Anaphylaxis is increasingly common. The patient population death rate for anaphylaxis is Australia in 2013 was over double that reported in the UK
Dr Ray Mullins, an allergist in Canberra, and colleagues from Sydney and Singapore have recently reported an increase in in the number of anaphylaxis fatalities in Australia. This is currently trending towards a 3 fold increase in anaphylaxis deaths over the study period of 15 years. Mullins and colleagues had previously identified a rise in the rate of all food allergy, with the most dramatic effect in young childhood food where hospital admission analyses showed a 500% increase in children 0-4 years of age over a 10 year period. This has been shown to further increase in the subsequent 5 years.
The mortality data, extracted from analysis of coronial cases, was presented at the American Academy of Allergy, Asthma and Immunology in Los Angeles in March and the full article has appeared in Clinical and Experimental Allergy last week ahead of journal publication.
Idiopathic /unspecified anaphylaxis represent the largest proportion of fatal cases after 19 years of age. Food allergy is the most common fatal cause of anaphylaxis in childhood and despite Australia leading the world in many aspects with respects to guidelines, patient and doctor resources/training, and food allergy research/advocacy, food allergy deaths appear to have a greater trend (approximately 4-fold) over the 15 year period of analysis. Seafood, NOT nuts was the most common trigger for food anaphylaxis deaths in Australia and a co-morbidity of asthma was a significant risk for fatal reactions. When a food was involved, 90% were known to be allergic to their triggering food, whereas only 30% had experienced an anaphylaxis. This destroys the attitude that patients need to “Earn an EpiPen™”. Even when anaphylaxis had occurred due to food, adrenaline was only prescribed in 1 of 4 cases. When food anaphylaxis occurred patients were treated for asthma first and adrenaline administered in 10% of cases.
In the UK, a 615% increase in anaphylaxis episodes were documented in a recent 20 year period but there was no increase in fatalities, attributing this discordance to being possibly due to due to increasing awareness of the diagnosis, shifting patterns of behaviour in patients and health care providers, or both. The patient population death rate for anaphylaxis is Australia in 2013 was over double that reported in the UK.
Late use of adrenaline or absent use of adrenaline is risk factor for death. A history of severe food anaphylaxis is a risk factor for severe further events. But about half of the UK series of fatal food reactions occurred in patients with a history of previously mild allergic responses.
Risk factors for severe reactions include asthma, having a severe allergic burden (asthma, rhinitis, eczema), mastocytosis, alcohol, medication, concealment of allergen in food, medications including aspirin / NSAIDs, exercise, are, metabolic factors and inter-current illness. These risk factors have been summarized in recent reviews.
Expert guidelines, Emergency Medicine Specialist, Anaesthetists and Allergist/Immunologists stress the need for follow up of severe allergic events with an allergy specialist and to provide patients who have had experienced an anaphylaxis and those at significant risk of anaphylaxis with an emergency management plan and medications including an Epinephrine (Adrenaline) auto-injector device.
An Australian meta-analysis of 16 papers of ED department practices of follow up care of anaphylaxis, published in late 2015 showed: Prescription rates for self-injected adrenaline at the time of discharge following anaphylaxis varied from 0% to 68%, with a mean of 44%. Allergist referral rates ranged from 0% to 84%, with a mean of 33%.
Where to from here?
- ED awareness, direction and prescription
- Public awareness
- Government lead capacity development for review, assessment and training of those patients with a history of anaphylaxis
- Private referral, however there are long waits to see specialist allergists in Australia.
- Anaesthetists in Australia and New Zealand have published guidelines for recording, managing and following up anaesthetic drug allergy reactions.
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