Food anaphylaxis in the United Kingdom: analysis of national data, 1998-2018

Dear Editor

Fatal anaphylaxis: making sure all cases are counted

We read with interest the article(1) noting that whilst hospital admissions for food induced anaphylaxis have increased from 1998 to 2018, the case fatality rate has decreased over a 20-year period from 0.7% to 0.19% for confirmed food anaphylaxis.

This improved survival may indeed be the result of real improvement in management of anaphylaxis but the possibility of mis-classification of deaths should also be considered, especially given that the number of fatalities is low. Having evaluated multiple fatalities from anaphylaxis through the United Kingdom Fatal Anaphylaxis Registry (UKFAR), we wish to raise the following points of consideration.

Deaths from fatal anaphylaxis may be falsely labelled as asthma related deaths (2,3) or as sudden and unexpected deaths and thus these require systematic scrutiny. Such mislabeling can occur when the trigger causing the fatal anaphylactic reaction is different to the known food allergens of that individual. Patients with food allergies often have highly restricted diets, as a strategy to manage risk and this could increase the possibility that they have other undiagnosed food allergies. Cause of fatal anaphylaxis may be not be accurately ascertained where the allergen involved is not on the mandated list of declared food allergens or has not been previously diagnosed. (4,5). Standard post-mortem procedures with variations in individual coroner’s practices may allow slippage of accurate analysis and allergy focused examination post-death.

Fatal reactions are usually multi-factorial and for maximal learning to come from each event, it is key that data collection is optimised. One key improvement would come from more timely involvement of specialists, experienced in such allergy focused evaluations and relevant sample collection for expert analysis. For example, late collection of gastric aspirate samples, several days after the anaphylaxis event, is unlikely to confirm the relevant allergen.

At recent inquests into the deaths of teenagers from fatal food anaphylaxis, the coroner has highlighted the importance of a Fatal Anaphylaxis Registry. This was set up in 1994 by Dr Richard Pumphrey based at Manchester University NHS Foundation Trust (MFT). This registry is evolving into a national collaboration between the British Society for Allergy & Clinical Immunology (BSACI) and MFT. It is now working to draw together a multidisciplinary team including Sudden Unexpected Death in Childhood investigation panels, Her Majesty’s Coroners and experts involved in the UK register of anaphylactic reactions to ensure thorough and timely investigations of all fatal anaphylactic reactions and reflect trends in the UK more accurately . This will build on the important learnings that have emerged from previous findings of this registry (4, 5, 6). Interrogation of possible variations in immune responses in those with refractory anaphylactic reactions, unresponsive to standard guideline-led interventions, may elucidate important factors in fatal anaphylaxis and importantly, help reduce the risk of future deaths.

Yours sincerely

Vibha Sharma (1)
Tomaz Garcez (2)
Adam T Fox (3)

1 Consultant in Paediatric Allergy at Royal Manchester Children’s Hospital, Manchester Foundation Trust, Honorary Senior Lecturer University of Manchester
2 Consultant Immunologist, Manchester University NHS Foundation Trust
3 Professor of Paediatric Allergy – Guy’s & St Thomas’ Hospitals NHS Foundation Trust, London

References:
1. Conrado A, Ierodiakonou D, Gowland HM, Boyle RJ, Turner PJ, Food anaphylaxis in the United Kingdom: analysis of national data, 1998-2018: BMJ 2021;372:n251
2. Royal College of Physicians Why asthma still kills: the National Review of Asthma Deaths (NRAD) Confidential Enquiry report Royal College of Physicians: London; 2014 , Available from http://www.rcplondon.ac.uk/sites/default/files/why-asthma-still-kills-fu... .(Google Scholar)
3. González-Pérez A, Aponte Z, Vidaurre CF, Rodríguez LA. Anaphylaxis epidemiology in patients with and patients without asthma: a United Kingdom database review. J Allergy Clin Immunol 2010;125:1098-104.
4. Pumphrey RHS: Anaphylaxis: Can we tell who is at risk of a fatal reaction? Current Opinion in Allergy and Clinical Immunology 2004; 4(4):285-90.
5. Pumphrey RHS: Lessons for management of anaphylaxis from a study of fatal reactions. Clinical and Experimental Allergy, 30, 1144-50
6. Turner PJ, Gowland MH, Sharma V, et al. Increase in anaphylaxis-related hospitalizations but no increase in fatalities: An analysis of United Kingdom national anaphylaxis data, 1992-2012. J Allergy Clin Immunol 2015;135:956-63.