title: Obesity and extent of emphysema depicted at CT.
abstract: OBJECTIVE
  To investigate the underlying relationship between obesity and the extent of emphysema depicted at CT.
  
  
  METHODS
  A dataset of 477 CT examinations was retrospectively collected from a study of chronic obstructive pulmonary disease (COPD). The low attenuation areas (LAAs; ≤950 HU) of the lungs were identified. The extent of emphysema (denoted as %LAA) was defined as the percentage of LAA divided by the lung volume. The association between log-transformed %LAA and body mass index (BMI) adjusted for age, sex, the forced expiratory volume in one second as percent predicted value (FEV1% predicted), and smoking history (pack years) was assessed using multiple linear regression analysis.
  
  
  RESULTS
  After adjusting for age, gender, smoking history, and FEV1% predicted, BMI was negatively associated with severe emphysema in patients with COPD. Specifically, one unit increase in BMI is associated with a 0.93-fold change (95% CI: 0.91-0.96, p<0.001) in %LAA; the estimated %LAA for males was 1.75 (95% CI: 1.36-2.26, p<0.001) times that of females; per 10% increase in FEV1% predicated is associated with a 0.72-fold change (95% CI: 0.69-0.76, p<0.001) in %LAA.
  
  
  CONCLUSIONS
  Increasing obesity is negatively associated with severity of emphysema independent of gender, age, and smoking history.
authors.affiliation: Imaging Research Center, Department of Radiology, University of Pittsburgh, PA, USA.
authors.forename: S
authors.initials: S
authors.lastname: Gu
authors.affiliation: Division of Biostatistics, University of Texas School of Public Health, TX, USA.
authors.forename: R
authors.initials: R
authors.lastname: Li
authors.affiliation: Imaging Research Center, Department of Radiology, University of Pittsburgh, PA, USA.
authors.forename: J K
authors.initials: JK
authors.lastname: Leader
authors.affiliation: School of Electrical and Computer Engineering, University of Oklahoma, Norman, OK, USA.
authors.forename: B
authors.initials: B
authors.lastname: Zheng
authors.affiliation: Department of Medicine, University of Pittsburgh, Pittsburgh, PA, USA.
authors.forename: J
authors.initials: J
authors.lastname: Bon
authors.affiliation: Imaging Research Center, Department of Radiology, University of Pittsburgh, PA, USA.
authors.forename: D
authors.initials: D
authors.lastname: Gur
authors.affiliation: Department of Medicine, University of Pittsburgh, Pittsburgh, PA, USA.
authors.forename: F
authors.initials: F
authors.lastname: Sciurba
authors.affiliation: Department of Radiology, The First Affiliated Hospital of Xi'an Jiaotong University, Xi'an, Shaanxi, China.
authors.forename: C
authors.initials: C
authors.lastname: Jin
authors.affiliation: Imaging Research Center, Department of Radiology, University of Pittsburgh, PA, USA; Department of Bioengineering, University of Pittsburgh, Pittsburgh, PA, USA. Electronic address: jip13@pitt.edu.
authors.forename: J
authors.initials: J
authors.lastname: Pu
mesh_terms: D000368:Aged; D015992:Body Mass Index; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009765:Obesity / Q000150:complications*; D010414:Pennsylvania; D011656:Pulmonary Emphysema / Q000150:complications* / Q000000981:diagnostic imaging*; D012129:Respiratory Function Tests; D012307:Risk Factors; D012737:Sex Factors; D011795:Surveys and Questionnaires; D014057:Tomography, X-Ray Computed / Q000379:methods*