Measurement properties of the Patient‐Reported Outcomes Information System (PROMIS®) Itch Questionnaire: itch severity assessments in adults with atopic dermatitis*

Abstract

Background Little is known about the validity of numeric and verbal rating scales (NRS and VRS) for itch and itch frequency for assessing itch severity in AD. We evaluated the Patient‐Reported Outcomes Information System (PROMIS^®) Itch Questionnaire (PIQ) – itch severity assessment, including multiple NRS, VRS and frequency of itch assessments, in adults with AD and compared their performance. Methods Self‐administered questionnaires and skin‐examination were performed in 410 AD patients (age 18‐90 years) in a dermatology practice setting. Results PIQ NRS, VRS and frequency of itch had good content validity; strong correlations with each other (Spearman correlations, P<0.0001) and weak‐moderate correlations with POEM, EASI, objective‐SCORAD, and DLQI (P<0.0001); and very good discriminant validity. Changes from baseline in NRS, VRS and frequency of itch were moderately to strongly correlated with each other, weakly to moderately correlated with other patient‐reported (POEM, SCORAD‐itch, DLQI) and clinical‐reported outcomes (EASI, objective‐SCORAD). NRS and VRS worst‐ and average‐itch showed moderate to good test‐retest reliability. There were no floor or ceiling effects for NRS or VRS itch, but there were ceiling effects for itch frequency. Each assessments was completed in <1 minute by all patients. Conclusions NRS, VRS and frequency of itch from PIQ – itch severity showed good content and construct validity, reliability, and/or responsiveness in adults with AD, and were feasible for use in clinical trials and practice.