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

Abstract

BackgroundOutcome measures for atopic dermatitis (AD) patients with pigmented skin have neither been developed nor validated.ObjectiveTo compare the reliability and validity of four common AD outcome measures in patients with various levels of skin darkness.MethodThe 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.ResultsThe 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.ConclusionAD outcome measures have poor reliability and validity in highly pigmented patients, with variations in erythema perception being a contributor.

A comparison study of clinician-rated atopic dermatitis outcome measures for intermediate- to dark-skinned patients

“…As opposed to findings from a previous similar study performed using full‐body photographs of patients with AD, in patients with SOC, erythema perception was not found to be a contributor to the inter‐rater variability in the EASI or oSCORAD. Surprisingly, in lighter‐skinned patients, the EASI score's erythema component reduced its inter‐rater variability (i.e.…”

“…The reliabilities of EASI and oSCORAD were shown to be much higher in our study than in a previous study performed using photographs, where the reliabilities of all clinician‐rated AD outcome measures were poor in patients with SOC, and were either fair or good in light‐skinned patients . Another problem with photographs is assessing the area involved, as all areas of the skin and folds are harder to appreciate than with patients examined in person.…”

“…A previous study that we conducted using full‐body photographs of patients with AD showed that both EASI and oSCORAD have poor reliability in patients with SOC, with distortion in erythema scoring being a contributing factor. However, the validity of the study was rightly criticized as it was limited by utilizing photographs instead of real‐life patients with AD …”

Approach to the Assessment and Management of Pediatric Patients With Atopic Dermatitis: A Consensus Document. Section I: Overview of Pediatric Atopic Dermatitis

“…53 This is contrary to previous studies which demonstrated poor reliability in pigmented skin. 54 Despite the strong performance of EASI in trials, it is more cumbersome to conduct than the Physician Global Assessment (PGA) in clinical practice. PGA, also known as the Investigator Global Assessment (IGA), is considered easier to conduct and more clinically relevant compared to other investigator assessments.…”

Developing drugs for treatment of atopic dermatitis in children (≥3 months to <18 years of age): Draft guidance for industry

“…Although the morphology of AD varies according to Fitzpatrick skin phototype, an accurate diagnosis of AD can still be made using the Hanifin‐Rajka criteria or the American Academy of Dermatology consensus criteria, although investigators should be made aware that patients with darker skin (higher Fitzpatrick skin phototype) often have less visibly apparent erythema, more lichenification, greater follicular prominence, and more areas of dyspigmentation. Data are conflicting with regard to the performance of current scoring systems (including EASI and SCORAD) for patients with highly pigmented skin …”