Severity strata for five patient-reported outcomes in adults with atopic dermatitis

Abstract

Background: Several patient-reported outcomes have been used to assess the burden of atopic dermatitis (AD). Some are disease specific, such as the Patient-Oriented Eczema Measure (POEM), while others pertain to itch, for example the numerical rating scale (NRS)-itch, ItchyQoL and 5-D itch, or dermatological disease in general, for example the Dermatology Life Quality Index (DLQI). Development of severity strata is essential for proper interpretability of these assessments. Objectives: To confirm previously developed strata for POEM, DLQI and raw ItchyQoL, and develop strata for the NRS-itch, mean ItchyQoL and 5-D itch scale for use in adults with AD. Methods: Self-administered questionnaires were completed by 210 adults with AD in a dermatology practice setting. Strata were selected using an anchoring approach based on patient-reported disease severity. Results: We confirmed the existing strata for POEM (mild 0–7, moderate 8–16, severe 17–28; κ = 0·440), DLQI (mild 0–5, moderate 6–10, severe 11–30; κ = 0·398) and NRS-itch (mild 0–3, moderate 4–6, severe 7–10; κ = 0·499). However, the preferred band for raw ItchyQoL was mild 22–58, moderate 59–74 and severe 75–110 (κ = 0·379) and for mean ItchyQoL, mild 1–2·9, moderate 3·0–3·9, severe 4·0–5·0 (κ = 0·374). The preferred band for 5-D itch scale was mild 0–11, moderate 12–17 and severe 18–25 (κ = 0·331). Conclusions: Existing strata for POEM and DLQI performed well in adult AD. Previously reported strata for visual analogue scale-itch performed best for NRS-itch. We identified banding for the raw ItchyQoL for our AD population that varies slightly from the banding published for a more heterogeneous population. Finally, we proposed strata for mean ItchyQoL and 5-D itch scale in adult AD.