February 17, 2021

expert reaction to study looking at UK death rate and hospital admissions due to food-induced anaphylaxis

A study published in the BMJ looks at UK death rate and hospital admissions for food-induced anaphylaxis over a 20-year period (1998-2018).

Prof Sir Stephen Holgate, Professor of Immunopharmacology at Southampton University and a trustee of the Natasha Allergy Research Foundation, said:

“The study is robust and used very standard methodology.  They recognise their shortcomings but as far as I can tell using standard case definitions they have done their best with these data.  The study though does not tell us much that’s new.

“While we welcome this valuable analysis, the three-fold increase in anaphylaxis hospital admissions caused by food allergies over the past 20 years only captures part of the problem and may be an underestimate – the lack of allergy specialists means that anaphylaxis is being underdiagnosed and underfollowed up; hence anaphylactic deaths, all of which are preventable.

“This study only looked at UK hospital admissions and we know that many people who experience a severe food allergy will be treated as an outpatient in A&E.  Therefore, the true toll of severe and life-threatening food allergies in the UK is likely to be much higher especially since anaphylaxis masquerades as other clinical conditions such as asthma, angioedema and urticaria (hives).

“It is imperative that we understand the full scale of food allergies in the UK so that those with a food allergy can get the care they need to prevent unnecessary anaphylaxis and deaths.

“The introduction of a national register of anaphylaxis fatalities would provide this essential information.”

Dr Alexandra Santos, Consultant in Paediatric Allergy, King’s College London, MRC Clinician Scientist & Principal Investigator of the Asthma UK Centre in Allergic Mechanisms of Asthma, and Chair of the Board of the Food Allergy Interest Group of the European Academy of Allergy and Clinical Immunology (EAACI), said:

“The paper by Paul Turner and colleagues reports important data about the rates of food anaphylaxis in the UK over the last 20 years (1998-2018).  It is important to have these figures in order to better appreciate the impact that food allergy has in our society and invest on ways to alleviate this.

“The main findings were that hospital admissions for anaphylaxis caused by food allergies have increased 179%, especially in children aged 0-14 years, but fortunately fatality rates decreased over the same period and deaths were less frequent in children compared to adults.  The decrease in fatalities coincided with a 336% increase in the prescription of adrenaline auto-injectors and may have contributed to the discrepancy between the frequency of allergic reactions requiring hospital admission and the frequency of deaths as a result of food anaphylaxis.

“Immediate points for reflection are:

“The increasing rate of hospital admissions probably reflects the increasing prevalence of food allergy and how common accidental reactions to allergens are.

“Although fatalities have decreased, we should not underestimate the negative impact that food allergy can have on patients and families and further research into assessing the various aspects of health and life this can affect is highly needed.

“Another aspect that requires close monitoring in the future is the possibility that the increase in prevalence in the younger age group may translate in increased number of severe food allergy (and fatalities) when these children reach adolescence and adulthood, as these were the age groups most affected by fatal outcomes.

“Overall, these worrying figures illustrate the need for specific treatment that can modify the course of the disease and for preventative interventions that can reverse the food allergy epidemic.”

Dr Michael Walker, Consultant Referee Analyst, Laboratory of the Government Chemist (LGC), said:

“This is a robust study including, for the first time, the whole UK.  It comes from a highly respected and experienced team who have carefully examined official statistics and inquest reports.  The press releases accurately reflect the science although the Imperial College Release is a better description of the paper.

“In my view the four key messages from the study are:

“Hospital admissions for serious allergic reactions (anaphylaxis) due to food have increased over the past 20 years.  In 2011, the National Institute for Health and Care Excellence (NICE) recommended paediatric hospital admission for children under 16 after emergency treatment for anaphylaxis but although 2011 saw a substantial increase in hospital admissions the rate of increase has persisted from 2014 and cannot just be the impact of the NICE guidance.

“More reassuringly, deaths from food induced anaphylaxis, already rare, have declined over the same time period.

“The study showed cows’ milk is the commonest single cause of fatal food-induced allergic reactions in school-aged children.  Children younger than five were most likely to be admitted to hospital with anaphylaxis, but the rate of deaths in this age group was low.  Dairy foods form an important part of the diet, although cow’s milk allergy is one of the most common childhood allergies its absolute prevalence in the general population is low, probably less than 1 in a hundred children under two, and most young children with allergy to cow’s milk will outgrow their allergy.  But in older children with persisting milk allergy, it is clearly a common cause of anaphylaxis and life threatening reactions.  This is of concern because although awareness of peanut and tree nut allergy is high, skimmed milk powder is widely used and increased awareness of milk allergy in the food industry could help reduce the risk to school age children, particularly those with other concomitant atopic diseases such as asthma.

“The study found food anaphylaxis deaths peaked during teenage years, these young lives lost, and the fear of anaphylaxis blights the lives of those with food allergy emphasising the need for renewed work on prevention of severe allergic reactions to food by good allergen risk assessment and effective risk management in the food chain.”

Hannah Whittaker, Specialist Paediatric Dietitian and BDA (British Dietetic Association) media spokesperson, said:

“Study limitations include:

“Those who attended A&E without a hospital admission were excluded – this may have changed the data set and demographic of results.

“The authors used the ‘probability’ that admission was due to food induced anaphylaxis, stating deaths caused by an acute asthma exacerbation were included only when strong evidence existed that the episode was triggered by an identified allergen to which the deceased patient had a known allergy – this may have led to miscoding.

“The increase in the prescription of adrenaline autoinjectors may directly correlate with a reduction in deaths due to anaphylaxis.

“The study says “In 2011, the National Institute for Health and Care Excellence published guidance that recommended children younger than 16 years should be admitted to hospital under the care of a paediatric medical team after emergency treatment for suspected anaphylaxis” – this correlated with results, showing an increase in children after 2011.  The authors stated that they allowed for this and this trend continued to 2018 however this cannot be for certain.

“One quarter of patients were unable to identify the food trigger therefore making it difficult to target groups for intervention.

“Probable cause of death not definitive, open to error.

“The study says “While we included reports of fatal food anaphylaxis for people living in Scotland and Northern Ireland, we were unable to cross check these data with the equivalent databases in these nations (ONS in England & Wales)” and “Between1998 and 2018, there were 255 913 admissions, of which 101 891 (39.8%) were coded as (all cause)anaphylaxis; the remainder also included day cases (for example, allergy testing such as food challenges)” – unsure if this led to anaphylaxis due to challenge.  Miscoding of anaphylaxis.

“Not full picture as no A&E data available – may have changed figures.

“The sex ratio for anaphylaxis admissions due to an unspecified trigger in younger children (fig 3, middle panel) implies that many of these admissions might have been due to a food trigger but were coded incorrectly.

“Coding is open to medication interpretation.

“Limitations on data received from Wales due to data protection therefore may be responsible for lower rates observed.

“Study strengths include:

“No patient reporting therefore less likely to be over/under reporting.

“Showed that death from anaphylaxis was greater in teenage years and also that this group had more hospital admissions.

“Children <5 most likely to be admitted due to anaphylaxis but death rate was lower than in any age group.

“Overall this study allows identification of trends in food allergies and how they are on the rise.  It gives scope for intervention into teenage allergy and those in mid-adulthood where there has been seen to be the greatest levels of miscontrol.  It also gives cause for further support for parents/carers of children with IgE milk allergy and also awareness for health professionals.”

‘Food anaphylaxis in the United Kingdom: analysis of national data, 1998-2018’ by Alessia Baseggio Conrado et al. was published in the BMJ at 23:30 UK time on Wednesday 17 February 2021.

DOI: 10.1136/bmj.n251

Declared interests

Dr Alexandra Santos: “No COI related to this article. In terms of my usual declaration of potential COI, it is: Dr. Santos reports grants and fellowships from Medical Research Council (MR/M008517/1; MR/T032081/1); grants from Food Allergy Research and Education, Asthma UK, Immune Tolerance Network/National Institute of Allergy and Infectious Diseases (NIAID, NIH) and the NIHR through the Biomedical Research Centre (BRC) award to Guy’s and St Thomas’ NHS Foundation Trust; consultancy or speaker fees from Thermo Scientific, Nutricia, Infomed, Novartis, Allergy Therapeutics, Buhlmann, as well as research support from Buhlmann and Thermo Scientific through a collaboration agreement with King’s College London.”

Dr Michael Walker: “The views expressed here are those personally of Michael Walker and do not represent the official views of LGC.

Interests: Paid employment or self-employment – I am a consulting chemist (Michael Walker Consulting Ltd) through which I am a chemico-legal expert witness in the Northern Ireland courts. I also have a contract to science manage technical appeals to the Government Chemist on the results of official controls in the food and feed sectors, sometimes including allergens, and advise on analytical allergen detection research in the publically funded Government Chemist Programme in LGC, https://www.gov.uk/government/organisations/government-chemist. As part of this I have worked and published with one of the authors of the paper (Hazel Gowland).

I sit on the IFST Science Committee

Grant funding – see above.

Voluntary appointments – Co-Chair ILSI-Europe Expert Group, Allergen Quantitative Risk Assessment, honorary professor IGFS, Queen’s University, Belfast

Memberships – Michael Walker Consulting Ltd is a corporate member of Anaphylaxis Campaign, Michael Walker is a member of the European Academy of Allergy & Clinical Immunology.

Decision-making positions – none directly relevant.

Other financial interest – none.”

Hannah Whittaker: “No conflicts to declare.”

None others received.