To describe the rate and characteristics of anaphylaxis cases presenting to out-of-hospital emergency medical services (EMS).
Over a 2-year period from May 2013, paramedics responding to ambulance calls in the Outaouais region of Quebec collected data on patients with anaphylaxis, as part of the Cross-Canada Anaphylaxis Registry. Demographics, reaction characteristics and treatments were recorded at the time of patient evaluation.
The incidence of anaphylaxis among the 67,220 ambulance calls received during the study period remained stable in years 1 and 2, at 0.31% [n=104; 95% CI 0.25%, 0.37%] and 0.36% [n=119; 95% CI 0.30%, 0.43%], respectively. The median age was 43.3 years [interquartile range: 20.9, 60.3], with female predominance (60.1%; 95% CI 53.3%, 66.5%). Food (37.2%; 31.0%, 44.0%), drugs (19.7%; 14.8%, 25.7%) and venom (17.9%; 13.3%, 23.7%) were the top triggers. Severe reactions (defined by the presence of cyanosis, SpO2<92%, respiratory arrest, hypotension, dysrhythmia, confusion or loss of consciousness) were more likely in males [OR 2.1; 1.1, 4.4] and during exercise [OR 5.2; 1.2, 22.4). Epinephrine was not administered for moderate-severe anaphylaxis in 25.0% of cases (95% CI 19.1, 32.0). The presence of serious reaction was the only factor associated with epinephrine administration [OR=1.26; 1.1, 1.5].
Conclusions: Our results draw from the first prospectively documented data of anaphylaxis cases presenting to out-of-hospital EMS. The results reflect previously identified risk factors for anaphylaxis, with food, drugs and insect stings as the most common culprits. The suboptimal proportion of cases treated with epinephrine highlights an ongoing need for patient and health-care provider education.