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August 29, 2016

Anaphylaxis episodes and anaphylaxis deaths

Anaphylaxis episodes and anaphylaxis deaths

Question

There is discordance between anaphylaxis episodes (increasing markedly) and anaphylaxis deaths (remaining stable) in developed countries, at least in Australia where good figures are available. What is the explanation?

Answers

From the Editor: Our experts discuss the discordance of rising number of anaphylaxis cases but stable deaths, the latter observation possibly indicating improved recognition and early treatment.  

 

By Dr Andrea Vereda-Ortiz

This is a very interesting question, and honestly, I don’t have a straightforward answer.

There is, indeed, a nice Australian paper 1, which demonstrates an increase on anaphylaxis admissions between 1997 and 2005 for both food and drug-induced anaphylaxis. In this study, the food-induced death rates did not increase, however, the drug-induced anaphylaxis deaths did increase (drug-induced anaphylaxis deaths doubled the increase in drug-induced anaphylaxis hospital admissions) 1.

The reasons why the anaphylaxis admissions have increased while the deaths have not (in general, without etiology classification) are not are not clearly known. Maybe the admissions increase is linked with a better awareness of the condition by the general public.  And perhaps the death rates have remained stable because the anaphylaxis management has improved (prescription for adrenaline auto-injectors has increased in some countries 1, 2). However, these are only my personal opinions since no clear data are available in the literature.

  1. Liew WK, Williamson E, Tang ML. Anaphylaxis fatalities and admissions in Australia. J Allergy Clin Immunol 2009;123:434-42
  2. Sheikh A, Hippisley-Cox J, Newton J, Fenty J. Trends in national incidence, lifetime prevalence and adrenaline prescribing for anaphylaxis in England. J R Soc Med 2008;101:139-43

Andrea Vereda-Ortiz
Allergology Department
Hospital Infantil Universitario Niño Jesus
Madrid Spain

 

By Dr Carlos Camargo

The epidemiology of anaphylaxis has challenged researchers for decades because of two related issues: the ambiguous case definition (1) and the many types of anaphylaxis events – e.g., an unreported event outside clinical setting versus events associated with an office visit, emergency department visit, hospitalization, or death.  The field advanced significantly in the mid-2000s when a multidisciplinary group created a standard definition of when clinicians should consider the diagnosis of anaphylaxis (2). Widespread adoption of this definition (3) has undoubtedly improved the quality of anaphylaxis surveillance.

As the reader points out, recent surveillance has revealed a rise in at least some types of non-fatal anaphylaxis, but no corresponding rise in fatal anaphylaxis. The observed increase has several possible explanations, but it likely reflects the steady increase in the population prevalence of allergies, especially food allergy. In other words, if there are more people with peanut allergy, there probably will be more peanut-related anaphylaxis events. Some portion of the rising prevalence is due to greater recognition and diagnosis, but the increases are so large that it’s probably a mix of greater detection and actual increases in food allergy. Either way, it’s reassuring that anaphylaxis deaths have remained stable since a higher prevalence of allergy, with more anaphylaxis events, also should - all other things being equal - lead to more anaphylaxis deaths. The discordance suggests to me that more timely recognition and treatment of anaphylaxis is saving lives. While much work remains to be done, the observed discordance probably represents a little “good news” regarding the allergy epidemic.

 

REFERENCES

1. Camargo CA Jr. Potter Stewart and the definition of anaphylaxis. J Allergy Clin Immunol 2012; 129: 753-754. PMID: 22285277

2. Sampson HA, Munoz-Furlong A, Campbell R, Adkinson NF Jr, Bock SA, Branum A, Brown S, Camargo CA Jr, Cydulka R, Galli SJ, Gidudu J, Gruchalla RS, Harlor AD Jr, Hepner DL, Lewis LM, Lieberman PL, Metcalfe DD, O’Connor R, Plaut M, Muraro A, Rudman A, Schmitt C, Scherrer D, Simons FE, Thomas S, Wood JP, Decker WW. Second symposium on the definition and management of anaphylaxis: Summary report. J Allergy Clin Immunol 2006; 117: 391-397. PMID: 16461139

3. Boyce JA, Assa'ad A, Burks AW, Jones SM, Sampson HA, Wood RA, Plaut M, Cooper SF, Fenton MJ, Arshad SH, Bahna SL, Beck LA, Byrd-Bredbenner C, Camargo CA Jr, Eichenfield L, Furuta GT, Hanifin JM, Jones C, Kraft M, Levy BD, Lieberman P, Luccioli S, McCall KM, Schneider LC, Simon RA, Simons FE, Teach SJ, Yawn BP, Schwaninger JM. Guidelines for the diagnosis and management of food allergy in the United States: Report of the NIAID-sponsored Expert Panel Report. J Allergy Clin Immunol 2010; 126 (6 suppl): S1-58. PMID: 21134576  

Carlos Arturo Camargo Jr., MD, DrPH
Physician, Department of Emergency Medicine
Massachusetts General Hospital
Professor, Medicine and Epidemiology at Harvard Medical School
Boston, Massachusetts, USA


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