The clinical spectrum of anaphylaxis in north-west England

Objective To assess the clinical spectrum of anaphylaxis with a view to developing management guidelines and as a foundation for an epidemiological study. Methods Study of the reaction histories and investigations of 172 patients, including children and adults, referred because of anaphylactic reactions Results Over 700 reactions occurred in 172 patients from age 5 months to 69 years. There were equal numbers of males and females; when ranked by age at worst reaction, the youngest quartile (0-4 years) was 75% male and the oldest quartile (40+ years) was 74% female. The severity of reactions graded continuously from fatal to mild. One hundred and twenty of 172 had two or more reactions; the worst reaction was the first in 33, midsequence in 35 and the most recent in 52. Suspected causes of each patient's worst reaction associated with positive allergy tests include peanuts (42), tree nuts (23), other foods (25, in five associated with exercise), venoms (six bee, 22 wasp), muscle relaxants (seven) and latex (six). Twenty were classified as idiopathic and, in a further 13, investigation of the suspected cause proved negative. There was doubt about the nature of some of the 'reactions' reported even though these had been treated as for anaphylactic reactions. Conclusion The clinical spectrum of anaphylaxis has been defined for the area served by our unit. Management guidelines and future epidemiological studies will have to address the continuous distribution of severity of reactions, the wide age range and the multiplicity of causes.