Mullins RJ. Clin Exp Allergy. 2003;33:1033–1040
Purpose of the Study.
To determine the incidence of anaphylaxis and risk factors for recurrence.
Four hundred thirty-two patients with anaphylaxis who were referred to a community-based specialist practice in the Australian Capital Territory were studied. Twenty-seven percent were of school age (5–18 years of age).
Patients referred to an allergist for evaluation of anaphylaxis were enrolled during a 5.5-year period and evaluated prospectively. Medical record review, patient questionnaires, allergy skin testing, and challenge testing (for a small subset of patients) were used.
Of 432 patients (48% male, 73% atopic; mean age: 27.4 years; SD: 19.5 years; median: 26 years) with anaphylaxis, 260 patients were examined after the first episode; 172 experienced 584 previous reactions. Fifty-four percent of index episodes were treated in a hospital. Causes were identified for 91.6% patients, ie, food (61%), stinging insects (20.4%), or medication (8.3%). The minimal occurrence and incidence of new cases of anaphylaxis were estimated as 12.6 and 9.9 episodes/100 000 patient-years, respectively. Follow-up data were obtained for 304 patients (674 patient-years). One hundred thirty experienced additional symptoms (45 serious), 35 required hospitalization, and 19 were administered epinephrine. Accidental ingestion of peanuts or tree nuts caused the largest number of relapses, but the highest risk of recurrence was associated with sensitivity to wheat and/or exercise. Rates of overall and serious recurrence were 57 and 10 episodes/100 patient-years, respectively. Among patients prescribed epinephrine, three-fourths of the patients carried it, two-thirds of the doses were in date, and only one-half of the patients faced with serious symptoms administered epinephrine. Five patients developed new triggers for anaphylaxis.
In any 1 year, 1 of 12 patients who have suffered anaphylaxis will experience recurrence and 1 of 50 will require hospital treatment or will use epinephrine. Compliance with carrying and using epinephrine is poor. Patients occasionally develop new triggers.
There are few studies on the incidence or recurrence of anaphylaxis, but the limited data suggest that the incidences of anaphylaxis and food allergy are increasing. In this study, allergic reactions to peanuts and tree nuts were the most common cause of anaphylaxis and the most common reason for recurrence, but other foods, such as eggs, fruits, vegetables, wheat, fish, and shellfish, were also common triggers. Compliance with the use of self-injectable epinephrine was only 50%. Because of the high risk of recurrence, each anaphylactic event should be reviewed and patients should be reeducated regarding trigger avoidance, recognition of symptoms, and use of epinephrine.