OBJECTIVE: To evaluate the comparability of two versions of the Urticaria Activity Score Over 7 Days (UAS7) using data from ASSURE-CSU study, the first international study to quantify the humanistic and economic burden of illness of patients with chronic spontaneous urticaria (CSU).
METHODS: This observational, multinational, and multicentre study conducted in Canada, France, Germany, Italy, Netherlands, Spain, and the United Kingdom enrolled patients with CSU aged ≥18 years with disease persisting for ≥12 months and symptomatic despite current treatment. For the UAS7 twice daily (TD), patients documented the number of hives and itch intensity in the past 12 hours every morning and every evening. UAS7 TD score was obtained by adding the score for wheals (0=0 points, <6=1, 6-12=2, >12=3) and the score for itch (none=0 points, mild=1, moderate=2, severe=3) of each morning and each evening every day, calculating the daily average, and then adding the average daily scores of 7 days. For the UAS7 once daily (OD), patients reported the exact 24-hour hive count and itch intensity over the last 24 hours every evening. The UAS7 OD was calculated by adding the daily sum values of wheals (0=0 points, <20=1, 20–50=2, >50=3) and itch (none=0 points, mild=1, moderate=2, severe=3). Both the UAS7 OD and the UAS7 TD range from 0-42. UAS7 scores were grouped in 5 score bands (0, 1-6, 7-15, 16-27, 28-42) reflecting urticaria-free to severe disease activity. Consistency of scores and disease activity score ranges between UAS7 TD and UAS7 OD were evaluated using descriptive statistics, correlation, and weighted Cohen’s kappa statistics.
RESULTS: Analyses were conducted using data from 614 patients. Mean [SD] UAS7 scores were similar when obtained with the UAS7 TD (17.3 [10.49], n=605) and the UAS7 OD (17.7 [8.90], n=504). A very high positive correlation was observed between the two UAS7 scores (r=0.94). Of the 501 patients with nonmissing UAS7 scores on both versions, 388 (77.4%) patients were assigned to the same disease activity score band by the two versions. Of the 113 (22.6%) patients assigned to different score bands by the two versions, the majority (111/113 [98.2%]) were classified in adjacent score bands; 42 (37.8%) of which were in the lower adjacent band and 69 (62.2%) in the higher adjacent band. Scores for these patients tended to cluster near the threshold values for the adjacent bands. The weighted kappa coefficient (κ=0.78) demonstrated substantial agreement between the band classifications based on the two versions.
CONCLUSION: UAS7 scores based on twice-daily versus once-daily hive count questionnaires were highly consistent, providing evidence to support the use of either version when evaluating CSU activity.
