Prevalence of β2-agonist inhalation for outpatients in a pediatric emergency center during enterovirus D68 epidemic

Background Enterovirus D68 (EV-D68) has been reported to have caused severe bronchial asthma attacks and hospitalization epidemics in Japan in September 2015. Objective To investigate the prevalence of β2-agonist inhalation in a pediatric emergency center during a period of increased hospitalization for bronchial asthma, which was suggested to be associated with EV-D68. Methods We investigated the prevalence of β2-agonist inhalation in a pediatric emergency center in Saga city, Japan, from April 2013 to October 2015, and also clarified the trends in bronchial asthma hospitalization in the same area during that time. Results The prevalence of β2-agonist inhalation in the pediatric emergency center, September 2015 was highest when EV-D68 became widespread. The monthly average for β2-agonist inhalation during the study period was 91 cases, but the count in September 2015 was 255 cases. Hospitalized cases of bronchial asthma in September 2015 were increased for age ≥3 years and not increased for age <3 years, but the prevalence of β2-agonist inhalation at the pediatric emergency center was increased even under the age of 3 years. Conclusion During the epidemic period for EV-D68, cases requiring β2-agonist inhalation were increased. The EV-D68 epidemic may be related to not only severe cases requiring hospitalization, but also exacerbation of relatively mild symptoms of bronchial asthma.