Risk factors in anaphylaxis

Certain individuals are more prone to episodes of anaphylaxis than others, and evidence of risk factors should be elicited during history taking or retrieved from existing documentation (Figure 2). These risk factors include patients with atopic illness such as hay fever, eczema and, in particular, asthma, which is most typically the case in children and young adults with food-related anaphylaxis (Brown 2006). Approximately 12% of those with anaphylaxis also have a family history of allergy or anaphylaxis, making this a significant risk factor (NICE 2011, American Academy of Allergy, Asthma & Immunology 2013).

Figure 2

Latex-associated anaphylaxis, as already stated, peaked in incidence globally during the 1980s, probably as a consequence of universal precautions in response to the dangers of HIV transmission (Reading 2009), but remains a potential source of immune-driven anaphylaxis for healthcare staff and patients (Jevon 2010, Nelsons Solicitors 2012). Cases of healthcare staff and organisations being held medico-legally culpable for such events have been documented (Legal Eagle Eye Newsletter for the Nursing Profession 2012).

Certain medications also make patients more susceptible to anaphylaxis and/or inhibit their response to treatment, an example being beta-blockers used to treat hypertension and, in certain cases, anxiety. Patients taking beta-blockers for whatever reason are more likely to experience anaphylaxis and may be resistant to the effects of adrenaline treatment during an episode (Horn and Hansten 2009, Jacobsen and Gratton 2011, Mustafa 2012). This is because the drug partly neutralises the effect of adrenaline by maintaining an artificially low heart rate, thereby reducing cardiac output. This exacerbates existing hypotension secondary to the anaphylactic response (Goddet et al 2006).

Note: It is recommended that patients deemed at risk of anaphylaxis, or who have documented anaphylaxis, are not prescribed beta-blockers (Horn and Hansten 2009).

Learning points

1. The risk factors of anaphylaxis include patients with atopic illness such as hay fever, eczema and, in particular, asthma, which is most typically the case in children and young adults with food-related anaphylaxis. Latex, family history, and certain medications are also considered as significant risk factors.
2. Latex-associated anaphylaxis is a potential source of immune-driven anaphylaxis for healthcare staff and patients, probably as a consequence of universal precautions in response to the dangers of HIV transmission.
3. Patients taking beta-blockers are more likely to experience anaphylaxis and may be resistant to the effects of adrenaline treatment. This is because the drug partly neutralises the effect of adrenaline by maintaining an artificially low heart rate, thereby reducing cardiac output. Hence patients deemed at risk of anaphylaxis are not prescribed beta-blockers.