Background: Fatal anaphylaxis is very rare, with an incidence ranging from 0.5 to 1 deaths per million person-years. Objective: Based on a systematic review, we aimed to explain differences in the reported incidence of fatal anaphylaxis based on the methodological and demographic factors addressed in the various studies. Methods: We searched PubMed/MEDLINE, EMBASE, and the Web of Science for relevant retrospective and prospective cohort studies and registry studies that had assessed the anaphylaxis death rate for the population of a country or for an administrative region. The research strategy was based on combining “anaphylaxis” with “death”, “study design”, and “main outcomes” (incidence). Results: A total of 46 studies met the study criteria and included 16,541 deaths. The range of the anaphylaxis mortality rate for all causes of anaphylaxis was 0.002-2.51 deaths per million person-years. Fatal anaphylaxis due to food (range 0.002-0.29) was rarer than deaths due to drugs (range 0.004-0.56) or Hymenoptera venom (range 0.02-0.61). The frequency of deaths due to anaphylaxis by drugs increased during the study period (IRR per year, 1.02, 95%CI 1.00-1.04). We detected considerable heterogeneity in almost all of the meta-analyses carried out. Conclusion: The incidence of fatal anaphylaxis is very low and differs according to the various subgroups analyzed. The studies were very heterogeneous. Fatal anaphylaxis due to food seems to be less common than fatal anaphylaxis due to drugs or Hymenoptera venom.
This article has been accepted for publication and undergone full peer review but has not been through the copyediting, typesetting, pagination and proofreading process, which may lead to differences between this version and the Version of Record. Please cite this article as
To the Editor, Some patients with anaphylaxis experience recurrences even when a trigger is identified in the initial reaction. [1][2][3][4][5][6] However, recurrence has received less attention than other epidemiological parameters associated with this condition. [1][2][3][4][5][6] We carried out a systematic review of the international literature to investigate the frequency, severity, and time to onset of recurrence.Details of the methodology of the review are provided in the additional material.After ruling out 3,527 articles, we eventually selected 35 for quantitative analysis (Figure A1).The 35 studies on recurrence covered 34,864 patients. The median percentage of recurrence was 27% (IQR, 12.8-61.43) (Table A1, A2). The median duration of studies was 5 years (range, 1-13 years).Retrospective and prospective cohorts accounted for only 31.43%(Table 1 and Table A2).Studies from Australia reported the highest rates (up to 57.27 recurrences per 100 person-years) (Figure 1, Table A3), with prevalence values higher than 50% for at least 1 recurrence. 3,4 For both prevalence and incidence, differences between continents were statistically significant (p < .01) and heterogeneity was high (I 2 > 99%).Studies carried out in 2 age groups (under 19 years and all ages) did not reveal differences for incidence or prevalence of recurrence rates (p = .88 and .67, respectively) (Table A3), although differences may be diluted because of the inclusion of children and adolescents in the studies covering all age groups. We found no studies that provided data on all causes of recurrence for the >18-year-old group.Given that the review revealed up to 25 different ways of grouping ages, it was impossible to aggregate them into more homogeneous categories.By principal cause of anaphylaxis, the lowest incidence rates were found for recurrences due to drugs and exercise, although only 1 study 3 addressed both causes. The lowest prevalence rates were for drugs, with the differences also being significant for both prevalence and incidence (p < .01) (Figure 1, Table A3).Other potential explanations for the heterogeneity of the metaanalysis include the incorrect classification of anaphylaxis (underand over-diagnosis) in settings other than allergy departments,
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.