Analysis of Disease Activity Categories in Chronic Spontaneous/Idiopathic Urticaria

Abstract

Background

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 whether disease activity states, defined by categorical UAS7_TD scores, correlate with other patient-reported outcomes and treatment response.

Objective

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

Methods

Data from three randomised clinical trials of omalizumab in CSU were pooled. Continuous UAS7_TD scores were categorised into five disease activity states: urticaria-free, well-controlled, mild, moderate, and severe urticaria. Total scores from the Dermatology Life Quality Index (DLQI); the Chronic Urticaria Quality of Life questionnaire (CU-Q₂oL); and questions on sleep and daily activity interference, presence of angioedema, and diphenhydramine use were compared within categorised UAS7_TD disease-state scores, using one-way analyses of variance for analysis at different time points and mixed-effects regressions for analysis of all data pooled.

Results

Pooled analyses showed that categorical UAS7_TD disease states accurately predicted differences among treated CSU patients 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.

Conclusion

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.

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