Emergency Treatment and Prevention of Insect-Sting Anaphylaxis
Emergency Treatment and Prevention of Insect-Sting Anaphylaxis
Purpose of Review: Hymenoptera stings are thought to cause systemic allergic reactions in 0.4-5% of individuals, and to account for 40-100 deaths annually in the USA. This review examines current research on insect-sting anaphylaxis in the emergency department (ED), and provides suggestions on how to improve ED treatment and prevention.
Recent Findings: Few published studies since January 2005 examine the emergency management of insect-sting allergic reactions. Earlier studies found that few ED patients with this problem received health education, a prescription for self-injectable epinephrine or referral to an allergy specialist at ED discharge. A recent multicenter study by our group demonstrated that ED patients with insect-sting allergic reactions continue to receive care discordant with national guidelines for the emergency management of anaphylaxis.
Summary: Concordance with national guidelines for the treatment of anaphylaxis remains poor among insect-sting allergy patients. The development of a simple, clinical definition of anaphylaxis is urgently needed to facilitate identification of cases. Such a definition would help tremendously with dissemination of emergency management guidelines and the creation of systems for their implementation. All of these steps are essential for the improved treatment and prevention of insect-sting anaphylaxis in the ED.
The lifetime prevalence of anaphylaxis in Westernized countries has been very difficult to determine. A literature review by Neugut and colleagues estimated the US incidence of anaphylaxis to be anywhere between 1 and 15%. By contrast, a population-based study in Olmsted County, Minnesota, by Yocum and colleagues concluded that the prevalence of anaphylaxis was less than 1%. A review of recent studies from the USA, Canada and the UK yields prevalence estimates ranging from 0.3-0.6 to 0.95%.
Many of these allergic reactions are managed in the emergency department (ED). For example, a managed care study from Washington State estimated that 71% of all anaphylaxis reactions in a healthcare system were seen in the ED. Nevertheless, the prevalence of anaphylaxis among all ED visits is less than 1%, or approximately 400 000 visits/year (unpublished data). Among this relatively large group of ED patients, anywhere from 1.4 to 59% of acute allergic reactions are due to insect stings. This uncertainty is not surprising given the diverse estimates of the percentage of all anaphylaxis due to insect stings - regardless of clinical setting. For example, Hymenoptera stings (e.g. fire ants, wasps, yellow jackets and hornets) are thought to have caused anaphylaxis, at some point, in 0.4-5% of the general population. Other studies report that systemic allergic reactions to Hymenoptera venom occur in 0.4-3.3% of individuals. Looking beyond lifetime prevalence and percentage of ED visits, vital statistics suggest that approximately 40-100 Americans die every year as a result of insect stings. Even these numbers are thought to be inaccurate, however, with most experts convinced that they are gross underestimates.
Regardless of the exact numbers, patients continue to visit EDs for management of insect-sting-related allergic reactions. Timely and appropriate treatment is necessary to prevent progression of the allergic reaction. Moreover, there is a growing emphasis on education and preventive measures, as individuals with a history of anaphylaxis are at an increased risk of a subsequent episode. To that end, national guidelines recommend treatment of all severe allergic and anaphylactic reactions with epinephrine, teaching of proper techniques for self-injectable epinephrine and referral to an allergist for further care.
A prompt and accurate diagnosis identifies those at greatest risk for adverse outcomes. An accurate diagnosis is, of course, essential for effective emergency management. Given such large variability in current anaphylaxis estimates in the general population and in the ED - and studies suggesting that the prevalence of allergies is rising - there truly is an urgent need to develop clinical definitions that assist in diagnosis. Such a tool would allow better measurement of the actual prevalence of all types of anaphylaxis and promote improved ED treatment. Correct patient identification also could be used to target prevention efforts among those individuals at highest risk of a recurrent insect sting.
This article reviews the sparse literature on the treatment and prevention of insect-sting related anaphylaxis in the ED. Additionally, we suggest steps that can be taken to improve the identification and overall management of this condition in the ED setting.
Abstract and Introduction
Abstract
Purpose of Review: Hymenoptera stings are thought to cause systemic allergic reactions in 0.4-5% of individuals, and to account for 40-100 deaths annually in the USA. This review examines current research on insect-sting anaphylaxis in the emergency department (ED), and provides suggestions on how to improve ED treatment and prevention.
Recent Findings: Few published studies since January 2005 examine the emergency management of insect-sting allergic reactions. Earlier studies found that few ED patients with this problem received health education, a prescription for self-injectable epinephrine or referral to an allergy specialist at ED discharge. A recent multicenter study by our group demonstrated that ED patients with insect-sting allergic reactions continue to receive care discordant with national guidelines for the emergency management of anaphylaxis.
Summary: Concordance with national guidelines for the treatment of anaphylaxis remains poor among insect-sting allergy patients. The development of a simple, clinical definition of anaphylaxis is urgently needed to facilitate identification of cases. Such a definition would help tremendously with dissemination of emergency management guidelines and the creation of systems for their implementation. All of these steps are essential for the improved treatment and prevention of insect-sting anaphylaxis in the ED.
Introduction
The lifetime prevalence of anaphylaxis in Westernized countries has been very difficult to determine. A literature review by Neugut and colleagues estimated the US incidence of anaphylaxis to be anywhere between 1 and 15%. By contrast, a population-based study in Olmsted County, Minnesota, by Yocum and colleagues concluded that the prevalence of anaphylaxis was less than 1%. A review of recent studies from the USA, Canada and the UK yields prevalence estimates ranging from 0.3-0.6 to 0.95%.
Many of these allergic reactions are managed in the emergency department (ED). For example, a managed care study from Washington State estimated that 71% of all anaphylaxis reactions in a healthcare system were seen in the ED. Nevertheless, the prevalence of anaphylaxis among all ED visits is less than 1%, or approximately 400 000 visits/year (unpublished data). Among this relatively large group of ED patients, anywhere from 1.4 to 59% of acute allergic reactions are due to insect stings. This uncertainty is not surprising given the diverse estimates of the percentage of all anaphylaxis due to insect stings - regardless of clinical setting. For example, Hymenoptera stings (e.g. fire ants, wasps, yellow jackets and hornets) are thought to have caused anaphylaxis, at some point, in 0.4-5% of the general population. Other studies report that systemic allergic reactions to Hymenoptera venom occur in 0.4-3.3% of individuals. Looking beyond lifetime prevalence and percentage of ED visits, vital statistics suggest that approximately 40-100 Americans die every year as a result of insect stings. Even these numbers are thought to be inaccurate, however, with most experts convinced that they are gross underestimates.
Regardless of the exact numbers, patients continue to visit EDs for management of insect-sting-related allergic reactions. Timely and appropriate treatment is necessary to prevent progression of the allergic reaction. Moreover, there is a growing emphasis on education and preventive measures, as individuals with a history of anaphylaxis are at an increased risk of a subsequent episode. To that end, national guidelines recommend treatment of all severe allergic and anaphylactic reactions with epinephrine, teaching of proper techniques for self-injectable epinephrine and referral to an allergist for further care.
A prompt and accurate diagnosis identifies those at greatest risk for adverse outcomes. An accurate diagnosis is, of course, essential for effective emergency management. Given such large variability in current anaphylaxis estimates in the general population and in the ED - and studies suggesting that the prevalence of allergies is rising - there truly is an urgent need to develop clinical definitions that assist in diagnosis. Such a tool would allow better measurement of the actual prevalence of all types of anaphylaxis and promote improved ED treatment. Correct patient identification also could be used to target prevention efforts among those individuals at highest risk of a recurrent insect sting.
This article reviews the sparse literature on the treatment and prevention of insect-sting related anaphylaxis in the ED. Additionally, we suggest steps that can be taken to improve the identification and overall management of this condition in the ED setting.
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