The relationship of fall school opening and emergency department asthma visits in a large metropolitan area

Background: Asthma morbidity is seasonal, with the fewest exacerbations occurring in summer and the most exacerbations in early fall. Objective: To determine if the fall increase in pediatric asthma emergency department (ED) visits is related to the school year start. Design: Time-series study of daily asthma ED visits taken from an administrative claims database for the years 1991 to 2002. Setting: Eleven municipal hospitals in New York City, NY. Patients: Emergency department visits with asthma as the primary diagnosis among children aged 2 to 4, 5 to 11, and 12 to 17 years and adults with asthma aged 22 to 45 years as comparative group. Main Outcome Measure: Rate of asthma ED visits after the September school opening compared with before the opening, during a 60-day window of each year.The delayed effect of school opening was examined by the lagged school-opening indicator for lag 0 through 9 days. The model adjusted for factors that may influence morbidity. There were 86 731 ED visits within the study period. Conclusion: The start of the September school year was associated with increases in pediatric asthma ED visits, particularly among grade school children.