Oral Presentation 2015 Annual Meeting of the Australasian Society for Dermatology Research

Atopic dermatitis severity scales: a comparison between four scales and evaluation of their use in patients with skin of colour (#24)

Cathy Y Zhao 1 2 , Ahn QT Tran 2 , Melanie J Doria 1 2 , Adam G Harris 1 2 , Swaranjali V Jain 2 , Kristine Legaspi , Ncoza Dlova 3 , Joanna Lazo-Dizon , Jaehwan Kim 1 , Benjamin S Daniels 1 2 , Supriya S Venugopal 1 2 , Lesley Rhodes 1
  1. St George Hospital, Sydney, Australia, Sydney, NSW -, Australia
  2. Medicine, University of New South Wales, Sydney, NSW - New South Wales, Australia
  3. Dermatology, Nelson R Mandela School of Medicine, University of KwaZulu-Natal, Durban, South Africa

Background: The standardisation of atopic dermatitis (AD) outcome measures is crucial, as it allows clinical trial results to be compared and pooled for meta-analyses. Four frequently used clinician-rated AD scales include the objective Scoring Atopic Dermatitis (oSCORAD), Eczema Area and Severity Index (EASI), Six Area, Six Sign Atopic Dermatitis (SASSAD) and Three Item Severity index (TIS). These scales have neither been directly compared yet, nor validated for skin of colour.

Objectives:

1.       To compare the reliability of the oSCORAD, EASI, SASSAD and TIS overall, and in skin of colour.

2.       To correlate these scales to patient-rated QoL instruments.

3.       To evaluate the effect of body surface area (BSA) estimation and erythema perception on inter-rater variations.

Method:  Five trained clinicians scored 12 AD patients, and then rescored at least 4 patients in a one-day scoring exercise. A similar exercise was re-performed on full-body photos of AD patients with various skin darkness levels. Inter-rater and intra-rater reliability were analysed using the intra-class correlation coefficient (ICC). Correlation between scales was analysed using the Spearman’s rho. The effect of BSA or erythema was analysed using the co-efficient of variation (CV).

Results: Inter-rater ICCs were superior in the EASI(0.730) and SASSAD(0.680) than the TIS(0.487) and oSCORAD(0.498). BSA component contributed to oSCORAD’s inter-rater variations. EASI, TIS and SASSAD showed superior intra-rater ICCs of 0.886, 0.820 and 0.720 than oSCORAD’s 0.446. Only the SASSAD correlated with the SkinDex-29, rho=0.611(p=0.035), but no other scales correlated to any other patient-reported instruments. All scales’ inter-rater reliabilities were unacceptably poor for very dark patients(all <0.100) and erythema perception has contributed to this. Construct validity was significant in light skin patients but non-significant in very dark patients.

Conclusion: The EASI is the optimal severity scale for AD clinical trials. No scale is reliable or valid in patients with very dark skin.

  1. Chalmers, J. R., et al. (2014). "Report from the Third International Consensus Meeting to Harmonise Core Outcome Measures for Atopic Eczema / Dermatitis Clinical Trials (HOME)." Br J Dermatol.