Clinical FeaturesImmunology

Latest Advances in Chronic Spontaneous Urticaria (CSU)

Written by Dr Katie Ridge & Dr Niall Conlon, Department of Immunology, St James’s Hospital, Dublin/Trinity College Dublin

Chronic spontaneous urticaria (CSU) is a common but poorly recognised skin condition affecting children and adults with an estimated prevalence of 1%. 1 It is characterised by unpredictable eruptions of itchy hives. Swelling of the skin or mucous membranes. These are known as angioedema is seen in approximately half of all cases. CSU is distressing for patients. It is associated with markedly impaired quality of life and psychological comorbidity. 2,3 This often neglected disorder has higher point prevalence in females. 4

The primary effector cell in CSU is the mast cell.

Mast cell degranulation in CSU is multifactorial. Novel mechanisms at play include ‘autoallergy’ whereby IgE is directed against an element of self. Or by autoimmunity whereby IgG is directed against IgE or its receptor. 5 Our improved understanding of underlying pathology has helped us to differentiate this condition from other allergic diseases.

Despite this, misconceptions are common. Both patients and health care providers can interpret the symptoms of CSU as representing evidence of food allergy. This leads to inappropriate testing for food sensitisation and can result in unnecessarily restricted diets and increased patient anxiety. Time to diagnosis can be prolonged and patients typically report multiple healthcare attendances before a diagnosis is established. In Europe, the mean time to diagnosis is 2-4 years. 6

The first-line treatment for CSU is second generation antihistamines.

However, a high proportion of patients will not respond to antihistamine treatment even when prescribed at high doses. Omalizumab is a safe and effective monoclonal antibody directed against IgE. It is recommended in CSU that is refractory to high dose antihistamines. 7 It is however a high cost medicine. It typically requires specific funding approval with in-hospital administration and monitoring. Thus demanding administrative and clinical support. In Ireland, patient access to omalizumab in refractory CSU is allocated on a case by case basis in a handful of specialist centres.

A recent study conducted at St. James’s Hospital revealed the high number of unplanned healthcare attendances seen in patients with CSU when their disease is active. 8 Importantly, the study demonstrated a dramatic reduction in unplanned healthcare interactions after commencing omalizumab, with a 98% reduction in ED attendances and a 97.7% reduction in GP attendances. These data suggest that omalizumab, delivered in a specialist centre, may benefit patients with CSU. This is through reducing disease activity and reducing the need for unscheduled care.

The transition towards self-administration of omalizumab provides an opportunity for understanding how the delivery of this treatment can be optimised in an Irish setting.9,10

Patient satisfaction surveys have established that home administration is largely favoured by patients over hospital attendance. 10 Importantly, omalizumab has changed the landscape for this cohort of patients, the majority of whom will experience a significant improvement in symptoms and quality of life following anti IgE treatment.


  1. Fricke J, Ávila G, Keller T, Weller K, Lau S, Maurer M, et al. Prevalence of chronic urticaria in children and adults across the globe: Systematic review with meta-analysis. Allergy. 2020 Feb;75(2):423–32.
  2. Maurer M, Abuzakouk M, Bérard F, Canonica W, Oude Elberink H, Giménez-Arnau A, et al. The burden of chronic spontaneous urticaria is substantial: Real-world evidence from ASSURE-CSU. Allergy. 2017 Dec;72(12):2005–16.
  3. Tzur Bitan D, Berzin D, Cohen A. The association of chronic spontaneous urticaria (CSU) with anxiety and depression: a nationwide cohort study. Arch Dermatol Res. 2021 Jan;313(1):33–9.
  4. Savic S, Leeman L, El-Shanawany T, Ellis R, Gach JE, Marinho S, et al. Chronic urticaria in the real-life clinical practice setting in the UK: results from the noninterventional multicentre AWARE study. Clin Exp Dermatol. 2020 Dec;45(8):1003–10.
  5. Church MK, Kolkhir P, Metz M, Maurer M. The role and relevance of mast cells in urticaria. Immunol Rev. 2018 Mar;282(1):232–47.
  6.  Lacour J-P, Khemis A, Giordano- Labadie F, Martin L, Staumont- Salle D, Hacard F, et al. The burden of chronic spontaneous urticaria: unsatisfactory treatment and healthcare resource utilization in France (the ASSURE-CSU study). Eur J Dermatol EJD. 2018 Dec 1;28(6):795–802.
  7. Zuberbier T, Abdul Latiff AH, Abuzakouk M, Aquilina S, Asero R, Baker D, et al. The international EAACI/GA2LEN/EuroGuiDerm/ APAAACI guideline for the definition, classification, diagnosis, and management of urticaria. Allergy. 2022 Mar;77(3):734–66.
  8. Ridge K, Redenbaugh V, Conlon N. Omalizumab Reduces Unplanned Healthcare Interactions in Irish Patients With Chronic Spontaneous Urticaria. Front Allergy. 2021 Dec 23;2:810418.
  9. Denman S, El-Shanaway T, Carne E, Devlin L, Savic S. Multicentre experience of home omalizumab treatment for chronic spontaneous urticaria. Eur J Hosp Pharm Sci Pract. 2020 Nov;27(6):367–8.
  10. King C, Cox F, Sloan A, McCrea P, Edgar JD, Conlon N. Rapid transition to home omalizumab treatment for chronic spontaneous urticaria during the COVID-19 pandemic: A patient perspective. World Allergy Organ J. 2021 Oct;14(10):100587.

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