Urticaria Activity Score (UAS)
Stratifies severity of urticaria using daily wheal count and itch severity.
| Daily UAS | Interpretation |
|---|---|
| 0 | None |
| 1–2 | Mild |
| 3–4 | Moderate |
| 5–6 | Severe |
The Urticaria Activity Score (UAS) is the gold-standard clinical tool used to assess the severity of Chronic Spontaneous Urticaria (CSU) and monitor the patient’s response to treatment. Because urticaria (hives) symptoms can fluctuate significantly throughout the day, the UAS relies on patient-reported data over a specific period rather than a single point-in-time physician observation (Zuberbier et al., 2018).
The UAS Scoring System
The UAS evaluates the two primary symptoms of urticaria: Wheals (hives) and Pruritus (itching). Patients record their symptoms once daily based on a 24-hour look-back period.
Daily Scoring Criteria (0–3 points per category)
| Score | Wheals (Hives) | Pruritus (Itching) |
| 0 | None | None |
| 1 (Mild) | < 20 wheals / 24h | Mild (present but not annoying/troublesome) |
| 2 (Moderate) | 20–50 wheals / 24h | Moderate (troublesome but does not interfere with normal activity/sleep) |
| 3 (Severe) | > 50 wheals or large confluent areas | Severe (sufficiently troublesome to interfere with normal activity/sleep) |
The maximum daily score is 6.
UAS7: The Weekly Standard
While a single day’s score provides a snapshot, the UAS7 (the sum of daily scores over seven consecutive days) is the preferred metric for clinical trials and routine management. The UAS7 provides a more stable representation of disease activity.
Interpreting UAS7 Results
The total score ranges from 0 to 42.
- 0: Urticaria-free
- 1 – 6: Well-controlled disease
- 7 – 15: Mild disease
- 16 – 27: Moderate disease
- 28 – 42: Severe disease
Clinical Significance
The UAS7 is essential for guiding therapeutic escalation. According to international guidelines (EAACI/GA²LEN/EDF/WAO), the goal of treatment is “complete symptom control,” defined as a UAS7 score of 0.
If a patient remains in the “moderate” or “severe” category despite standard-dose H1-antihistamines, clinicians use the UAS7 as evidence to justify dose up-titration or the addition of advanced therapies like Omalizumab or Cyclosporine (Zuberbier et al., 2018; Młynek et al., 2008).
Limitations
- Angioedema: The UAS does not account for angioedema (deep tissue swelling). Patients with frequent angioedema should use the Angioedema Activity Score (AAS) in conjunction with the UAS.
- Subjectivity: As a patient-reported outcome, “Pruritus” scores are subjective and can be influenced by the patient’s pain threshold or psychological state.
References
- Zuberbier, T., et al. (2018). The EAACI/GA²LEN/EDF/WAO guideline for the definition, classification, diagnosis, and management of urticaria. Allergy, 73(7), 1393-1414. https://doi.org/10.1111/all.13397
- Młynek, A., et al. (2008). Validity and responsiveness of the urticaria activity score (UAS7) in probiotic treatment of chronic urticaria. Archives of Dermatological Research, 300(7), 353-356. https://doi.org/10.1007/s00403-008-0863-7
- Hawro, T., et al. (2015). The Urticaria Activity Score-Validity, Reliability, and Responsiveness. Journal of Allergy and Clinical Immunology: In Practice, 3(6), 1000-1001.
