Assessing Post-Inflammatory Pigmentation in Atopic Dermatitis: Reliability of the PDCA-Derm™
Introduction: Atopic dermatitis (AD) is a chronic, relapsing, heterogeneous inflammatory disorder. After a flare-up, the affected skin may have areas of post-inflammatory hyper- or hypo-pigmentation (PIH). A new scale, the PDCA-Derm™, assesses PIH by comparing post-inflammatory lesions to adjacent normal skin. This single-item clinician-reported outcome measure addresses a key gap in AD skin assessment. The primary objective of this study was to evaluate qualitative and quantitative data obtained from healthcare providers (HCPs) on the suitability of the PDCA-Derm for use in patients with moderate-to-severe AD. Methods: HCPs recruited were dermatologists who treat patients with moderate-to-severe AD. During individual 60-minute cognitive debriefing meetings, each HCP was asked about their interpretation of the instructions and response options of the PDCA-Derm, and their opinion on its suitability to capture changes in PIH in patients with moderate-to-severe AD of all skin tones. Using a series of photos (n=22), HCPs assessed PIH using the PDCA-Derm at 2 timepoints. The intraclass correlation coefficient (ICC) was used to evaluate intra- and inter-rater reliability. Results: Ten HCPs, all holding a Doctor of Medicine as their highest degree, participated in the study. The mean age of participants was 51.4 years (standard deviation: 13.7), and over half (n=6) were female. Most HCPs reported having 11 or more years of experience practicing in dermatology (n=8). Six HCPs reported that 26–50% of both their patients overall and those with AD were patients with skin of color. PDCA-Derm instructions and response options were correctly interpreted by all HCPs, and all reported the response options were distinct from one another. Seven HCPs indicated the PDCA-Derm was easy to use. Six HCPs indicated the PDCA-Derm could capture PIH, and 5 indicated it had the ability to capture changes to PIH in patients with moderate-to-severe AD. Intra-rater reliability was good to excellent (ICC=0.76–0.99, n=8) for all but 2 HCPs (ICC=0.55 and 0.74). The inter-rater reliability for PIH ranged from good at timepoint 1 (ICC=0.75, n=10) to excellent at timepoint 2 (ICC=0.90, n=10). Conclusion: The PDCA-Derm was well understood by HCPs and had good inter- and intra-rater reliability, supporting its appropriateness for use to assess PIH in moderate-to-severe AD. Additional studies investigating HCP assessment of the PDCA-Derm and its reliability are needed to make solid conclusions about the instrument's validity.
