Anaphylaxis is an acute, life-threating condition that typically requires an ED visit, a prescription for medication, and physician follow-up. However, data regarding the prevalence of anaphylaxis in the United States are limited and vary widely. To help shed light on the state of anaphylaxis, Robert A. Wood, MD, and colleagues conducted random telephone surveys among the general U.S. adult population between July and November 2011. Results were published in the Journal of Allergy and Clinical Immunology.
Using a stringent definition, the research team found that 1.6% of survey respondents “very likely” had anaphylaxis and that 5.1% had “probable” anaphylaxis. “Anaphylaxis is clearly a common condition, perhaps more than what has been estimated in prior surveys,” says Dr. Wood. “Furthermore, anaphylaxis is common among all age groups. It has been previously thought to be a pediatric problem, but our surveys focused entirely on adults. Healthcare providers will encounter anaphylaxis on a regular basis, and therefore should be inquiring about it while taking initial or integral medical histories.”
Key Findings
Beyond determining the prevalence of anaphylaxis, the researchers sought to gather information on the symptoms and triggers of anaphylactic reactions as well as how patients reacted to episodes in terms of accessing healthcare and using medications. After conducting a survey of the general population (public survey), a second survey was conducted targeting a higher-risk population of subjects with a history of allergic reactions (patient survey).
“The symptoms typically thought to accompany anaphylaxis, such as skin reactions and respiratory issues, were indeed the most common among both groups,” says Dr. Wood (Figure). “Other common symptoms involved the gastrointestinal, cardiovascular, and neurologic systems. Neurologic symptoms were common and more prevalent in the patient survey than the public survey. The patient survey sample size was considerably larger, so those numbers are likely more reliable.”Dr. Wood and colleagues defined “confirmed anaphylaxis” as involving at least two systems, including the respiratory and/or cardiovascular systems, and/or loss of consciousness, even as a lone symptom. This was done in order to distinguish these patients from those with reported anaphylaxis. “It’s somewhat reassuring that our findings for both groups match up almost identically,” Dr. Wood says (Table). “The majority of patients had more than one anaphylactic episode, and a large subset—about 19%—had a least five prior episodes.”
“Even when patients are careful to avoid certain foods, accidental exposures can occur.”
Findings on how anaphylaxis and anaphylactic reactions were dealt with by patients were less reassuring and raised concern over how appropriately reactions were being treated and the readiness of patients to manage these issues in the future. “The best gauge for determining patient readiness for dealing with anaphylaxis is if they’ve been prescribed self-injectable epinephrine, the mainstay of medical treatment for anaphylactic reactions,” Dr. Wood says. “Surprisingly, even in those with a history of repeat reactions, it was common for patients to not have an epinephrine prescription. If they did, they oftentimes did not use it in the event of a reaction.” Only 11% of respondents who experienced anaphylaxis had used epinephrine, and only 10% called 9-1-1. Of those who did call 9-1-1, more than 6% received no treatment and 52% did not receive a prescription for an epinephrine auto-injector.
Education Needed
According to Dr. Wood, physicians need to ensure that those with a history of anaphylaxis have self-injectable epinephrine available and a clear plan of how it and other medications should be used in the event of future reactions. “As their caretakers,” he says, “we need to help them identify reaction triggers and learn how to avoid these triggers whenever possible.” To obtain additional information, patients with anaphylaxis can be directed toward online educational materials or via referral to a specialist who can perform additional testing to better identify reaction triggers.
Some triggers are more avoidable than others, and most patients with specific drug allergies can recognize when they should avoid particular medications. On the other hand, it can be difficult for those with food allergies to consistently avoid the foods to which they are allergic. “Even when patients are careful to avoid certain foods, accidental exposures can occur, especially with common foods like milk, eggs, and peanuts,” Dr. Wood says. “The third most common trigger is stinging insects, and there are no ways for patients to prevent exposures to these unless they lock themselves indoors. Therefore, the key to patient education is to teach them how to be prepared to treat reactions when triggers are unavoidable.”
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