Single and composite predictor variables and their correlations
| GOLD | Correlation | ||||
| New variables | 2 (n=40) | 3 (n=30) | 4 (n=31) | t | p* |
| Obstruction (-FEV1%) | −1.0 (0.5) | 0.2 (0.4) | 1.1 (0.4) | 0.79 | 0.0001 |
| Emphysema (residual volume %, RV/TLC) | −1.4 (1.1) | −0.1 (1.9) | 1.9 (1.1) | 0.56 | 0.0001 |
| Afterload (mPAP, PVR,- PAC, RV wall) | −1.5 (1.7) | −0.7 (2.6) | 2.7 (2.9) | 0.45 | 0.0001 |
*p<0.05, p values refer to Kendall’s t correlation for trend between variables.
FEV1%, forced expiratory volume in 1 s % predicted; GOLD, Global Initiative for Chronic Obstructive Lung Disease; mPAP, mean pulmonary artery pressure; PAC, pulmonary arterial compliance; PVR, pulmonary vascular resistance; RV/TLC, residual volume/total lung capacity; RV wall, right ventricle wall thickness; t, Kendalls t correlation.