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The information - urticaria

Allergy specialist Professor Richard Powell offers his advice on a case of urticaria, using PUNS and DENS.

 

The patient’s unmet needs (PUNs)

A 49-year-old woman attends saying ‘that rash keeps coming back, doctor’.  She initially presented about six weeks ago with her first ever episode of urticaria. It was so itchy and widespread that she had made an urgent appointment on the first day of the rash. There was no obvious allergen and she was otherwise well, so you gave her general advice and suggested an antihistamine. But her problem has persisted, with itchy wheals appearing on most days since she was first seen. She has a history of hypertension, and has been taking perindopril and amlodipine for the last couple of years.

 

The doctor’s unmet needs (DENs)

How long do most cases of urticaria last?  In terms of duration and periodicity, how is urticaria classified?

This woman has chronic spontaneous urticaria, which affects about 1% of individuals and often lasts five years or more. This condition causes daily – or almost daily – itchy, red, raised hives, welts or nettle rash lasting for more than six weeks. Some patients with this condition have a more episodic or intermittent urticaria lasting for hours or days but recurring over months or years.  

This is in contrast to acute urticaria, where a single episode occurs and resolves in under six weeks. Many patients will have a trigger for their chronic urticaria, such as heat, cold, pressure, vibration or water. These triggers do not influence the patient’s initial management but are markers for resistant or persisting urticaria, as is the co-existence of angioedema.

How should the first episode be managed in primary care? Is the cause usually allergic – and if so, is the allergen usually easy to identify?

In spontaneous urticaria, treatment of the first episode with antihistamines is appropriate. Higher than normal doses of antihistamines may be required, for example cetirizine 10mg twice daily and maximally 20mg twice daily.1,2,3  Common triggers for episodes of chronic urticaria are stress and intercurrent viral infections.

Patients often analyse the foods they’ve eaten over the previous day or so, or washing powders they’ve used, in the search for a connection with symptoms, but these are not the cause. You can explain to patients that in genuine food allergy, symptoms usually occur reproducibly within minutes and maximally within 60 minutes of exposure to the offending food, and symptoms settle within 24 hours. So an urticarial rash persisting for days is not food related. A rash present on waking is not allergic in origin.

Also, a new food allergy occurring in an adult without a history of atopy – eczema, allergic rhinitis and asthma – or food allergy would be unusual. But if the patient is unconvinced, they can avoid the ‘offending’ food for a few days, and if the rash persists, this disproves the association.

In prolonged cases, what are the likely underlying causes and what investigations should be considered?

Some 30% of individuals with chronic spontaneous urticaria have autoimmune thyroid disease and so thyroid function should be measured. However, treating the hypothyroidism will not resolve the urticarial rash.

If the urticarial lesions stain or bruise, then urinalysis for blood and protein is indicated. If the urine test is positive, consider an urgent referral as a systemic vasculitis is a possibility. A blood test for anti-neutrophil cytoplasmic antibodies may be useful at this stage.

Individuals with chronic urticaria are typically busy, driven meticulous individuals. Discussion of lifestyle factors related to these stressors may be useful and such individuals may benefit from cognitive behavioural therapy. Psychiatric morbidity is high in this group of patients.4

In a patient taking long-term medication, is it likely that the urticaria is related to one of the drugs? Are ACE inhibitors a particular issue?

NSAIDs can be associated with urticaria but tend to cause acute severe symptoms and if they are being taken intermittently would not cause a continuous persistent urticarial rash. Codeine-related drugs also induce urticaria.

You should take care to distinguish urticaria from flushing – flushing is rarely itchy. Photographs can be helpful if the rash is evanescent. 

Angioedema occurs in less than half of cases of chronic urticaria. ACE inhibitors will aggravate the angioedema component and so an ARB is recommended instead. But chronic urticaria alone is not associated with or aggravated by antihypertensives, so in this case the ACE inhibitor – perindopril - does not need to be substituted.

What treatment should be offered in chronic urticaria? When might referral be considered?

Complete suppression of the urticarial rash is the goal of treatment and high doses of antihistamines may be required to achieve this. Cetirizine up to 20mg twice daily can be used and is superior to higher dose loratadine or desloratadine. Fexofenadine 180mg is the licensed dose for urticaria but may not give full 24-hour control.  

Treatment to achieve complete suppression of the rash for three to six months is recommended, followed by gentle tapering of dosage. I recommend CBT for some motivated patients with chronic spontaneous urticaria to facilitate lifestyle changes. 

This condition can, and should, be managed in primary care, and only those who fail on the above regime require referral. Some patients demand investigations to exclude perceived food allergies, but as discussed, this is unwarranted for most patients. Specific IgE testing (RAST) is rarely helpful and should be avoided. 

 

Professor Richard Powell is emeritus professor of clinical immunology and allergy at Nottingham University

The British Society for Allergy and Clinical Immunology (BSACI) is the professional and academic society representing the specialty of allergy at all levels. Its aim is to improve the management of allergies and related immune system diseases in the UK through education, training and research. Its website bsaci.org is being updated and will be launched shortly. Further resources and signposting to educational material will be added. You can find your nearest allergy clinic on the website, and allergy meetings for primary care - including a dedicated primary care day at the BSACI annual conference on 9 July 2013.

 

References and further reading

1 Powell RJ, Du Toit GL, Siddique N et al. BSACI guidelines for the management of chronic urticaria and angio-oedema. Clinical and Experimental Allergy 2007;37:631-50

2 Potter PC, Kapp A, Maurer M et al. Comparison of the Efficacy of levocetirizine 5mg and desloratadine 5mg in chronic idiopathic urticaria patients. Allergy 2009;64: 596-604

3 Meltzer EO and Gillman SA. Efficacy of fexofenadine versus desloratadine in suppressing histamine-induced wheal and flare. Allergy Asthma Proc 2007;28:67-73

4 Ozkan M, Oflaz SB, Kocaman N et al. Psychiatric morbidity and quality of life in patients with chronic idiopathic urticaria. Ann Allergy Asthma Immunol 2007; 99:29-33.

 

 

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