Comparison of Urticaria Activity Score Over 7 Days (UAS7) Values Obtained from Once-Daily and Twice-Daily Versions: Results from the ASSURE-CSU Study.

BACKGROUND

The Urticaria Activity Score summed over 7 days (UAS7) assesses the itch severity and hive count in chronic spontaneous urticaria (CSU) using once- or twice-daily diary-based documentation.

OBJECTIVE

The aim of this study was to evaluate the comparability of twice-daily versus once-daily versions of the UAS and the resulting UAS7 values.

METHODS

Data came from the ASSURE-CSU study. The twice-daily and once-daily UAS7 was calculated from morning and evening ratings, as well as from exact 24-h evening ratings of hive count and itch severity, respectively. Three UAS7 scores were computed: UAS7 twice daily (UAS7), UAS7 once daily for maximum itch (UAS7), and UAS7 once daily for average itch (UAS7). UAS7 values were assigned to five 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 UAS7 and UAS7 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 (standard deviation) UAS7, UAS7, and UAS7 of 17.3 (10.49), 17.7 (8.90), and 16.2 (8.68), respectively. Correlation coefficients between UAS7 and UAS7, UAS7 and UAS7, and UAS7 and UAS7 were 0.94, 0.95, and 0.99, respectively, showing very high positive pairwise correlation. The weighted kappa coefficient, κ (95% confidence interval) was 0.78 (0.75-0.82) for UAS7 versus UAS7, and 0.82 (0.78-0.85) for UAS7 versus UAS7, demonstrating substantial agreement.

CONCLUSIONS

The once- and twice-daily UAS7 scores were highly consistent, supporting the use of either version when evaluating CSU activity.