Measurement properties of the PROMIS Itch Questionnaire - itch severity assessments in adults with atopic dermatitis.

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 examinations were performed in 410 patients with AD (aged 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.