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

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.