Why accurate history taking is essential in allergic rhinitis
The term 'rhinitis' implies an inflammatory response of the lining membrane of the nose. Rhinitis is a significant cause of widespread morbidity, medical treatment costs, reduced work productivity and lost school days. Although frequently mistakenly viewed as a trivial disease, the condition may have a significant impact on patients' quality of life.
Rhinitis most commonly has an allergic basis, although it may also be caused by infectious, hormonal, occupational and other factors. Diagnosing the correct aetiology of rhinitis is important because the various causes may require different therapeutic approaches for optimal management.
Allergic rhinitis relates to the immediate immunoglobulin (IgE) antibody-mediated hypersensitivity reaction to specific allergens, a type 1 hypersensitivity reaction.1 Nasal obstruction and watery rhinorrhoea are characteristic symptoms of allergic rhinitis. Patients frequently experience itching and sneezing when directly exposed to allergens.
Seasonal allergic rhinitis affects 26-29% of the population.2 The most common allergens are grass, pollen, weeds and flowers. The house dust mite, animal dander, household dust and feather are the principal allergens in perennial allergic rhinitis.
The diagnosis is primarily established by taking a detailed history and performing an ENT examination, including nasal endoscopy in the rhinology clinic setting to exclude other nasal pathology.3 It is important to realise that there is no gold standard test for the diagnosis of allergy, and although allergen testing can support a diagnosis based on a clinical history it can never be used alone.4
Skin-prick testing provides a fast, safe and relatively cheap objective means of assessing allergy, but this technique is not without drawbacks. Certain drugs (e.g. phenothiazines, and antihistamines) affect the results, and patients with seasonal rhinitis may also show a seasonal skin-prick response.5 Serological testing for IgE is frequently used as an adjunct to skin-prick testing for the diagnosis of allergy.6
Measurement of total serum IgE levels can also be misleading as there is a considerable normal range in adults. Many patients with allergic rhinitis will have normal total IgE levels, but will have raised levels of specific IgE to one or more allergens.7 Total IgE can also be raised in myocardial infarction and surgical procedures.8
Nasal challenge testing using inhaled allergens is the most direct method of identifying allergic rhinitis, although this is impracticable for routine clinic use and is essentially a research tool.
In our rhinology clinic it is routine practice to perform skin allergy testing alone, accepting that rarely patients can have negative tests despite a good history of rhinitis relating to a specific allergen.
Many patients present to their GP with rhinitis. Although an allergic basis is common, other aetiologies must be considered and accurate history taking is paramount. Allergy testing can be used to confirm the diagnosis.
- See also 'Managing allergic rhinitis in primary care' in this issue.
- International Rhinitis Management Working Group. International consensus report on the diagnosis and management of rhinitis. Allergy 1994; 49 (Suppl 19): 5-34.
- Coca AF, Cooke RA. On the classification of the phenomena of hypersensitivities. J Immunol 1923; 8: 163-82.
- Aberg N, Hessel B, Aberg B, Eriksson B. Increase of asthma, allergic rhinitis and eczema in Swedish schoolchildren between 1979 and 1991. Clin Exp Allergy 1995; 25: 815-19.
- Maclennan A, McGarry OW. Diagnosis and management of chronic sinusitis. Br Med J 1995; 310: 529.
- Dreborg S, Frew A. Position paper: allergen standardization and skin test. Allergy 1993; 48 (Suppl): 49-82.
- Johansson SG. Discovery and development of IgE assays. Clin Exp Allergy 1997;27(Suppl):60-3.
- Droste JA, Kerhof M, Schousten J. Association of skin test reactivity, specific IgE, total IgE and eosinophils with nasal septum in community-based population study. J Allergy Clin Immunol 1996; 97: 922-32.
- Szcekik A, Jaiwien J. IgE in acute phase response to surgical stress. Clin Exp Allergy 1996; 26: 303-7.