Background: Emergency department (ED) visits for acute asthma provide an important marker of morbidity.
Objective: To describe the epidemiology of ED visits for acute asthma.
Methods: We obtained data from the National Hospital Ambulatory Medical Care Survey, 1993 to 2005, and used the primary diagnosis code for asthma (493) to identify cases. We calculated national estimates by using assigned patient visit weights and national rates per 1000 US population with demographic-specific population data from the US Census Bureau.
Results: From 1993 to 2005, there were approximately 23,800,000 asthma visits, representing 1.8% of all ED visits, or an overall rate of 6.7 visits per 1000 US population. The national visit rate rose between 1993 and 1998 (P(trend) = .05), but was stable (or possibly decreasing) from 1998 to 2005 (P(trend) = .07). Although rates for white subjects decreased by 25% from 1998 to 2005 (P(trend) = .02), the rates for black subjects remained constant (P(trend) = .80). The overall asthma-related ED visit rate was highest among the following groups: age <10 years (13), women (7.2), black subjects (19), Hispanic subjects (7.1), and subjects in the Northeast (9.2). ED administration of inhaled anticholinergic agents increased 20-fold and systemic corticosteroids increased 2-fold from 1993 to 2005 (P(trend) = .02 and .03, respectively), whereas inhaled beta-agonist and inhaled corticosteroid administration was stable (P(trend) = .09 and .34, respectively).
Conclusion: Although asthma-related ED visit rates showed a significant upward trend from 1993 to 1998, our results support the emerging view that the asthma epidemic may have reached a plateau. Nevertheless, the higher visit rates observed among specific demographic groups and widening disparities, particularly among black subjects, remain problematic and warrant further investigation.