Multivariable analysis for the differences in the ratio of blood vessel volume in vessels <5 mm2 in cross-section (BV5) to total blood vessel volume (TBV) between subjects with lower lobes bronchiectasis and without bronchiectasis using alternate definitions of the disease

Alternate definitionDifference in lower-lobe BV5/TBVsep-value
1) Two or more bronchial paths involved
 Entire cohort−1.80.40<0.0001
 Emphysema status subcohort
  Subjects with emphysema−1.80.570.002
  Subjects without emphysema−1.30.490.009
2) Lack of airway lumen tapering+airway seen within 1 cm of the pleura
 Entire cohort−2.10.580.0003
 Emphysema status subcohort
  Subjects with emphysema−1.90.770.01
  Subjects without emphysema−2.40.800.003

The differences in lower-lobe BV5/TBV×100 are from a multivariable regression model where the presence of bronchiectasis in the lower lobes is the main predictor. Analyses were adjusted for age, sex, race, pack-years smoked, forced expiratory volume in 1 s % predicted, total lung capacity determined by computed tomography % predicted, resting arterial oxygen saturation, percentage of low-attenuation areas below −950 Hounsfield units (%LAA−950) of the lower lobes and coronary artery disease. For the analysis stratified by emphysema of the lower lobes, %LAA−950 was omitted as a covariate.