TABLE 4.
Comparison of the derivation and validation cohorts
| Derivation cohort | Validation cohort | p-value | |
| Subjects | 210 | 61 | |
| Age years | 61±11 | 61±13 | 0.9 |
| Male % | 55 | 39 | 0.03 |
| ILD diagnosis | |||
| CTD | 59 (28) | 33 (54) | <0.001 |
| Sarcoidosis | 43 (20) | 6 (10) | 0.06 |
| IPF | 62 (29) | 5 (8) | 0.007 |
| CHP | 16 (8) | 6 (10) | 0.5 |
| NSIP | 16 (8) | 6 (10) | 0.5 |
| Other ILD | 14 (7) | 5 (8) | 0.7 |
| RHC | |||
| mPAP mmHg | 33±11 | 33±12 | 0.8 |
| PVR Wood units | 6.0±3.6 | 6.9±5.6 | 0.3 |
| Cardiac output L·min-1 | 4.3±1.3 | 4.1±1.4 | 0.6 |
| PCWP mmHg | 10±5 | 10±5 | 0.9 |
| BNP ng·L−1 | 102 (44–266) | 103 (42–306) | 0.7 |
| Pulmonary function tests | |||
| FEV1 L | 1.6±0.6 | 1.6±0.8 | 0.5 |
| FEV1 % pred | 58±18 | 62±21 | 0.3 |
| FVC L | 2.0±0.8 | 2.0±0.9 | 0.7 |
| FVC % pred | 60±20 | 65±22 | 0.2 |
| TLCO % pred | 25±10 | 27±10 | 0.2 |
| KCO % pred | 52±17 | 54±17 | 0.7 |
| PaO2 kPa | 7.9±1.9 | 8.5±2.1 | 0.1 |
| CT scan | |||
| ILD extent# 20%/>20% | 14/86 | 19/81 | 0.5 |
Data are presented as n, mean±sd or median (interquartile range), unless otherwise stated. ILD: interstital lung disease; CTD: connective tissue disease; IPF idiopathic pulmonary fibrosis; CHP: chronic hypersensitivity pneumonitis; NSIP: nonspecific interstitial pneumonia; RHC: right heart catheterisation; mPAP: mean pulmonary pressure; PVR: pulmonary vascular resistance; PCWP: pulmonary capillary wedge pressure; BNP: brain natriuretic peptide; FEV1: forced expiratory volume in 1 s; FVC: forced vital capacity; TLCO: transfer factor of the lung for carbon monoxide; KCO: transfer coefficient of the lung for carbon monoxide; PaO2: arterial oxygen tension (by capillary blood gas analysis); CT: computed tomography. #: formal scoring of severity on CT (see methods section).