The frequency and characteristics of epinephrine use during in-flight allergic events

Background: Allergic reactions account for 2% to 4% of medical events in-flight and 5.5% of all medical events in passengers 18 years and under. Objective: To evaluate the incidence of in-flight allergic events including availability, use of epinephrine, and final patient outcome. Methods: We conducted a retrospective study of the ground-based medical service (GBMS) database from January 2017 to December 2019 for all allergic events and epinephrine utilization. Results: A total of 140,579 in-flight medical events (IFMEs) were initially retrieved from the period between January, 2017 and December, 2019, of which 4230 (3.0%) unique cases were identified as allergic events. Epinephrine administration was recommended in 398 passengers by GBMS. Of those, 328 (82.4%) ultimately received at least 1 dose of epinephrine. In multivariate analysis, there was a significant difference in the involvement of volunteers (odds ratio [OR], 3.19; P value <.001; 95% confidence interval [CI], 2.43-4.16), availability of autoinjectors (OR, 2; P value <.001; 95% CI, 1.55-2.58), flight diversion (OR, 11.21; P value <.001; 95% CI, 3.60-34.89), and hospital transport (OR, 6.58; P value <.001; 95% CI, 4.62-9.38) between the 2 groups. Passengers older than 12 years of age were at a higher risk for epinephrine administration. In the secondary analysis of 51 airlines that consistently use GBMS for all IFMEs, the incidence of allergic events was found to be 0.91 cases per million passengers. The incidence of severe in-flight allergic emergencies requiring epinephrine administration was 0.08 cases per million passengers or 12.5 million passengers for 1 event. Conclusion: IFME requiring epinephrine administration is rare with an incidence rate of 1 event in 12.5 million passengers. The risk for epinephrine administration is higher in passengers more than 12 years of age and is associated with significantly higher flight diversion, hospital transport, and involvement of medical volunteers.