Study Identifies Factors that Contribute to Cases of Fatal Anaphylaxis

New research into fatal cases of anaphylaxis concludes that teens and asthmatics with known allergies face particularly high risks and should make doubly sure to carry epinephrine auto-injectors.

The study authors, who just published their findings in Allergy, Asthma & Clinical Immunology, searched the Ontario (Canada) Coroner’s database from the years 1986 to 2011 and uncovered 92 fatal cases of anaphylaxis. They then mined the records further to obtain both the suspected trigger for each case and relevant patient demographics such as age, gender and co-morbidities.

Food allergies were the most common trigger, the cause of 40 total deaths. After that came insect venom (30 cases) and drugs or other medical treatment (16 cases). The trigger for 6 of the cases was unknown.

Slightly more than half of the patients (47) had experienced previous allergic reactions to whatever triggered their fatal anaphylaxis. More than a quarter (26) had documented asthma. Only 12 of the patients were children (mean age was 46.5 years) but 10 of the children were teenagers.

The percentage of patients with known cases of asthma was far higher in this study of fatal anaphylaxis than in most studies of all anaphylaxis or in the general public, and the true number of asthmatics in the study sample may have been far greater than 26. Only 2 of the patients were known not to have asthma. No information was available about which of the remaining 64 patients did and did not have asthma.

“Additionally,” the study authors wrote, “we did not examine asthma-related deaths, so it is possible that some of these cases may have been misfiled under asthmatic deaths, which likely underestimated the number of asthmatics who died of anaphylaxis.”

All these factors, taken together, may indicate that asthma exacerbates the consequences of anaphylaxis even more than prior research has suggested and may justify allergy systematic allergy testing for all asthmatics.

It certainly demonstrates, the authors wrote, why doctors should follow guidelines for prescribing auto-injectors to asthmatics with potentially dangerous allergies and why such patients should carry them at all times.

The authors also concluded that teens faced a particularly high risk that anaphylaxis would prove fatal and that they (and their parents) should do more to uncover dangerous allergies and (again) carry auto-injectors.

Indeed, that advice holds true for all patients with known allergies. Of the 47 such patients in the study, fewer than half had been prescribed an auto-injector and fewer than half of them (10) were carrying it with them when the attack began.

“We also found that reactions occur more frequently outside of the home, particularly in public places that serve food,” the study authors wrote. “This trend highlights an educational gap in the food industry. The provision of epinephrine auto-injectors in public places such as food courts may be one way to address this, similar to how cardiac defibrillators have been implemented in public places to avoid cardiac deaths.”

For all the problems their study noted, the authors also identified one area important area where improvements are already taking place: the rate of food-related deaths fell consistently over time, despite sharp increases in the number of people with severe food allergies.

Possible explanations included everything from increased awareness to better food labeling to laws that mandate auto-injectors in schools.