Anaphylaxis: patient diagnosis and treatment part 2

Demographic data

It is estimated that in the UK there is one episode of anaphylaxis for approximately every 1,333 of the population (NICE 2011). In the UK, it is reported that up to 220,000 people under the age of 44 years have experienced an anaphylactic reaction to nuts, with up to 500,000 having a similar reaction to venom, predominantly in the form of insect bites and stings (DH 2006). NICE (2011) recommends further research on prevalence in the UK. This is because some episodes may be unrecorded, or recorded as episodes of asthma or acute allergy (Caton and Flynn 2013).

Incidence of anaphylaxis

Where data are available, the incidence of anaphylaxis has been noted to be rising and the age range of those affected varies from five months to 85 years (House of Lords Science and Technology Committee 2007). The lifetime prevalence of anaphylaxis in the UK increased by 51% from 50.0/100,000 population in 2001 to 75.5/100,000 in 2005, and the prescription of adrenaline (epinephrine) injectors as treatment for anaphylaxis rose by 97% (equating to more than 21,000 prescriptions) during this period (Sheikh et al 2008).

In the US, it is estimated that between 125 and 200 deaths are attributable to anaphylaxis annually (Lockey and McCann 2012, Mustafa 2012). The majority of these deaths are attributed to food-related anaphylaxis, and an annual incidence of almost 11 cases per 100,000 of the population in the US is broadly similar to rates in Europe (Sheikh et al 2008, Mustafa 2012).

Between one third and one half of anaphylactic episodes managed in emergency care in the US, Europe and Australia are a result of ingestion of foods by children. However, Denmark reported significantly lower rates per 100,000 of the population, with around one third of the incidence of other developed countries, where rates overall have been found to be generally higher than in non-developed countries (Crusher 2004, DH 2006, Sheikh et al 2008, Lockey and McCann 2012).

Between 1% and 5% of people taking penicillin will experience an allergic-type response, with approximately 0.2% of these being anaphylactic (Lockey and McCann 2012). Data from the US, Australia, France and Switzerland estimate anaphylactic reactions to venomous stings occur in 0.4-4% of the population, with a rate of 40 deaths annually in the US (Elsevier 2012, Lockey and McCann 2012).

Idiopathic anaphylaxis

Definition

Idiopathic anaphylaxis is defined as recurrent episodes of the reaction, where no causative factor can be identified, and these may occur with varying degrees of frequency (Greenberger 2007).

Certain groups of women appear to develop catamenial anaphylaxis concurrently with their menstrual cycle. In certain severe and recurrent cases, hormone therapy may be necessary (Lieberman 2009, Mustafa 2012). There has otherwise been no discernible difference noted between male and female incidence, although males are reported to experience an increased incidence of anaphylactic reactions subsequent to venomous bites and stings than females (Elsevier 2012).

Complete time out activity 3

The relatively high rate of idiopathic anaphylaxis makes management challenging. What advice and treatment should the healthcare professional provide to patients with idiopathic anaphylaxis, and parents of children with this type of reaction, to reduce the risk of morbidity and mortality?

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Learning points

1. The incidence of anaphylaxis has been noted to be rising and the age range of those affected varies from five months to 85 years. Between 1% and 5% of people taking penicillin will experience an allergic-type response, with approximately 0.2% of these being anaphylactic.
2. Idiopathic anaphylaxis is defined as recurrent episodes of the reaction, where no causative factor can be identified, and these may occur with varying degrees of frequency. Idiopathic episodes account for 20% of anaphylactic reactions.
3. Certain groups of women appear to develop catamenial anaphylaxis concurrently with their menstrual cycle. There has otherwise been no discernible difference noted between male and female incidence, although males are reported to experience an increased incidence of anaphylactic reactions subsequent to venomous bites and stings than females.