Consensus guidelines from the European Academy of Allergology and Clinical Immunology, Global Allergy and Asthma European Network, European Dermatology Forum, and World Allergy Organization (EAACI/GA2LEN/EDF/WAO) recommend using a direct well-established scale such as the Urticaria Activity Score (UAS), which evaluates the main disease characteristics (itch, presence, and number of wheals) on a Likert-type symptom intensity scale (0 to 3), with a total daily score ranging from 0 to 6.
The UAS has been used in numerous controlled clinical trials and in daily clinical practice. It was recently validated specifically for the follow-up and monitoring of CU activity, with the explicit recommendation that it would be used for at least 4 consecutive days or, preferably, for 1 week (UAS 7).
Score -- Wheals or hives -- Itch
0 -- None -- None
1 -- Mild (less than 20 wheals/24 h) -- Mild
2 -- Moderate (21-50 wheals/24 h) -- Moderate
3 -- Intense or severe (>50 wheals/24 h -- Intense or large confluent areas of wheals) or severe
The UAS assigns a score from 0 (no disease activity) to 3 (intense activity) for each of the 2 key urticaria symptoms, wheals and pruritus. The sum of the scores represents disease severity on a scale from 0 (minimum) to 6 (maximum).
Chronic Urticaria Treatment Options in 6 Steps (click to enlarge the image). En Español.
Assessment of Severity and Quality of Life in Chronic Urticaria. J Investig Allergol Clin Immunol 2014; Vol. 24(2): 80-86.
How to assess disease activity in patients with chronic urticaria? - Młynek - 2008 - Allergy - Wiley Online Library http://buff.ly/1qm49Pr
Image source: Urticaria, Wikipedia, public domain.