Study Protocol: Preventable deaths involving anaphylaxis in England and Wales
Creators: name: Heneghan, Carl
name: Aronson, Jeffrey K
name: Brittain, Richard
name: Richards, Georgia C.
name: Dernie, Francesco
name: Bettsworth, Finley
name: Sheikh, Aziz
Publisher: name: OSF Registries
Year: 2024
Subjects: subject: Medicine and Health Sciences
subject: PFDs
subject: allergy
subject: anaphylaxis
subject: coroner reports
subject: coroners
subject: deaths
subject: inquests
subject: mortality
subject: preventable deaths tracker

description: Allergic reactions are immune-mediated inflammatory responses to allergens in the environment that are otherwise innocuous (1). It is estimated that 16% of children have an 18-year prevalence of one or more allergies (2). Such reactions can have wide-ranging outcomes, from mild urticaria or allergic rhinitis to severe systemic responses, such as angioedema and anaphylaxis (3). 

Deaths involving allergies are typically caused by anaphylaxis, a serious systemic hypersensitivity reaction with rapid onset (4). It is estimated that one in 1333 of the English population has experienced an episode of anaphylaxis (5). Although fatal anaphylaxis is rare, there are 20 to 40 deaths per year in the UK (6), and hospital admissions for all-cause anaphylaxis have doubled between 2002 and 2023 (7). 

Anaphylaxis is characterised by potentially life-threatening respiratory and/or cardiovascular compromise, and it may occur without concurrent typical skin features or circulatory shock (8). Such reactions may include the development of life-threatening pharyngeal/laryngeal oedema, bronchospasm with tachypnoea, or circulatory problems (hypotension/tachycardia). This may be due to an allergic, immunologically mediated response, a non-immunologically mediated response, or an idiopathic cause. Common precipitants of immunoglobulin E (IgE)-mediated (allergic) anaphylaxis may be foods, insect venom, some drugs, and latex (4), although many drugs can also cause anaphylaxis through non-allergic mechanisms (9). Prescribed drugs may cause anaphylactic reactions, particularly antibiotics and anaesthetic agents, and thus many anaphylactic reactions are iatrogenic, constituting about half of all deaths from anaphylaxis (6). There have also been cases where an autopsy report has mischaracterised an anaphylactic reaction as a severe asthma attack (10). 

Fatality data on anaphylaxis is limited. The UK Fatal Anaphylaxis Registry (UK FAR) collates information on cases of fatal anaphylaxis, but this is an incomplete record, as the reporting of deaths is not mandatory (11,12). Nonetheless, the UK FAR has been used to analyse anaphylaxis-related hospital fatalities, food allergy fatalities and details around these, including demographic details and the specific agent causing fatal anaphylaxis (13–15). Hospital admissions have similarly been used and found that food-induced anaphylaxis has increased from 1.23 per 100 000 population in 1998 to 4.04 per 100 000 population in 2018 in the UK but with a decrease in case fatality rate from 0.7% to 0.19% for confirmed fatal food anaphylaxis from 1998 to 2018 (16).

Coroners in England and Wales must write Prevention of Future Deaths reports (17) (hereafter known as PFDs) and send these reports to recipients who must respond within 56 days to report on the action taken to prevent similar fatalities (18,19). Previous research has analysed PFDs to identify concerns raised by coroners from a range of public health and patient problems, including deaths involving medicines and preventable deaths during the COVID-19 pandemic (20–22). However, deaths involving allergies and anaphylaxis have not yet been explored. Therefore, this study aims to explore the number of coroner reports in England and Wales that involved anaphylaxis, from inception (July 2013) to December 2023, to understand the concerns raised by coroners regarding fatal anaphylaxis.

We aim to systematically analyse the concerns raised by coroners in PFDs that mention anaphylaxis, and the responses to them, to understand what actions have been taken and lessons learnt to prevent future fatal anaphylaxis.