Analysis of disease activity categories in chronic spontaneous/idiopathic urticaria

Measurement of disease activity guides treatment of chronic spontaneous urticaria (CSU). A weekly Urticaria Activity Score - here, the average of twice-daily patient assessment of itch and hives scores summed over 1 week (UAS7_TD ) - measures severity from 0 to 42. Insufficient evidence exists on whether disease activity states, defined by categorical UAS7_TD scores, correlate with other patient-reported outcomes and treatment response.

To evaluate and compare categorical UAS7_TD scores with selected measures of disease-related quality of life and impact.

Data from three randomized clinical trials of omalizumab in CSU were pooled. Continuous UAS7_TD scores were categorized into five disease activity states: urticaria-free, well-controlled, mild, moderate and severe urticaria. Total scores from the Dermatology Life Quality Index; the Chronic Urticaria Quality of Life questionnaire; and questions on sleep and daily activity interference, presence of angioedema and diphenhydramine use were compared within categorized UAS7_TD disease-state scores, using anova for analysis at different time points and mixed-effects regressions for analysis of all data pooled.

Pooled analyses showed that categorical UAS7_TD disease states accurately predicted differences among treated patients with CSU with different levels of disease activity. A consistent pattern existed between categories, with higher-activity disease states associated with significantly higher impact and an increase in angioedema frequency. Results at different treatment time points were consistent.

Categorical UAS7_TD disease states can discriminate between measures when considering the impact of urticaria activity. Using five categorical disease states could simplify clinical assessment and monitoring of treatment efficacy.