highly reliable.\n\nConclusionsMeasurement of infection area as defined by erythema and measured by ruler shows excellent intra- and inter-observer reliability and can be used in future clinical trials of acute bacterial skin infections.