title: Findings on Thoracic Computed Tomography Scans and Respiratory Outcomes in Persons with and without Chronic Obstructive Pulmonary Disease: A Population-Based Cohort Study.
abstract: BACKGROUND
  Thoracic computed tomography (CT) scans are widely performed in clinical practice, often leading to detection of airway or parenchymal abnormalities in asymptomatic or minimally symptomatic individuals. However, clinical relevance of CT abnormalities is uncertain in the general population.
  
  
  METHODS
  We evaluated data from 1361 participants aged ≥40 years from a Canadian prospective cohort comprising 408 healthy never-smokers, 502 healthy ever-smokers, and 451 individuals with spirometric evidence of chronic obstructive pulmonary disease (COPD) who had thoracic CT scans. CT images of subjects were visually scored for respiratory bronchiolitis(RB), emphysema(E), bronchial-wall thickening(BWT), expiratory air-trapping(AT), and bronchiectasis(B). Multivariable logistic regression models were used to assess associations of CT features with respiratory symptoms, dyspnea, health status as determined by COPD assessment test, and risk of clinically significant exacerbations during 12 months follow-up.
  
  
  RESULTS
  About 11% of life-time never-smokers demonstrated emphysema on CT scans. Prevalence increased to 30% among smokers with normal lung function and 36%, 50%, and 57% among individuals with mild, moderate or severe/very severe COPD, respectively. Presence of emphysema on CT was associated with chronic cough (OR,2.11; 95%CI,1.4-3.18); chronic phlegm production (OR,1.87; 95% CI,1.27-2.76); wheeze (OR,1.61; 95% CI,1.05-2.48); dyspnoea (OR,2.90; 95% CI,1.41-5.98); CAT score≥10(OR,2.17; 95%CI,1.42-3.30) and risk of ≥2 exacerbations over 12 months (OR,2.17; 95% CI, 1.42-3.0).
  
  
  CONCLUSIONS
  Burden of thoracic CT abnormalities is high among Canadians ≥40 years of age, including never-smokers and smokers with normal lung function. Detection of emphysema on CT scans is associated with pulmonary symptoms and increased risk of exacerbations, independent of smoking or lung function.
authors.affiliation: Center for Heart Lung Innovation, St. Paul's Hospital, University of British Columbia, Vancouver, BC, Canada.
authors.forename: Wan C
authors.initials: WC
authors.lastname: Tan
authors.affiliation: Department of Radiology, St. Paul's Hospital, University of British Columbia, Vancouver, BC, Canada.
authors.forename: Cameron J
authors.initials: CJ
authors.lastname: Hague
authors.affiliation: Department of Radiology, St. Paul's Hospital, University of British Columbia, Vancouver, BC, Canada.
authors.forename: Jonathon
authors.initials: J
authors.lastname: Leipsic
authors.affiliation: Respiratory Epidemiology and Clinical Research Unit, Montreal Chest Institute, McGill University, Montréal, QC, Canada.
authors.forename: Jean
authors.initials: J
authors.lastname: Bourbeau
authors.affiliation: Center for Heart Lung Innovation, St. Paul's Hospital, University of British Columbia, Vancouver, BC, Canada.
authors.forename: Liyun
authors.initials: L
authors.lastname: Zheng
authors.affiliation: Respiratory Epidemiology and Clinical Research Unit, Montreal Chest Institute, McGill University, Montréal, QC, Canada.
authors.forename: Pei Z
authors.initials: PZ
authors.lastname: Li
authors.affiliation: Center for Heart Lung Innovation, St. Paul's Hospital, University of British Columbia, Vancouver, BC, Canada.
authors.forename: Don D
authors.initials: DD
authors.lastname: Sin
authors.affiliation: Center for Heart Lung Innovation, St. Paul's Hospital, University of British Columbia, Vancouver, BC, Canada.
authors.forename: Harvey O
authors.initials: HO
authors.lastname: Coxson
authors.affiliation: Center for Heart Lung Innovation, St. Paul's Hospital, University of British Columbia, Vancouver, BC, Canada.
authors.forename: Miranda
authors.initials: M
authors.lastname: Kirby
authors.affiliation: Center for Heart Lung Innovation, St. Paul's Hospital, University of British Columbia, Vancouver, BC, Canada.
authors.forename: James C
authors.initials: JC
authors.lastname: Hogg
authors.affiliation: Department of Radiology, St. Paul's Hospital, University of British Columbia, Vancouver, BC, Canada.
authors.forename: Rekha
authors.initials: R
authors.lastname: Raju
authors.affiliation: University of British Columbia, Vancouver General Hospital, Institute for Heart and Lung Health, Vancouver, BC, Canada.
authors.forename: Jeremy
authors.initials: J
authors.lastname: Road
authors.affiliation: Division of Respiratory & Critical Care Medicine, Queen's University, Kingston, ON, Canada.
authors.forename: Denis E
authors.initials: DE
authors.lastname: O'Donnell
authors.affiliation: Hospital Laval, Centre de Pneumologie, Institute Universitaire de Cardiologie et de Pneumologie de Quebec, Universite Laval, Quebec, QC, Canada.
authors.forename: Francois
authors.initials: F
authors.lastname: Maltais
authors.affiliation: Division of Respirology, QEII Health Sciences Centre, Dalhousie University, Halifax, Nova Scotia, Canada.
authors.forename: Paul
authors.initials: P
authors.lastname: Hernandez
authors.affiliation: Departments of Medicine and Community Health Sciences, University of Calgary, Calgary, Alberta, Canada.
authors.forename: Robert
authors.initials: R
authors.lastname: Cowie
authors.affiliation: Asthma & Airway Centre, University Health Network, Toronto, ON, Canada.
authors.forename: Kenneth R
authors.initials: KR
authors.lastname: Chapman
authors.affiliation: Division of Respirology, Critical Care and Sleep Medicine, and Airway research Group, University of Saskatchewan, Saskatoon, SK, Canada.
authors.forename: Darcy D
authors.initials: DD
authors.lastname: Marciniuk
authors.affiliation: University of British Columbia, Vancouver General Hospital, Institute for Heart and Lung Health, Vancouver, BC, Canada.
authors.forename: J Mark
authors.initials: JM
authors.lastname: FitzGerald
authors.affiliation: Ottawa Hospital Research Institute, University of Ottawa, Ottawa, ON, Canada.
authors.forename: Shawn D
authors.initials: SD
authors.lastname: Aaron
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002170:Canada / Q000453:epidemiology; D015331:Cohort Studies; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D016017:Odds Ratio; D017063:Outcome Assessment, Health Care; D011159:Population Surveillance; D015995:Prevalence; D029424:Pulmonary Disease, Chronic Obstructive / Q000000981:diagnostic imaging* / Q000453:epidemiology / Q000503:physiopathology*; D012129:Respiratory Function Tests; D057566:Self Report; D012720:Severity of Illness Index; D014057:Tomography, X-Ray Computed