What investigations should I consider for a patient with chronic urticaria that is unresponsive to standard treatment?

For a patient with chronic urticaria that is unresponsive to standard treatment, several investigations and assessments should be considered, primarily leading to specialist referral.

• If a cause for recurrent or persistent urticaria cannot be identified from the patient's history, it is appropriate to consider arranging investigations ¹.
• Assessment Tools: Symptom diaries are useful to determine the frequency, duration, and severity of urticarial episodes ¹. The Urticaria Activity Score (UAS7) can be used to assess the severity of urticaria ¹. Additionally, the Chronic Urticaria Quality of Life Questionnaire (CU-Q2oL) or the Urticaria Control Test (UCT) can assess the impact of urticaria on the patient's quality of life ¹.
• Drug Review: If a drug, such as a nonsteroidal anti-inflammatory drug (NSAID), is suspected to be associated with chronic urticaria, a trial period of several weeks without the medication should be considered ¹.
• Food Allergy: If food allergy is suspected, particularly in children and young people, investigations may include skin prick tests and/or blood tests for specific IgE antibodies to suspected foods ². It is important not to use serum-specific IgG testing for diagnosing food allergy ².
• Specialist Referral: For patients whose symptoms are not well controlled on antihistamine treatment, referral to a dermatologist or immunologist is recommended ¹. These specialists will then guide further investigations and management options ¹.