Normal exercise capacity (n=34) | Reduced exercise capacity (n=41) | p-value | |
Male, n (%) | 16 (47) | 27 (65) | 0.101 |
Age, years | 58±10 | 56±13 | 0.482 |
BMI, kg·m−2 | 29.2±4.0 | 28.0±5.1 | 0.309 |
Smoking status never/current/ex-smoker, n (%) | 21/4/9 (62/12/26) | 28/10/3 (68/24/8) | 0.700 |
FEV1, % pred | 107±19 | 102±15 | 0.170 |
FVC, % pred | 103±18 | 98±13 | 0.215 |
DLCO#, % pred | 74±14 | 69±13 | 0.175 |
KCO, % pred | 83±16 | 85±14 | 0.630 |
Alveolar volume, % pred | 89±13 | 83±14 | 0.063 |
CT abnormal/total, n (%) | 19/30 (63) | 24/41 (58) | 0.683 |
CT-SS¶ | 16.0±9.2 | 18.6±10.7 | 0.616 |
%V-RPI¶ | 20 (15–45) | 17 (15–40) | 0.611 |
mMRC (0/1/2/3/4) | 15/13/6/0/0 | 14/18/9/0/0 | 0.672 |
V′O2 peak, % pred | 97±9 | 72±9 | <0.001 |
V′O2 peak absolute, mL·min−1·kg−1 | 22.1±5.5 | 18.3±4.9 | <0.001 |
Work peak, % pred | 97±19 | 76±13 | <0.001 |
Anaerobic threshold, %V′O2 max predicted | 62±13 | 48±9 | <0.001 |
V′O2/work slope, mL·min−1·W−1 | 11.0±1.2 | 9.9±1.3 | <0.001 |
Respiratory exchange ratio at peak | 1.18±0.09 | 1.22±0.11 | 0.121 |
Heart rate reserve, % | 10±11 | 16±12 | 0.040 |
Heart rate peak, bpm | 145±19 | 138±22 | 0.136 |
Oxygen pulse peak, % pred | 110±15 | 85±19 | <0.001 |
Ventilation peak, min−1 | 67±21 | 58±18 | 0.068 |
V′E/V′CO2 slope, L·L−1 | 28.1±3.2 | 28.7±3.1 | 0.453 |
V′E/V′CO2 slope >30, n (%) | 5 (15) | 6 (15) | 0.993 |
Alveolar–arterial gradient for O2 at peak+, mmHg | 26 (19–31) | 26 (16–31) | 0.719 |
PaCO2 at peak+, mmHg | 35±4 | 35±4 | 0.955 |
Lactate at peak+, mmol·L−1 | 7.5±2.7 | 7.1±2.5 | 0.464 |
Borg scale of dyspnoea at peak | 4.0±2.3 | 3.5±2.3 | 0.373 |
Borg scale of perceived exertion at peak | 5.3±2.0 | 5.5±2.0 | 0.638 |
All quantitative data are presented as mean±sd or median (interquartile range), unless otherwise specified. Values presented in bold type refer to p<0.05. Reduced exercise capacity when peak oxygen consumption (V′O2) <85% predicted. #: diffusing capacity of the lung for carbon monoxide (DLCO) available for 32 patients with normal exercise capacity and 37 patients with reduced exercise capacity, respectively; ¶: computed tomography (CT) imaging available for 30 patients with normal exercise capacity and 41 with reduced exercise capacity; +: blood gas analysis data available for 33 patients with normal exercise capacity and 34 with reduced exercise capacity. BMI: body mass index; FEV1: forced expiratory volume in 1 s; FVC: forced vital capacity; KCO: carbon monoxide transfer coefficient; CT-SS: CT severity score; %V-RPI: visual percentage of residual parenchymal involvement; mMRC: modified Medical Research Council scale for dyspnoea; V′E: ventilation; V′CO2: carbon dioxide output; PaCO2: partial arterial pressure for carbon dioxide.