Table 1– Baseline characteristics
COPD mean PAP 25–39 mmHgCOPD mean PAP ≥40 mmHgp-value
Subjects n4259
Age years67±1170±90.092
Female45310.130
BMI kg·m−228±827±60.520
Smoking
 Never-smoker25>0.05
 Ex-smoker7883>0.05
 Current smoker2012>0.05
Tobacco pack-years45±2838±280.295
Symptom duration months24 (12–60)24 (12–42)0.788#
Comorbidities
 Diabetes mellitus21290.403
 Systemic hypertension24310.459
 Atrial fibrillation17220.505
 Atrial flutter530.727
 Left ventricular hypertrophy780.807
 Ischaemic heart disease26390.180
 Valvular left heart disease1270.373
 Peripheral vascular disease5140.145
 Chronic kidney disease10140.537
Exercise limitation
 WHO-FC0.016
  III7461
  IV1236
 ISWD m140 (45–195)40 (18–100)0.001#
SpO2 on air %87.8±6.980.5±9.3<0.001
 Decrease in SpO2 during ISWT %-11.2±8.5-7.9±6.20.044
Arterial blood gases
 On air
  PaCO2 mmHg45.0±9.836.0±11.30.010
  PaO2 mmHg56.3±9.845.8±11.30.004
 Entrained oxygen flow L·min−12.7±1.85.3±3.90.017
  PaCO2 mmHg46.5±16.534.5±8.30.005
  PaO2 mmHg72±1866.8±14.30.331
Right heart catheter
 Resting SpO2 %93±494±40.342
 Entrained O2 L·min−10 (0–4)2.0 (0–5.5)0.022#
Mean RAP mmHg8±412±50.001
Mean PAP mmHg32±549±8<0.001
CI L·min·m−23.2±0.82.5±0.7<0.001
PCWP mmHg13±512±50.156
PVR dyn·s·cm−5303±168755±377<0.001
SvO2 %67±863±80.051
Pulmonary function tests
 FEV1 % pred51±2865±230.006
 FVC % pred78±2590±240.022
 FEV1/FVC0.51±0.180.59±0.180.041
DLCO % pred40±2027±130.001
CT scan
 Total emphysema score5 ( 1–15)9.5 (2–18)0.191#
 Total upper zone emphysema3.5 (0–6)5.5 (1–7)0.214#
 Total lower zone emphysema0 (0–3)0.5 (0–4)0.178#
 Total fibrosis score0 (0–2)0 (0–2.5)0.509#
 Total upper zone fibrosis0 (0–0)0 (0–0)0.790#
 Total lower zone fibrosis0 (0–1.5)0 (0–2)0.330#
Pulmonary artery/aorta1.0±0.11.0±0.10.202
Right ventricle/left ventricle1.1±0.41.3±0.40.031
  • Data are presented as %, mean±sd or median (interquartile range), unless otherwise stated. COPD: chronic obstructive pulmonary disease; PAP: pulmonary arterial pressure; BMI: body mass index; WHO-FC: World Health Organization functional class; ISWD: incremental shuttle walking distance; SpO2: arterial oxygen saturation measured by pulse oximetry; PaCO2: arterial carbon dioxide tension; PaO2: arterial oxygen tension; RAP: right atrial pressure; CI: cardiac index by thermodilution method; PCWP: pulmonary capillary wedge pressure; PVR: pulmonary vascular resistance; SvO2: mixed venous oxygen saturation; FEV1: forced expiratory volume in 1 s; % pred: % predicted; FVC: forced vital capacity; DLCO: diffusing capacity of the lung for carbon monoxide; CT: computed tomography. Total emphysema score: sum total of emphysema scores for all six lung zones; total fibrosis score: sum total of fibrosis scores for all six lung zones; upper zone emphysema score: sum total of emphysema for upper zones bilaterally; lower zone emphysema score: sum total of emphysema for lower zones bilaterally; upper zone fibrosis score: sum total of fibrosis for upper zones bilaterally; lower zone fibrosis score: sum total of fibrosis for lower zones bilaterally. #: Mann–Whitney U-test used for non-parametric data.