title: Clinical characteristics associated with adverse events in patients with exacerbation of chronic obstructive pulmonary disease: a prospective cohort study.
abstract: BACKGROUND
  To assist physicians with difficult decisions about hospital admission for patients with acute exacerbation of chronic obstructive pulmonary disease (COPD) presenting in the emergency department, we sought to identify clinical characteristics associated with serious adverse events.
  
  
  METHODS
  We conducted this prospective cohort study in 6 large Canadian academic emergency departments. Patients were assessed for standardized clinical variables and then followed for serious adverse events, defined as death, intubation, admission to a monitored unit or new visit to the emergency department requiring admission.
  
  
  RESULTS
  We enrolled 945 patients, of whom 354 (37.5%) were admitted to hospital. Of 74 (7.8%) patients with a subsequent serious adverse event, 36 (49%) had not been admitted after the initial emergency visit. Multivariable modelling identified 5 variables that were independently associated with adverse events: prior intubation, initial heart rate ≥ 110/minute, being too ill to do a walk test, hemoglobin < 100 g/L and urea ≥ 12 mmol/L. A preliminary risk scale incorporating these and 5 other clinical variables produced risk categories ranging from 2.2% for a score of 0 to 91.4% for a score of 10. Using a risk score of 2 or higher as a threshold for admission would capture all patients with a predicted risk of adverse events of 7.2% or higher, while only slightly increasing admission rates, from 37.5% to 43.2%.
  
  
  CONCLUSIONS
  In Canada, many patients with COPD suffer a serious adverse event or death after being discharged home from the emergency department. We identified high-risk characteristics and developed a preliminary risk scale that, once validated, could be used to stratify the likelihood of poor outcomes and to enable rational and safe admission decisions.
authors.forename: Ian G
authors.initials: IG
authors.lastname: Stiell
authors.forename: Catherine M
authors.initials: CM
authors.lastname: Clement
authors.forename: Shawn D
authors.initials: SD
authors.lastname: Aaron
authors.forename: Brian H
authors.initials: BH
authors.lastname: Rowe
authors.forename: Jeffrey J
authors.initials: JJ
authors.lastname: Perry
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Brison
authors.forename: Lisa A
authors.initials: LA
authors.lastname: Calder
authors.forename: Eddy
authors.initials: E
authors.lastname: Lang
authors.forename: Bjug
authors.initials: B
authors.lastname: Borgundvaag
authors.forename: Alan J
authors.initials: AJ
authors.lastname: Forster
authors.forename: George A
authors.initials: GA
authors.lastname: Wells
mesh_terms: D017677:Age Distribution; D000368:Aged; D000369:Aged, 80 and over; D000704:Analysis of Variance; D002170:Canada; D002423:Cause of Death; D015331:Cohort Studies; D003657:Decision Making; D018450:Disease Progression; D004636:Emergency Service, Hospital / Q000706:statistics & numerical data*; D004638:Emergency Treatment / Q000009:adverse effects / Q000379:methods; D005260:Female; D005500:Follow-Up Studies; D017052:Hospital Mortality; D006760:Hospitalization / Q000706:statistics & numerical data*; D006784:Hospitals, Teaching; D006801:Humans; D007442:Intubation, Intratracheal / Q000706:statistics & numerical data; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D010351:Patient Discharge / Q000706:statistics & numerical data; D010359:Patient Readmission / Q000706:statistics & numerical data; D011446:Prospective Studies; D029424:Pulmonary Disease, Chronic Obstructive / Q000401:mortality* / Q000503:physiopathology / Q000628:therapy*; D018570:Risk Assessment; D017678:Sex Distribution; D016019:Survival Analysis