OBJECTIVES: The Urticaria Activity Score (UAS) comprises patient-reported items of itch severity and number of hives and is the criterion standard for assessing disease activity in chronic spontaneous urticaria (CSU). Data from twice-daily completion of the UAS in two phase 3 clinical trials were used to evaluate the reliability, validity, and responsiveness of weekly scores derived from the measure.
METHODS: Initial pooled data over 12 weeks from two phase 3 trials in adults with CSU (REMIX-1[NCT05030311]) and REMIX-2[NCT05032157] were used for the analysis. Evaluations of weekly UAS (UAS7; 0-42), Itch Severity Score (ISS7; 0-21), and Hives Severity Score (HSS7; 0-21) included test-retest reliability intraclass correlation coefficients (ICCs), construct validity and responsiveness correlations, and known-groups and responsiveness-groups analysis (analysis of variance). Supporting measures included Patient Global Impression of Severity (PGIS), Patient Global Impression of Change (PGIC), Dermatology Life Quality Index (DLQI; total score, score bands), and Urticaria Control Test 7-day recall.
RESULTS: The analysis sample included 889 patients (66.3% female; mean [standard deviation] age=43.4 [14.3] years). Scores were available for n=889 at baseline, n=882 at week 2, n=872 at week 4, and n=743 at week 12. Test-retest ICCs for scores at weeks 2 and 4 for patients with no change on PGIS and PGIC were ≥ 0.85. Convergent and responsiveness correlations with DLQI, UCT7, PGIS, and PGIC were ≥ 0.3. Differences (all P values < 0.0001) were found between groups based on DLQI, UCT7, PGIS, and rescue medication use at baseline, week 2, and/or week 12. Additionally, improved subgroups on the DLQI total score band, PGIS, and PGIC at weeks 2 and/or 12 had significantly greater improvements on the UAS7, ISS7, and HSS7.
CONCLUSIONS: The analyses confirmed the strong reliability, construct validity, and responsiveness of the UAS7, ISS7, and HSS7, supporting their use to assess treatment benefit in CSU clinical trials.
