Fatal anaphylaxis in Italy: Analysis of cause-of-death national data, 2004-2016.

Background: Epidemiological data on fatal anaphylaxis are underestimated worldwide. Few Italian data do exist. The aims of the study are to determine the anaphylaxis mortality rate in Italy and its associations with demographic characteristics (gender, age, and geographical distribution), and to investigate which are the most common triggers of fatal anaphylaxis.

Material And Methods: This is a descriptive study analyzing data reported to the National Register of Causes of Death database and managed by the Italian National Institute of Statistics for the years 2004-2016. An analytical method was developed to identify all the ICD-10 codes related to anaphylaxis deaths, which were divided into two classes: "Definite anaphylaxis deaths" and "Possible anaphylaxis deaths."

Results: From 2004 through 2016, 392 definite anaphylaxis deaths and 220 possible anaphylaxis deaths were recorded. The average mortality rate for definite anaphylaxis, from 2004 to 2016, was 0.51 per million population per year. Definite fatal anaphylaxis was mostly due to the use of medications (73.7%), followed by unspecified causes (20.7%) and hymenoptera stings (5.6%). Concerning possible anaphylaxis deaths, the most common cause was venom-stinging insect (51.4%). We did not find any data on food fatal anaphylaxis. Unspecified anaphylaxis accounted for 21%-28% of all cases, underlining the difficulty in accurately ascertaining the causes of fatal anaphylaxis and therefore in assigning the proper ICD-10 code.

Conclusion: This is the first study of anaphylaxis-related mortality coming from an official database of the whole Italian population. However, the actual number of deaths by anaphylaxis, and their related triggers, is probably underreported, mostly due to limitations of the current recording system, and to a poor allergy education. Corrective actions should be undertaken for the benefit of the Health System.