Asthma morbidity is seasonal, with the fewest exacerbations occurring in summer and the most exacerbations in early fall.
To determine if the fall increase in pediatric asthma emergency department (ED) visits is related to the school year start.
Time-series study of daily asthma ED visits taken from an administrative claims database for the years 1991 to 2002.
Eleven municipal hospitals in New York City, NY.
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.
Asthma ED visits for children aged 5 to 11 years were significantly associated with school opening day, with the highest lagged rate ratio being 1.46 (95% confidence interval [CI], 1.29-1.65). For children aged 2 to 4 years, the highest rate ratio was 1.19 (95% CI, 1.06-1.35), and for children aged 12 to 17 years, the highest lagged rate ratio was 1.13 (95% CI, 0.98-1.31). The rise in adult ED visits following school opening was less substantial, with the highest lagged rate ratio being 1.07 (95% CI, 1.00-1.14).
The start of the September school year was associated with increases in pediatric asthma ED visits, particularly among grade school children.