title: Cross-sectional analysis of the utility of pulmonary function tests in predicting emphysema in ever-smokers.
abstract: Emphysema is largely an under-diagnosed medical condition that can exist in smokers in the absence of airway obstruction. We aimed to determine the sensitivity and specificity of pulmonary function tests (PFTs) in assessing emphysema using quantitative CT scans as the reference standard. We enrolled 224 ever-smokers (current or former) over the age of 40. CT of thorax was used to quantify the low attenuation area (% emphysema), and to measure the standardized airway wall thickness. PFTs were used individually and in combination to predict their ability to discriminate radiographic emphysema. Significant emphysema (>7%) was detected in 122 (54%) subjects. Twenty six (21%) emphysema subjects had no evidence of airflow obstruction (FEV(1)/FVC ratio <70%), while all subjects with >23% emphysema showed airflow obstruction. The sensitivity and specificity of spirometry for detecting radiographic emphysema were 79% and 75%, respectively. Standardized airway wall thickness was increased in subjects with airflow obstruction, but did not correlate with emphysema severity. In this cohort of lifetime ever-smokers, PFTs alone were inadequate for diagnosing emphysema. Airway wall thickness quantified by CT morphometry was associated with airflow limitation, but not with emphysema indicating that the heterogeneous nature of lung disease in smokers may represent distinct phenotypes.
authors.affiliation: Division of Pulmonary, Critical Care, and Sleep Medicine, Department of Medicine, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, USA. hesselba@bcm.tmc.edu
authors.forename: Sean E
authors.initials: SE
authors.lastname: Hesselbacher
authors.forename: Robert
authors.initials: R
authors.lastname: Ross
authors.forename: Matthew B
authors.initials: MB
authors.lastname: Schabath
authors.forename: E O'Brian
authors.initials: EO
authors.lastname: Smith
authors.forename: Sarah
authors.initials: S
authors.lastname: Perusich
authors.forename: Nadia
authors.initials: N
authors.lastname: Barrow
authors.forename: Pamela
authors.initials: P
authors.lastname: Smithwick
authors.forename: Manoj J
authors.initials: MJ
authors.lastname: Mammen
authors.forename: Harvey
authors.initials: H
authors.lastname: Coxson
authors.forename: Natasha
authors.initials: N
authors.lastname: Krowchuk
authors.forename: David B
authors.initials: DB
authors.lastname: Corry
authors.forename: Farrah
authors.initials: F
authors.lastname: Kheradmand
mesh_terms: D000368:Aged; D000402:Airway Obstruction / Q000473:pathology; D001980:Bronchi / Q000473:pathology; D003430:Cross-Sectional Studies; D004646:Emphysema / Q000175:diagnosis* / Q000209:etiology; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D011446:Prospective Studies; D012129:Respiratory Function Tests; D012907:Smoking / Q000009:adverse effects; D014057:Tomography, X-Ray Computed