Chest
Volume 124, Issue 3, September 2003, Pages 795-802
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Clinical Investigations
ASTHMA
Body Mass Index and Asthma Severity Among Adults Presenting to the Emergency Department

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Study objectives:

Among adults presenting to the emergency department (ED) with acute asthma, we sought to determine the prevalence of obesity, and the relation of body mass index (BMI) to asthma severity in this high-risk population.

Design:

Multicenter, prospective cohort study.

Setting:

Twenty-six North American EDs.

Participants:

Five hundred seventy-two patients aged 18 to 54 years presenting with acute asthma.

Interventions:

None.

Measurements and results:

A standardized interview assessed demographic characteristics, asthma history, and details of the current asthma exacerbation. Data on ED medical management and disposition were obtained by chart review. Three of four asthmatic patients were either overweight (BMI, 25 to 29.9; 30%) or obese (BMI, ≥ 30; 44%). Normal weight/underweight, overweight, and obese patients did not differ on several markers of chronic asthma severity; obese subjects tended to rate symptoms more severely and to use more inhaled β-agonists in the 6 h hours prior to ED presentation despite a significantly higher initial percentage of predicted peak expiratory flow (PEF) [44%, 45%, and 51%, respectively; p < 0.05]. The three BMI groups responded similarly to acute therapy in the ED, with all groups demonstrating reversible airway obstruction. The sex distribution by BMI group differed markedly (p < 0.001), with women less often overweight (40% vs 24%) and more often obese (30% vs 52%). Since women were more likely have a higher initial PEF (45% vs 53%, p < 0.001), we stratified by sex to further examine the relation of BMI to asthma severity. The observed BMI-asthma associations were due largely, but not entirely, to confounding by sex.

Conclusions:

Despite lingering concerns about the veracity of “asthma” among obese individuals, asthma exacerbations among obese and nonobese adults were remarkably similar. Potential differences (eg, in symptom perception, use of inhaled β-agonists before ED presentation, initial PEF rate) were due, in large part, to confounding by sex.

Section snippets

Materials and Methods

This prospective cohort study was performed during November 2000 to May 2001 as part of the Multicenter Airway Research Collaboration (MARC).28 Using a standardized protocol, investigators at 26 EDs in 15 US states and 1 Canadian province provided 24-h per day coverage for a median of 2 weeks. All patients were managed at the discretion of the treating physician. Inclusion criteria were physician diagnosis of acute asthma, age 18 to 54 years, and ability to give informed consent. Repeat visits

Results

The 572 patients had a mean age of 37 ± 10 years, and 66% (95% CI, 62 to 70) were women. As expected in this urban population, most subjects were black (44%) or Hispanic (26%), with only 30% white. The smoking status of these ED patients was never smoker (38%), former smoker (26%), and current smoker (36%). Only 3% reported comorbid COPD and the exclusion of these patients from analyses did not materially change any results (data not shown).

Figure 1shows the BMI classification of these

Discussion

Many epidemiologic studies have noted the striking increase in both obesity1,2,3,5,6,7 and asthma,13,14 and both cross-sectional16,22,24,25,26,27,34,35 and longitudinal8,36,37,38 studies have attempted to document a link between these two chronic disorders. Our study is the first to examine the association between BMI and acute asthma severity among adults presenting to the ED. The prevalence of obesity among asthmatic adults in the ED was significantly higher than that of adults from the

Conclusion

In conclusion, our study supports the assertion that obese adults present to the ED with asthma exacerbations that are remarkably similar to those of nonobese adults. Compared to normal/underweight and overweight individuals, obese individuals were treated similarly and responded similarly to treatment. At least in the ED setting, these real-world data refute claims that the asthma of many obese individuals is not true asthma but instead an exaggerated dyspnea without evidence of airway

EMNet Steering Committee

Edwin D. Boudreaux, PhD; Barry E. Brenner, MD, PhD; Carlos A. Camargo, Jr, MD (Chair); Rita K. Cydulka, MD; Theodore J. Gaeta, DO, MPH; Michael S. Radeos, MD, MPH.

EMNet Coordinating Center

Keith Brinkley, MA; Carlos A. Camargo, Jr, MD (Director); Sunday Clark, MPH; Jennifer A. Emond, MS; Jessica L. Hohrmann, MPH; Sunghye Kim, MD (all at Massachusetts General Hospital, Boston).

Principal Investigators at the 30 Participating Sites

M.P. Blanda (Akron City Hospital, Akron, OH); E.D. Boudreaux (Earl K. Long Memorial Hospital, Baton Rouge, LA); J.C. Brancato (Connecticut

ACKNOWLEDGMENT

We thank the MARC Investigators for their ongoing dedication to emergency airway research.

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    Reproduction of this article is prohibited without written permission from the American College of Chest Physicians (e-mail:[email protected]).

    Dr. Thomson is supported by grant HL-707427, and Dr. Camargo by grant HL-63841 from the National Institutes of Health (Bethesda, MD). The project was supported by grant HL-63253 from the National Institutes of Health, and by an unrestricted grant from GlaxoSmithKline (Research Triangle Park, NC).

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