Adult asthma exacerbations and environmental triggers: a retrospective review of ED visits using an electronic medical record.

BACKGROUND: Despite familiarity with triggers for asthma, there is little recent study on the association of triggers with the emergency department (ED) presentation of adult asthma exacerbation.
METHODS: Retrospective electronic chart review of adult patients treated in an urban teaching hospital ED with chief complaint and diagnostic coding related to asthma and upper respiratory tract infection (URI) was conducted. Monthly aeroallergen data and environmental conditions were obtained from a local allergen extract laboratory and local government sources. Data analysis was performed using Newey-West time series regression modeling with adjustment for autocorrelation or ordinary least squares linear regression modeling using outcome variables of asthma visits and admissions.
RESULTS: There were 56, 747 visits, with 554 asthma visits and 1,514 URI visits. Asthma visits (R(2) = 0.631) were positively correlated with tree pollen counts (correlation coefficient = 0.458 [0.152-0.765]) and average humidity (correlation coefficient = 1.528 [0.296-2.760]). Asthma admissions (R(2) = 0.480) were negatively correlated with average temperature (correlation coefficient = -0.557 [-1.052 to -0.061]) when adjusting for confounding by fine particulate matter.
CONCLUSIONS: The ED acute asthma exacerbation presentation is positively correlated with tree pollen and humidity, whereas need for admission is associated with dropping temperatures. These results reinforce the need for vigilance during periods of increased risk and perhaps focused preventative strategies.