Severe
anaphylaxis is a systemic reaction affecting two or more organs or systems and is due to the release of active mediators from mast cells and basophils. A four-grade classification routinely places 'severe'
anaphylaxis in grades 3 and 4 (death could be graded as grade 5). Studies are underway to determine the prevalence of severe and lethal
anaphylaxis in different populations and the relative frequencies of food,
drug,
latex and Hymenoptera
anaphylaxis. These studies will also analyse the risk arising from the lack of preventive measures applied in schools (personalized management protocols) and from the insufficient use of self-injected adrenalin.
Allergy-related conditions may account for 0.2-1% of emergency consultations. Severe
anaphylaxis affects 1-3 per 10 000 people, but for the United States and Australia figures are even higher. It is estimated to cause death in 0.65-2% of patients, i.e. 1-3 per million people. An increased prevalence has been revealed by monitoring hospitalized populations by reference to the international classification of disease (ICD) codes. The relative frequency of aetiological factors of
allergy (food, drugs, insects and
latex) varies in different studies. Food,
drug and Hymenoptera
allergies are potentially lethal. The risk of food-mediated
anaphylaxis can be assessed from the number of personalized management protocols in French schools: 0.065%. Another means of assessment may be the rate of adrenalin prescriptions. However, an overestimation of the
anaphylaxis risk may result from this method (0.95% of Canadian children). Data from the literature leads to several possibilities. First, a definition of severe
anaphylaxis should be agreed. Secondly, prospective, multicentre enquiries, using ICD codes, should be implemented. Moreover, the high number of
anaphylaxis cases for which the aetiology is not identified, and the variation in aetiology in the published series, indicate that a closer cooperation between emergency specialists and allergists is essential.