The reliability and validity of outcome measures for atopic dermatitis in patients with pigmented skin: A grey area

C Y Zhao; A Wijayanti; M C Doria; A G Harris; S V Jain; K N Legaspi; N C Dlova; M G Law; D F Murrell

doi:10.1016/j.ijwd.2015.05.002

The reliability and validity of outcome measures for atopic dermatitis in patients with pigmented skin: A grey area

Int J Womens Dermatol. 2015 Aug 6;1(3):150-154. doi: 10.1016/j.ijwd.2015.05.002. eCollection 2015 Aug.

Authors

C Y Zhao^{1

2}, A Wijayanti², M C Doria^{1

2}, A G Harris^{1

2}, S V Jain², K N Legaspi^{1

2}, N C Dlova³, M G Law⁴, D F Murrell^{1

2}

Affiliations

¹ Department of Dermatology, St. George Hospital, Sydney, Australia.
² Faculty of Medicine, University of New South Wales, Sydney, Australia.
³ Derpartment of Dermatology, Nelson R. Mandela School of Medicine, University of KwaZulu-Natal, Durban, South Africa.
⁴ Kirby Institute, University of New South Wales, Sydney, Australia.

Abstract

Background: Outcome measures for atopic dermatitis (AD) patients with pigmented skin have neither been developed nor validated.

Objective: To compare the reliability and validity of four common AD outcome measures in patients with various levels of skin darkness.

Method: The inter- and intra-rater reliability and construct validity of the EASI (Eczema Area and Severity Index), objective-SCORing Atopic Dermatitis (oSCORAD), Three Items Severity index (TIS) and Six Areas, Six Sites Atopic Dermatitis (SASSAD) were evaluated in 18 patients of various levels of skin darkness, using their full body photographs, by five trained clinicians.

Results: The inter-rater reliability intraclass coefficient (ICCs) and 95% confidence intervals were poor for highly pigmented patients: EASI -.054(-.200 to .657), oSCORAD -.089(-.206 to .598), TIS -.21(-.24 to .147), SASSAD -.071(-.200 to .631); fair for mildly pigmented patients: EASI .464(.140-.839), oSCORAD .588(.265-.89), TIS.524(.200-.865), SASSAD .41(.045-.775); and fair to good for non-pigmented patients: EASI .64(.330-.908), oSCORAD .586(.263-.889), TIS .403(.09-.809), SASSAD .667(.358-.916). Erythema likely contributed to the inter-rater variability. Construct validity had significant correlations across all measures in non-pigmented patients, but no correlations in highly pigmented patients.

Conclusion: AD outcome measures have poor reliability and validity in highly pigmented patients, with variations in erythema perception being a contributor.

Keywords: Atopic dermatitis; Outcome measures; Skin of color.