BACKGROUND: The Urticaria Activity Score summed over 7 days (UAS7) assesses the itch severity and hives count in chronic spontaneous urticaria (CSU), using once-or twice daily diary-based documentation.
OBJECTIVE: To evaluate the comparability of twice-daily versus once-daily versions of the UAS and the resulting UAS7 values.
METHODS: Data came from ASSURE-CSU. The twice-daily and once-daily UAS7 was calculated from morning and evening ratings and from exact 24-hour evening ratings of hives count and itch severity, respectively. Three UAS7 scores were computed: UAS7 twice-daily (UAS7TD), UAS7 once-daily for maximum itch (UAS7OD1MAX), and UAS7 once-daily for average itch (UAS7OD2AVG). UAS7 values were assigned to 5 score bands (0, 1-6, 7-15, 16-27, 28-42) reflecting urticaria-free to severe disease activity. The score values and score band ratios of the UAS7TD and UAS7OD versions were compared and assessed for correlation by weighted Cohen’s kappa statistics.
RESULTS: Data from 614 patients were analyzed. All three versions of the UAS7 yielded very similar results, with a mean [SD] UAS7TD, UAS7OD1MAX, and UAS7OD2AVG of 17.3 [10.49], 17.7 [8.90], and 16.2 [8.68], respectively. Correlation coefficients between UAS7TD and UAS7OD1MAX, UAS7TD and UAS7OD2AVG, and UAS7OD1MAX and UAS7OD2AVG were 0.94, 0.95, and 0.99, respectively, showing very high positive pairwise correlation. The weighted kappa coefficient, κ (95% CI) was 0.78 (0.75-0.82) for UAS7TD vs. UAS7OD1MAX and 0.82 (0.78-0.85) for UAS7TD vs. UAS7OD2AVG, demonstrating substantial agreement.
CONCLUSIONS: The once- and twice-daily UAS7 scores were highly consistent, supporting the use of either version when evaluating CSU activity.
