Comparison of the derivation and validation cohorts

Derivation cohortValidation cohortp-value
Age years61±1161±130.9
Male %55390.03
ILD diagnosis 
 CTD59 (28)33 (54)<0.001
 Sarcoidosis43 (20)6 (10)0.06
 IPF62 (29)5 (8)0.007
 CHP16 (8)6 (10)0.5
 NSIP16 (8)6 (10)0.5
 Other ILD14 (7)5 (8)0.7
 mPAP mmHg33±1133±120.8
 PVR Wood units6.0±3.66.9±5.60.3
 Cardiac output L·min-14.3±1.34.1±1.40.6
 PCWP mmHg10±510±50.9
BNP ng·L−1102 (44–266)103 (42–306)0.7
Pulmonary function tests 
 FEV1 L1.6±0.61.6±0.80.5
 FEV1 % pred58±1862±210.3
 FVC L2.0±0.82.0±0.90.7
 FVC % pred60±2065±220.2
 TLCO % pred25±1027±100.2
 KCO % pred52±1754±170.7
 PaO2 kPa7.9±1.98.5±2.10.1
CT scan 
 ILD extent# 20%/>20%14/8619/810.5

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).