Validity and responsiveness of the Urticaria Activity and Impact Measure: A new patient-reported tool.

BACKGROUND: Chronic spontaneous urticaria (CSU), also known as chronic idiopathic urticaria, may produce hives, itch, and angioedema. The Urticaria Activity and Impact Measure (U-AIM) is a newly developed 9-item patient-reported measure designed for use in routine clinical practice to assess CSU activity and impact during the previous 7 days.

OBJECTIVE: To evaluate validity, responsiveness, and clinically meaningful change of the U-AIM.

METHODS: Data from a 24-week, open-label, single-arm period of a randomized, placebo-controlled study of omalizumab were used to assess the psychometric properties of U-AIM items for itch, hives, and angioedema.

RESULTS: A total of 206 patients (75% female; mean age, 44.6 years) were enrolled. At baseline, U-AIM results included prevalent severe itch (55%) and more than 12 hives (67%), angioedema (15%), and bother by itch (84%), hives (84%), and angioedema (49%). The Urticaria Patient Daily Diary (UPDD) mean weekly scores were 15.4 (itch severity), 16.8 (number of hives), and 32.2 (Urticaria Activity Score [UAS7]). At baseline, week 12, and week 24, U-AIM itch and hives items and UAS7 proxy scores (the sum of itch severity and number of hives during 7 days) demonstrated strong correlation coefficients with their corresponding measures from the UPDD (itch severity: 0.634-0.806; hives number: 0.735-0.843; UAS7 proxy: 0.724-0.852). Changes in U-AIM scores differentiated patients by their perspective of symptom improvement. Meaningful change thresholds were established for itch severity and number of hives scores (range, 0.8-1.0 for both) and the UAS7 proxy score (range, 10.5-12.5).

CONCLUSION: The U-AIM is valid and responsive to change and may help clinicians monitor CSU activity and track treatment effectiveness.