In a recent study, a new picture tool based on patterns demonstrated greater reliability, speed, and user friendliness compared with a digital drawing tool and the fingertip unit to estimate the extent of body surface area (BSA) affected by psoriasis and atopic dermatitis (AD). The tool was also effective for determining appropriate dosage of topical treatments for these patients. Findings from this study were published in the Journal of the European Academy of Dermatology and Venereology.

A total of 11 observers (ie, medical students and dermatologists) were recruited to score 40 psoriasis (n=20) and AD (n=20). Scoring was conducted with either the fingertip unit calculated by the 1% hand rule, a picture-based tool using patterns (cutaneous inflammatory disease extent score [CIDES]), or a digital drawing tool. The picture-based tool consisted of 6 categories “pictured” by patterns common in psoriasis and eczema. Interrater and intrarater reliability as well as timing and user friendliness were tested.

The picture-based tool showed excellent intraclass correlation for the interrater agreement (0.92) and intrarater agreement (0.96). The digital drawing tool had an interrater agreement and intrarater agreement of 0.89 and 0.93, respectively. Increased interrater variability (intraclass correlation, 0.79) and excellent intrarater agreement (intraclass correlation, 0.95) were found for the rule of hands method. The CIDES method was associated with the least variation in calculating the amount of topical treatment needed for patients with psoriasis and AD. All observers agreed that the CIDES was preferable and was relatively fast to perform (median, 30 seconds). The median durations of a score were 57 seconds, 42 seconds, and 89 seconds for the rule of hands, CIDES, and the drawing tool, respectively.

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Limitations of the study were the small sample size as well as the inclusion of only white patients.

“Given these superior characteristics,” the researchers wrote, “this instrument can be used to calculate the affected BSA in inflammatory skin disorders and will be integrated in a new digital tool to determine the dosage of topical treatments.”

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Reference

Speeckaert R, Hoorens I, Corthals S, et al. Comparison of methods to estimate the affected body surface area and the dosage of topical treatments in psoriasis and atopic dermatitis: the advantage of a picture-based tool [published online June 5, 2019]. J Eur Acad Dermatol Venereol. doi:10.1111/jdv.15726.