Comparison and interpretability of the available urticaria activity scores.

The urticaria activity score (UAS) is the gold standard for assessing disease activity in patients with chronic spontaneous urticaria (CSU). Two different versions, the UAS7 and UAS7TD , are currently used in clinical trials and routine care. To compare both versions and to obtain data on their interpretability, 130 CSU patients applied both versions and globally rated their disease activity as none, mild, moderate, or severe. UAS7 and UAS7TD values correlated strongly (r = .90, P < .001). Interquartile ranges for UAS7 and UAS7TD values for mild, moderate, and severe CSU were 11-20 and 10-24, 16-30 and 16-32, and 27-37 and 28-40. UAS7 values were slightly, but significantly lower as compared to UAS7TD values (mean difference: 1.6 ± 4.6, P < .001). This difference was driven by lower wheal subscores (2.1 ± 3.5, P < .001) and was most pronounced in patients with severe CSU (2.5 ± 5.6, P < .01). The UAS7/UAS7TD ratio was 0.96 ± 0.21 and did not differ significantly between mild, moderate, and severe CSU. Since the results of both UAS versions are comparable, we recommend the use of the UAS7, which is less burdensome in administration and scoring.