title: Body mass index and asthma severity among adults presenting to the emergency department.
abstract: OBJECTIVE
  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.
  
  
  METHODS
  Multicenter, prospective cohort study.
  
  
  METHODS
  Twenty-six North American EDs.
  
  
  METHODS
  Five hundred seventy-two patients aged 18 to 54 years presenting with acute asthma.
  
  
  METHODS
  None.
  
  
  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, > or =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 beta-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 beta-agonists before ED presentation, initial PEF rate) were due, in large part, to confounding by sex.
authors.affiliation: Department of Pulmonary and Critical Care, Massachusetts General Hospital, 55 Fruit Street, Boston, MA 02114, USA.
authors.forename: Carey Conley
authors.initials: CC
authors.lastname: Thomson
authors.forename: Sunday
authors.initials: S
authors.lastname: Clark
authors.forename: Carlos A
authors.initials: CA
authors.lastname: Camargo
mesh_terms: D000208:Acute Disease; D000293:Adolescent; D000328:Adult; D001249:Asthma / Q000453:epidemiology / Q000209:etiology*; D015992:Body Mass Index; D002170:Canada; D015331:Cohort Studies; D015897:Comorbidity; D016001:Confidence Intervals; D004636:Emergency Service, Hospital / Q000706:statistics & numerical data*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009765:Obesity / Q000150:complications* / Q000453:epidemiology; D016017:Odds Ratio; D011446:Prospective Studies; D012307:Risk Factors; D014481:United States