Evaluation of the reliability of the Cutaneous Dermatomyositis Disease Area and Severity Index and the Cutaneous Assessment Tool-Binary Method in juvenile dermatomyositis among paediatric dermatologists, rheumatologists and neurologists.

BACKGROUND: The Cutaneous Dermatomyositis Disease Area and Severity Index (CDASI) and Cutaneous Assessment Tool-Binary Method (CAT-BM) have been shown to be reliable and valid outcome measures to assess cutaneous disease in adult dermatomyositis (DM) and juvenile DM (JDM), respectively.

OBJECTIVES: This study compared the CDASI and CAT-BM for use by paediatric dermatologists, paediatric rheumatologists and paediatric neurologists in patients with JDM.

METHODS: Five paediatric dermatologists, five paediatric rheumatologists and five paediatric neurologists each evaluated 14 patients with JDM using the CDASI, CAT-BM, and skin Physician Global Assessment (PGA) scales. Inter-rater reliability, intra-rater reliability, construct validity and completion time were compared.

RESULTS: Inter-rater reliability for CDASI activity and damage scores was good to moderate for paediatric dermatologists and rheumatologists, but poor for paediatric neurologists. The inter-rater reliability for CAT-BM activity scores was moderate for paediatric dermatologists and rheumatologists, but poor for paediatric neurologists and poor across all specialties for damage scores. Intra-rater reliability for the CDASI and CAT-BM activity and damage scores was moderate to excellent for paediatric dermatologists, rheumatologists and neurologists. Strong associations were found between skin PGA activity and damage scores and CDASI or CAT-BM activity and damage scores, respectively (P < 0·002). The CDASI had a mean completion time of 5·4 min compared with that for the CAT-BM of 3·1 min.

CONCLUSIONS: Our data confirm the reliability of the CDASI activity and damage scores and the CAT-BM activity scores when used by paediatric dermatologists and rheumatologists in assessing JDM. Significant variation existed in the paediatric neurologists' scores.