Identifying the best predictive diagnostic criteria for psoriasis in children (< 18 years): A UK multicentre case-control diagnostic accuracy study (DIPSOC study)

Abstract

BACKGROUND: In children, psoriasis can be challenging to diagnose. Difficulties arise from differences in the clinical presentation compared with adults., OBJECTIVES: To test the diagnostic accuracy of previously agreed consensus criteria and to develop a shortlist of the best predictive diagnostic criteria for childhood psoriasis., METHODS: A case-control diagnostic accuracy study in 12 UK dermatology departments (2017-2019) assessed 18 clinical criteria using blinded trained investigators. Children (< 18 years) with dermatologist-diagnosed psoriasis (cases, N = 170) or a different scaly inflammatory rash (controls, N = 160) were recruited. The best predictive criteria were identified using backward logistic regression, and internal validation was conducted using bootstrapping., RESULTS: The sensitivity of the consensus-agreed criteria and consensus scoring algorithm was 84.6%, the specificity was 65.1% and the area under the curve (AUC) was 0.75. The seven diagnostic criteria that performed best were: (i) scale and erythema in the scalp involving the hairline, (ii) scaly erythema inside the external auditory meatus, (iii) persistent well-demarcated erythematous rash anywhere on the body, (iv) persistent erythema in the umbilicus, (v) scaly erythematous plaques on the extensor surfaces of the elbows and/or knees, (vi) well-demarcated erythematous rash in the napkin area involving the crural fold and (vii) family history of psoriasis. The sensitivity of the best predictive model was 76.8%, with specificity 72.7% and AUC 0.84. The c-statistic optimism-adjusted shrinkage factor was 0.012., CONCLUSIONS: This study provides examination- and history-based data on the clinical features of psoriasis in children and proposes seven diagnostic criteria with good discriminatory ability in secondary-care patients. External validation is now needed. Copyright © 2021 The Authors. British Journal of Dermatology published by John Wiley & Sons Ltd on behalf of British Association of Dermatologists.