Epinephrine dispensing patterns for an out-of-hospital population: A novel approach to studying the epidemiology of anaphylaxis

Background: The underlying rate of occurrence of anaphylaxis from all potential triggers in the general population is unknown. Objective: We sought to obtain a perspective on the epidemiology of anaphylaxis in a defined general population by studying epinephrine dispensing patterns in an out-of-hospital setting. Methods: Using an administrative claims pharmaceutical database, we analyzed dispensing data for all epinephrine formulations prescribed for out-of-hospital treatment over 5 consecutive fiscal years in a population of 1.15 million persons in the province of Manitoba, Canada. We identified the number and percentage of individuals in the general population for whom epinephrine was dispensed on one or more occasions, their age and sex, and the type of formulation dispensed. In addition to performing these analyses for the entire population of children, adults, and elderly individuals, we also performed analyses by 5-year age groupings; furthermore, for individuals younger than 5 years of age, we performed a detailed analysis by 6-month age groupings. Results: During the 5-year period, 0.95% of this defined general population had injectable epinephrine dispensed for out-of-hospital treatment. There were substantial variations in epinephrine dispensing rates across subsets of the population, ranging from 1.44% for individuals younger than 17 years of age, to 0.9% for individuals 17 to 64 years of age (inclusive), to 0.32% for those age 65 years or older. In infancy, childhood, and early adolescence boys were more likely to have epinephrine dispensed than girls. Beginning at age 15 years and continuing into adulthood, girls and women were more likely to have epinephrine dispensed than boys and men. In the elderly there were no differences in dispensing patterns between the sexes. The highest epinephrine dispensing rate (5.3%) was found for boys age 12 to 17 months. Conclusions: Epinephrine dispensing data provide a novel and practical approach for studying and monitoring the epidemiology of anaphylaxis in a community. Using this approach, we provide evidence that anaphylaxis from all triggers peaks in early childhood and then gradually declines into old age.