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

Abstract

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. 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. 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. 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). 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.