Developing and validating the CWARTS diagnostic tool, a novel clinical assessment and classification system for cutaneous warts

Abstract

Background

The clinical appearance of cutaneous warts is highly variable and not standardised.

Objectives

The aim of this study was to develop and validate a reproducible clinical tool for the standardised assessment of cutaneous warts to distinguish these lesions accurately.

Methods

Nine morphological characteristics were defined and validated regarding intra- and inter-observer agreement. Based on literature and semi-structured interviews, a systematic dichotomous assessment tool, the Cutaneous WARTS diagnostic tool (CWARTS diagnostic tool) was developed. The validation consisted of two independent parts performed with photographs from the recent WARTS-2 trial. In part A, the CWARTS diagnostic tool was tested by 28 experienced physicians who assessed photographs of 10 different warts to investigate inter-observer concordance. In part B, morphological characteristics were validated by blinded and independent scoring of 299 photographs by 6 different observers. Part B also entailed re-assessment of the photographs after at least 1 week. Primary outcome measurement was the intraclass correlation coefficient (ICC).

Results

Presence of black dots (capillary thrombosis) had the greatest ICC (0.85) for inter-observer agreement in part A, followed by arrangement (0.65), presence of border erythema(0.64) and sharpness of the border (0.60). In part B results were similar for inter-observer agreement with presence of black dots having the highest ICC (0.68), followed by border erythema (0.64), arrangement (0.58) and colour (0.55). For intra-observer agreement, presence of black dots had the highest agreement (0.69), followed by presence of border erythema (0.64) and colour (0.55).

Conclusions

The wart phenotype can be reliably assessed by the CWARTS diagnostic tool.

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