ABSTRACT
Definitions Anaphylaxis is not a reportable disease and both its morbidity and mortality are probably underestimated. A variety of statistics on the epidemiology of anaphylaxis are published (Table 1) (1-10). There is no universally accepted clinical definition of anaphylaxis (11,12). The traditional nomenclature for anaphylaxis reserves the term anaphylactic for IgE-dependent reactions and the term anaphylactoid for IgE-independent events, which are clinically indistinguishable. The World Allergy Organization, which is an international umbrella organization whose members represent 74 national and regional professional societies dedicated to allergy and clinical immunology, recommends the replacement of this terminology with immunologic (IgE mediated and non-IgE mediated, e.g., IgG and immune complex complement mediated) and nonimmunologic anaphylaxis and the term “anaphylaxis” refers to both (11). Anaphylaxis was defined by the National Institute of Allergy and Infectious Diseases and Food Allergy and Anaphylaxis Network (Chantilly, Virginia, U.S.). It is considered likely to be present if any one of three criteria is satisfied within minutes to hours: (i) acute onset of illness with involvement of skin, mucosal surface, or both, and at least one of the following: respiratory compromise, hypotension, or end organ dysfunction; (ii) two or more of the following occur rapidly after exposure to a likely allergen: involvement of skin or mucosal surface, respiratory compromise, hypotension, or persistent gastrointestinal symptoms; (iii) hypotension develops after exposure to a known allergen for that patient: age-specific low blood pressure or decline of systolic blood pressure of greater than 30% compared to baseline (12). In clinical practice, however, waiting until the development of multiorgan symptoms is risky since the ultimate severity of an anaphylactic reaction is difficult to predict from the outset.
