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 definition | Difference in lower-lobe BV5/TBV | se | p-value |
| 1) Two or more bronchial paths involved | |||
| Entire cohort | −1.8 | 0.40 | <0.0001 |
| Emphysema status subcohort | |||
| Subjects with emphysema | −1.8 | 0.57 | 0.002 |
| Subjects without emphysema | −1.3 | 0.49 | 0.009 |
| 2) Lack of airway lumen tapering+airway seen within 1 cm of the pleura | |||
| Entire cohort | −2.1 | 0.58 | 0.0003 |
| Emphysema status subcohort | |||
| Subjects with emphysema | −1.9 | 0.77 | 0.01 |
| Subjects without emphysema | −2.4 | 0.80 | 0.003 |
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.