The natural history of exercise-induced anaphylaxis: Survey results from a10-year follow-up study

Background: Exercise-induced anaphylaxis (EIA) is a unique physical allergy that is triggered by exertion, the clinical spectrum and modifying factors of which have been previously studied. At the time of initial description, it was postulated that other factors contributed to this disorder. Objective: We sought to determine the clinical course and potential modifyi ng factors in EIA, Methods: In 1993, we conducted a cross-sectional analysis of 671 individual s with exercise-associated symptoms for more than a decade using a validate d 75-item questionnaire. Subjects met criteria for EIA if they had anaphyla ctic symptoms, including hypotension or upper airway obstruction, urticaria , or angioedema with physical exertion but without a passive increase in co re body temperature. Results: Of 365 (54%) questionnaire respondents, 279 (87%) met criteria for EIA (199 females and 80 males). At the time of study entry, subjects with EIA (mean age, 37.5 years; range, 13 to 77 years) had an average of 10.6 ye ars of symptoms, which were most frequently triggered by aerobic activities such as jogging or brisk walking (78% and 42%, respectively). On average, subjects reported that the frequency of attacks had decreased (47% of subje cts) or stabilized (46% of subjects) since onset. One hundred (41%) subject s reported being completely free of attacks in the past year. Subjects redu ced their attacks by avoiding exercise during extremely hot or cold weather (44%), avoiding ingestion of certain foods before exercise (37%), and rest ricting exercise during their allergy season (36%) or humid weather (33%). The most common pharmacologic agents used to manage symptoms were H1 antago nists (56%) and/or epinephrine (31%), However, 28% used no treatment at all . Conclusion: EIA is an episodic condition in which the frequency of attacks tends to stabilize or decrease over time. Improvement appears to result fro m individual modification of exercise and avoidance of known environmental and ingestible precipitants.