According to Cleveland Clinic researchers, the incidence of anaphylaxis may be increasing, with idiopathic anaphylaxis being the most common. At the annual meeting of the American Academy of Allergy, Asthma and Immunology in New Orleans they presented the results of their investigation into the pattern of anaphylaxis at their tertiary care referral center. Under an IRB-approved protocol, they searched the electronic medical records from July 2002 to July 2009 for patients with ICD-9 codes consistent with anaphylaxis (995.0, 995.6x, 989.82, 989.5, 202.6, 995.20, and 995.27). Of 1546 cases identified, 450 were randomly selected by medical record number. Records were examined for cause and symptoms of anaphylaxis, age, gender, history of atopy, and whether epinephrine was prescribed. Reactions involving two or more organ systems were classified as anaphylaxis. Of the 450 cases reviewed, 225 met the study protocol's definition of anaphylaxis. Those excluded primarily had isolated urticaria and/or angioedema with food ingestion. The mean age of the patients was 24.2; 46.2% were female, 83.6% were Caucasian. Food was the most common cause (45.3%) of the anaphylaxis, followed by venom (24.4%), and drugs (6.2%). The percentage of idiopathic cases was 13.8. Among the foods causing reactions, the most common were peanuts (27.5%) and tree nuts (21.6%). The most frequent symptoms were urticaria and/or angioedema (88.4%), shortness of breath and/or cough (67.1%), and laryngeal involvement (36.4%). History of atopy was present in 62.7%. Epinephrine was prescribed in 89.3%. The Cleveland Clinic researchers noted that a substantial proportion of patients with codes consistent with anaphylaxis did not have anaphylaxis upon review of the medical record. But epinephrine was prescribed appropriately in almost all cases.