title: Pulmonary arterial enlargement and acute exacerbations of COPD.
abstract: BACKGROUND
  Exacerbations of chronic obstructive pulmonary disease (COPD) are associated with accelerated loss of lung function and death. Identification of patients at risk for these events, particularly those requiring hospitalization, is of major importance. Severe pulmonary hypertension is an important complication of advanced COPD and predicts acute exacerbations, though pulmonary vascular abnormalities also occur early in the course of the disease. We hypothesized that a computed tomographic (CT) metric of pulmonary vascular disease (pulmonary artery enlargement, as determined by a ratio of the diameter of the pulmonary artery to the diameter of the aorta [PA:A ratio] of >1) would be associated with severe COPD exacerbations.
  
  
  METHODS
  We conducted a multicenter, observational trial that enrolled current and former smokers with COPD. We determined the association between a PA:A ratio of more than 1 and a history at enrollment of severe exacerbations requiring hospitalization and then examined the usefulness of the ratio as a predictor of these events in a longitudinal follow-up of this cohort, as well as in an external validation cohort. We used logistic-regression and zero-inflated negative binomial regression analyses and adjusted for known risk factors for exacerbation.
  
  
  RESULTS
  Multivariate logistic-regression analysis showed a significant association between a PA:A ratio of more than 1 and a history of severe exacerbations at the time of enrollment in the trial (odds ratio, 4.78; 95% confidence interval [CI], 3.43 to 6.65; P<0.001). A PA:A ratio of more than 1 was also independently associated with an increased risk of future severe exacerbations in both the trial cohort (odds ratio, 3.44; 95% CI, 2.78 to 4.25; P<0.001) and the external validation cohort (odds ratio, 2.80; 95% CI, 2.11 to 3.71; P<0.001). In both cohorts, among all the variables analyzed, a PA:A ratio of more than 1 had the strongest association with severe exacerbations.
  
  
  CONCLUSIONS
  Pulmonary artery enlargement (a PA:A ratio of >1), as detected by CT, was associated with severe exacerbations of COPD. (Funded by the National Heart, Lung, and Blood Institute; ClinicalTrials.gov numbers, NCT00608764 and NCT00292552.).
authors.affiliation: Lung Health Center, Division of Pulmonary Allergy and Critical Care, University of Alabama at Birmingham, 422 THT 1900 University Blvd., Birmingham, AL 35294, USA. jmwells@uab.edu
authors.forename: J Michael
authors.initials: JM
authors.lastname: Wells
authors.forename: George R
authors.initials: GR
authors.lastname: Washko
authors.forename: MeiLan K
authors.initials: MK
authors.lastname: Han
authors.forename: Naseer
authors.initials: N
authors.lastname: Abbas
authors.forename: Hrudaya
authors.initials: H
authors.lastname: Nath
authors.forename: A James
authors.initials: AJ
authors.lastname: Mamary
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Regan
authors.forename: William C
authors.initials: WC
authors.lastname: Bailey
authors.forename: Fernando J
authors.initials: FJ
authors.lastname: Martinez
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Westfall
authors.forename: Terri H
authors.initials: TH
authors.lastname: Beaty
authors.forename: Douglas
authors.initials: D
authors.lastname: Curran-Everett
authors.forename: Jeffrey L
authors.initials: JL
authors.lastname: Curtis
authors.forename: John E
authors.initials: JE
authors.lastname: Hokanson
authors.forename: David A
authors.initials: DA
authors.lastname: Lynch
authors.forename: Barry J
authors.initials: BJ
authors.lastname: Make
authors.forename: James D
authors.initials: JD
authors.lastname: Crapo
authors.forename: Edwin K
authors.initials: EK
authors.lastname: Silverman
authors.forename: Russell P
authors.initials: RP
authors.lastname: Bowler
authors.forename: Mark T
authors.initials: MT
authors.lastname: Dransfield
mesh_terms: D000208:Acute Disease; D000368:Aged; D001011:Aorta / Q000033:anatomy & histology*; D001027:Aortography; D005260:Female; D006801:Humans; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D019370:Observation; D011651:Pulmonary Artery / Q000000981:diagnostic imaging / Q000473:pathology*; D029424:Pulmonary Disease, Chronic Obstructive / Q000000981:diagnostic imaging / Q000473:pathology*; D012008:Recurrence; D012307:Risk Factors; D012907:Smoking / Q000009:adverse effects; D014057:Tomography, X-Ray Computed