Asthma and lower airway disease
Improved overall trends but persistent racial disparities in emergency department visits for acute asthma, 1993-2005

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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 (Ptrend = .05), but was stable (or possibly decreasing) from 1998 to 2005 (Ptrend = .07). Although rates for white subjects decreased by 25% from 1998 to 2005 (Ptrend = .02), the rates for black subjects remained constant (Ptrend = .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 (Ptrend = .02 and .03, respectively), whereas inhaled β-agonist and inhaled corticosteroid administration was stable (Ptrend = .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.

Section snippets

Methods

We combined data from the ED component of the 1993 to 2005 National Hospital and Ambulatory Medical Care Survey (NHAMCS) to generate national estimates of ED visits for acute asthma. Our institutional review boards waived review of this analysis.

Methodological details are described elsewhere.9, 10 Briefly, the NHAMCS is a 4-stage probability sample of visits to US noninstitutional general and short-stay hospitals. The NHAMCS is conducted annually by the National Center for Health Statistics and

Results

Between 1993 and 2005, there were an estimated 23.8 million asthma-related ED visits in the United States, or an average 1.8 million visits per year. These visits represent 1.8% of all ED visits over this period. The annual rates of asthma-related ED visits per 1000 US population show an upward trend from 6.6 (95% CI, 5.4-7.7) in 1993 to 7.4 (95% CI, 6.1-9.0) in 1998 (Ptrend = .05). Rates have subsequently stabilized and may be declining, most recently to 6.0 (95% CI, 4.9-7.1) in 2005 (Fig 1).

Discussion

Most ED visits for acute asthma represent a treatment or maintenance failure8, 15 and are believed to be preventable through longitudinal disease management undertaken by both medical providers and the patient.16, 17 Rising trends in asthma morbidity in the 1980s and 1990s2 led to publication and widespread distribution of NAEPP guidelines in 1991, 1997, 2002, and most recently in 2007.6 ED visits for acute asthma are particularly disturbing because effective therapy is available, and ED

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    C.A.C. is supported, in part, by grant HL-84401 (Bethesda, Md).

    Disclosure of potential conflict of interest: A. A. Ginde receives grant support from the Emergency Medicine Foundation, Novo-Nordisk, and Bayer. J. A. Espinola declares that she has no conflict of interest. C. A. Camargo Jr has consultant arrangements with AstraZeneca and Critical Therapeutics; is on the advisory boards for Dey, Genentech, GlaxoSmithKline, and Merck; is on the speakers' bureau for AstraZeneca, GlaxoSmithKline, and Merck; and receives grant support from AstraZeneca, GlaxoSmithKline, Merck, Novartis, and Respironics.

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