title: Prevalence of pulmonary embolism in acute exacerbations of COPD: a systematic review and metaanalysis.
abstract: BACKGROUND
  Nearly 30% of all exacerbations of COPD do not have a clear etiology. Although pulmonary embolism (PE) can exacerbate respiratory symptoms such as dyspnea and chest pain, and COPD patients are at a high risk for PE due to a variety of factors including limited mobility, inflammation, and comorbidities, the prevalence of PE during exacerbations is uncertain.
  
  
  METHODS
  A systematic review of the literature was performed to determine the reported prevalence of PE in acute exacerbations of COPD in patients who did and did not require hospitalization. The literature search was performed using MEDLINE, CINAHL, and EMBASE, and complemented by hand searches of bibliographies. Only cross-sectional or prospective studies that used CT scanning or pulmonary angiography for PE diagnosis were included.
  
  
  RESULTS
  Of the 2,407 articles identified, 5 met the inclusion criteria (sample size, 550 patients). Overall, the prevalence of PE was 19.9% (95% confidence interval [CI], 6.7 to 33.0%; p = 0.014). In hospitalized patients, the prevalence was higher at 24.7% (95% CI, 17.9 to 31.4%; p = 0.001) than those who were evaluated in the emergency department (3.3%). Presenting symptoms and signs were similar between patients who did and did not have PE.
  
  
  CONCLUSIONS
  One of four COPD patients who require hospitalization for an acute exacerbation may have PE. A diagnosis of PE should be considered in patients with exacerbation severe enough to warrant hospitalization, especially in those with an intermediate-to-high pretest probability of PE.
authors.affiliation: Department of Medicine, Respiratory Division, University of British Columbia, Heart and Lung Center, James Hogg iCAPTURE Center for Cardiovascular and Pulmonary Research at St. Paul's Hospital, Vancouver, BC, Canada.
authors.forename: Jacques
authors.initials: J
authors.lastname: Rizkallah
authors.affiliation: Department of Medicine, Respiratory Division, University of British Columbia, Heart and Lung Center, James Hogg iCAPTURE Center for Cardiovascular and Pulmonary Research at St. Paul's Hospital, Vancouver, BC, Canada.
authors.forename: S F Paul
authors.initials: SFP
authors.lastname: Man
authors.affiliation: Department of Medicine, Respiratory Division, University of British Columbia, Heart and Lung Center, James Hogg iCAPTURE Center for Cardiovascular and Pulmonary Research at St. Paul's Hospital, Vancouver, BC, Canada. Electronic address: dsin@mrl.ubc.ca.
authors.forename: Don D
authors.initials: DD
authors.lastname: Sin
mesh_terms: D000208:Acute Disease; D006801:Humans; D029424:Pulmonary Disease, Chronic Obstructive / Q000150:complications* / Q000175:diagnosis / Q000503:physiopathology; D011655:Pulmonary Embolism / Q000209:etiology*; D012307:Risk Factors; D054556:Venous Thromboembolism / Q000209:etiology