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

Abstract

Objective: To describe time trends for hospital admissions due to food anaphylaxis in the United Kingdom over the past 20 years.

Design: Analysis of national data, 1998-2018.

Setting: Data relating to hospital admissions for anaphylaxis and deaths, and prescription data for adrenaline autoinjector devices.

Participants: UK population as a whole and devolved nations (England, Scotland, Wales, and Northern Ireland).

Main outcome measures: Time trends, age, and sex distributions for hospital admissions for anaphylaxis due to food and non-food triggers, and how these admission rates compare with the case fatality rate (number of fatalities as a proportion of hospital admissions).

Results: Between 1998 and 2018, 101 891 people were admitted to hospital for anaphylaxis. Of these admissions, 30 700 (30.1%) were coded as due to a food trigger. Food anaphylaxis admissions increased from 1.23 to 4.04 per 100 000 population per year (from 1998 to 2018), an annual increase of 5.7% (95% confidence interval 5.5% to 5.9%, P<0.001). The largest increase in hospital admissions was observed in children younger than 15 years, with an increase from 2.1 to 9.2 admissions per 100 000 population per year (an annual increase of 6.6%, 95% confidence interval 6.3% to 7.0%). For comparison, the annual increase was 5.9% (5.6% to 6.2%) in people aged 15-59 years and 2.1% (1.8% to 3.1%) in those aged 60 years and older. 152 deaths were identified where the fatal event was probably caused by food induced anaphylaxis. The case fatality rate decreased from 0.7% to 0.19% for confirmed fatal food anaphylaxis (rate ratio 0.931, 95% confidence interval 0.904 to 0.959, P<0.001) and to 0.30% for suspected fatal food anaphylaxis (0.970, 0.945 to 0.996, P=0.024). At least 46% (86 of 187, which also includes 35 deaths in 1992-98) of deaths were triggered by peanut or tree nut. Cow's milk was responsible for 17 of 66 (26%) deaths in school aged children. Over the same time period, prescriptions for adrenaline autoinjectors increased by 336% (estimated rate ratio 1.113, 95% confidence interval 1.112 to 1.113; an increase of 11% per year).

Conclusions: Hospital admissions for food induced anaphylaxis have increased from 1998 to 2018, however the case fatality rate has decreased. In school aged children, cow's milk is now the most common single cause of fatal anaphylaxis.