Peng MM, Jick H. Arch Intern Med. 2004;164:317–319
Purpose of the Study.
To determine the incidence, severity, and causes of anaphylaxis in the United Kingdom.
United Kingdom residents born between 1912 and 1999 who were registered in the General Practice Research Database between 1994 and 1999.
The General Practice Research Database includes demographic and clinical data provided by general practitioners in the United Kingdom. Inclusion criteria for this study were an age of <80 years and having at least 6 months of recorded data in the database. After all cases were identified, 70 cases were selected randomly to undergo a more detailed evaluation that included contacting the general practitioner involved in the case. The investigators defined anaphylaxis as an acute allergic reaction characterized by generalized urticaria, often accompanied by swollen tongue, wheezing, flushing, gastrointestinal symptoms, or hypotension. The reaction was considered mild if the symptoms were primarily limited to generalized urticaria and did not require treatment in an emergency department; the reaction was considered to be moderate if a hospital or emergency department visit was initiated for treatment and the symptoms were treated with epinephrine; and the event was considered to be severe if there was hypotension.
A total of 898 patients were identified, and a random sample of 70 (9%) cases with a coded diagnosis and 50 (43%) cases with a comment diagnosis underwent additional evaluation. Relevant information on the diagnosis was available for >90% of these cases. Criteria for anaphylaxis was met in 87 of the 120 cases, so that an estimated 675 cases of the total 783 were estimated to have confirmed anaphylaxis, resulting in an incidence of 8.4 cases per 100 000 person-years. Insect stings were responsible for 32% and medications for 30% of cases. Food was implicated in 22% of cases, and more than half of these were due to a tree nut or peanut. Severity of the cases was as follows: mild, 29%; moderate, 45%; severe, 9%; indeterminate, 17%. One death was identified.
In the United Kingdom, the estimated incidence rate of anaphylaxis was 8.4 cases per 100 000 person-years, and ∼10% of these cases were life threatening.
Although anaphylaxis is a relatively uncommon event, 10% of cases are characterized by hypotension. The estimated percentage of severe, life-threatening events would have been even higher if lower-airway symptoms were considered as a manifestation of severe anaphylaxis. Physicians evaluating patients with suspected allergic reactions should be prepared to treat life-threatening symptoms.