Anaphylaxis in primary care: Systematic review to support quality of management and optimization of health-care pathways

Abstract

Anaphylaxis is a severe, life-threatening systemic hypersensitivity reaction characterized by rapid onset and the potential to endanger life. Most of cases of anaphylaxis are first seen by general practitioners (GPs) or emergency doctors. This systematic review is intended to provide evidence-based decision support tools to GPs confronted with anaphylactic patients. We searched MEDLINE, EMBASE, Cochrane Controlled Register of Trials, Lilacs databases from inception from 1988, for manuscripts concerning anaphylaxis and primary care, without language restrictions. We screened studies, extracted data, and assessed risk of bias independently in duplicate. The manual review was performed by two independent ratters. The degree of inter-rater agreement was assessed using Cohen’s kappa. Main outcomes included clinical history, clinical examination, treatment, use of epinephrine and timing to refer the patient to the specialist. We selected 56 studies, comprising 37 original articles, 15 reviews and 4 guidelines. Twenty-three (41%) were focused on specific aetiology: food-induced anaphylaxis (FA) (52%), drug allergy (DA) (35%) and venom allergy (VA) (13%). With a kappa value of 0.67, there was a high agreement on the classification procedures between the two raters. Data showed that in the presence of respiratory and/or cardiovascular symptoms, patients should be promptly treated and sent to the emergency room. Structured clinical history was reported as being mandatory for the diagnosis of anaphylaxis, mainly based on 5 key points: type of manifestations, type of trigger, chronology between reaction and suspected allergen, reproducibility and risk factors. Most documents (44%) covered food-induced anaphylaxis occurring in childhood, with suspected IgE-mediated reaction. Most anaphylaxis in adults were related to DA or VA (48%). Data still stress lack of the recognition of manifestations (48%), treatment with anti-histamines and systemic corticosteroids (26%), delayed application of epinephrine (35%) and highlight the need of decision aids to support diagnosis and anaphylaxis by GPs (38%). GPs should advise an emergency plan and prescribe adrenaline auto-injectors. Reasons for referring to specialists based on the literature are: to investigate aetiology, to undergo specific treatment, such as allergen immunotherapy, severe cases or in suspicion of underlying condition, such as mastocytosis. Evidence presented supports the construction of a decision tree in order to improve management of anaphylaxis. This intends to optimize the life-time of these patients across the health care pathways and prevent avoidable deaths. It is intended that the resultant decision support tool will undergo field-testing for validation.