title: The impact of body mass index on inpatient- versus outpatient-treated chronic obstructive pulmonary disease exacerbations.
abstract: BACKGROUND
  Increased body weight has been associated with worse prognoses for many chronic diseases; however, this relationship is less clear in patients with chronic obstructive pulmonary disease (COPD), with underweight patients experiencing higher morbidity than normal or overweight patients.
  
  
  OBJECTIVE
  To assess the impact of body mass index (BMI) on the risk for COPD exacerbations.
  
  
  METHODS
  The present study included 115 patients with stable COPD (53% women; mean [± SD] age 67±8 years). Height and weight were measured to calculate BMI. Patients were followed for a mean of 1.8±0.8 years to assess the prospective risk of inpatient-treated exacerbations and outpatient-treated exacerbations, all of which were verified by chart review.
  
  
  RESULTS
  Cox regression models revealed that underweight patients were at greater risk for inhospital-treated exacerbations (RR 2.93 [95% CI 1.27 to 6.76) relative to normal weight patients. However, overweight (RR 0.59 [95% CI 0.33 to 1.57) and obese (RR 0.99 [95% CI 0.53 to 1.86]) patients did not differ from normal weight patients. All analyses were adjusted for age, sex, length of diagnosis, smoking pack-years, forced expiratory volume in 1 s, and time between recruitment and last exacerbation. BMI did not influence the risk of out-of-hospital exacerbations.
  
  
  CONCLUSIONS
  The present study showed that underweight patients were at greater risk for inhospital exacerbations. However, BMI did not appear to be a risk factor for out-of-hospital exacerbations. This suggests that the BMI-exacerbation link may differ according to the nature of the exacerbation, the mechanisms for which are not yet known.
authors.affiliation: Montreal Behavioural Medicine Centré, Hôpital du Sacre-Coeur de Montréal, Quebec.
authors.forename: Ariane
authors.initials: A
authors.lastname: Jacob
authors.forename: Catherine
authors.initials: C
authors.lastname: Laurin
authors.forename: Kim L
authors.initials: KL
authors.lastname: Lavoie
authors.forename: Gregory
authors.initials: G
authors.lastname: Moullec
authors.forename: Maxine
authors.initials: M
authors.lastname: Boudreau
authors.forename: Catherine
authors.initials: C
authors.lastname: Lemière
authors.forename: Simon
authors.initials: S
authors.lastname: Bacon
mesh_terms: D000368:Aged; D015992:Body Mass Index; D018450:Disease Progression; D005260:Female; D006801:Humans; D007297:Inpatients; D008297:Male; D008875:Middle Aged; D010045:Outpatients; D050177:Overweight / Q000150:complications; D016016:Proportional Hazards Models; D011446:Prospective Studies; D029424:Pulmonary Disease, Chronic Obstructive / Q000453:epidemiology* / Q000209:etiology / Q000503:physiopathology*; D012307:Risk Factors; D013851:Thinness / Q000150:complications