The etiology, risk factors, and clinical features of anaphylaxis: The single-center retrospective cohort study of the tertiary university hospital
Authors: Tunakan Dalgıç Ceyda 
Published: August 2023

Background/Aim: Anaphylaxis presents in multiple ways, making its diagnosis challenging. Delayed diagnosis can lead to a postponement in administering crucial adrenaline treatment. The prevalence of anaphylaxis varies by geographical region and gender. However, there has been no comprehensive regional analysis of anaphylaxis data within our country. Despite an increasing incidence, our understanding of anaphylaxis etiology, risk factors, and clinical features remains limited, particularly within our nation. This study aims to assess the frequency, etiology, risk factors, and clinical findings of anaphylaxis among patients seen at the allergy clinic of a tertiary university hospital. Additionally, it seeks to compare regional data with existing literature.
Methods: This retrospective cohort study reviewed the medical records of 8,295 patients who visited the allergy outpatient clinic at Sivas Cumhuriyet University Hospital between July 2, 2018, and December 10, 2019. The hospital’s data system retrospectively analyzed records using the ICD code T78.2 (anaphylaxis). Only cases where patients were prescribed an adrenaline auto-injector were included. The study evaluated anaphylaxis frequency, etiologies, demographics, and clinical features.
Results: The study identified 77 patients (n=77) with a mean age of 40.29 (3.77) years, consisting of 47 females and 30 males. The frequency of anaphylaxis among allergy outpatient admissions was less than 1% (0.009%). Single-type atopic diseases included venom allergy (23%), drug allergy (14%), inhalant allergens (n=6), food allergens (n=4), and skin allergic diseases (n=3). Multiple allergic diseases were present in 40% (n=31) of cases. Prick tests were performed on 56 (72%) patients, with 25 (44%) yielding negative results. Among positive prick test cases, venom was the main cause of anaphylaxis (82%), while drug allergy was more prevalent (68.2%) among negative test results (P=0.016). Inhalant allergen sensitivity and allergen polisensitivity did not significantly influence the anaphylaxis cause (P<0.001). Causes of anaphylaxis included drug allergy (47%), venom allergy (31%), food allergens (16%), food-dependent exercise-induced reactions (n=2), idiopathic cases (n=2), and cold urticaria (n=1). Non-steroidal anti-inflammatory drugs (NSAIDs) (44%) and beta-lactams (10%) were the primary culprits. In cases where neither drugs nor venom were involved, food allergies were the cause (P<0.001). With venom allergy, the cause was venom, and without venom, drug allergy was the cause (P<0.001). Female patients showed significantly higher drug- and food-related anaphylaxis rates than males (P=0.032 and P=0.042, respectively). History of Apis mellifera-related anaphylaxis was significantly more common than Vespula vulgaris-related cases (P=0.028). Anaphylaxis severity included grade 2 (30%), grade 3 (48%), and grade 4 (12%) reactions. Recurrent anaphylaxis episodes occurred in 55% (n=42) of patients. Initial hospital administrations involved epinephrine injections in only 25% (n=19) of cases. Cutaneous symptoms were present in 94%, respiratory symptoms in 88%, cardiovascular symptoms in 63%, neurological symptoms in 57%, and gastrointestinal symptoms in 12% of patients.
Conclusion: This study identified drug allergy as the leading cause of anaphylaxis in the examined cases. Preventable factors contributing to drug-induced anaphylaxis included insufficient patient and physician knowledge and widespread over-the-counter drug use without medical consultation. Despite 55% of patients experiencing recurrent attacks, only a quarter received epinephrine administration. These findings emphasize the need to educate patients with recurrent anaphylaxis about avoidance strategies and to enhance healthcare providers’ understanding of anaphylaxis treatment.