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Table 1 Baseline characteristics of IPF participants

From: A role for cardiopulmonary exercise testing in detecting physiological changes underlying health status in Idiopathic pulmonary fibrosis: a feasibility study

Characteristic Overall n = 27 Mild n = 19 Moderate n = 8 p value
Age (years) (mean, SD) 75 (± 6.0) 75 (± 6.6) 74 (± 4.3) 0.440
Gender (male n, %) 22, 82% 14, 74% 8, 100% 0.280
Smoking history (n, %)     
 Current 0, 0% 0, 0% 0, 0% 0.552
 Never 10, 37% 9, 47% 1, 12.5%  
 Ex-smoker 17, 63% 10, 53% 7, 87.5%  
BMI (kg/m2) (mean, SD) 28.5 (± 4.5) 28.9 (± 5.0) 27.7 (± 2.9) 0.585
MRC (n)     0.964
 0–1 4 3 1  
 2 16 11 5  
 3 7 5 2  
 4–5 0 0 0  
Antifibrotics (n,%) 9, 33% 5, 26% 4, 50% 0.375
Co-morbidities     n/s
 Gastro-oesophageal reflux 11 6 5  
 Hypertension 10 7 3  
 Coronary artery disease 10 4 6  
 Diabetes 3 1 2  
Lung function parameters (mean, SD)     
FVC (L) 2.96 (± 0.72) 3.11 (± 0.78) 2.61 (± 0.46) 0.050
FVC (% predicted) 91 (± 16.0) 99 (± 10.0) 70 (± 5.1)  < 0.0001
FEV1/FVC ratio 78 (± 7.9) 76 (± 7.8) 82 (± 7.2) 0.080
TLco % predicted 61 (± 9.0) 63 (± 9.5) 57 (± 6.2) 0.055
6MWT (mean, SD) n = 25 n = 18 n = 7  
Distance achieved (m) 350 (± 63.3) 349 (± 66.6) 354 (± 58.6) 0.827
% theoretical distance (m) 78 (± 16.3) 78 (± 16.5) 76 (± 17.0) 0.821
CPET (mean, SD) n = 27 n = 19 n = 8  
VO2 peak/kg (ml/kg/min)* 20.9 (± 3.9) 20.6 (± 4.2) 21.7 (± 3.1) 0.489
VO2/kg at AT (ml/kg/min) 13.6 (± 3.5) 13.8 (± 3.6) 13.0 (± 3.2) 0.585
VE peak (L/min) 69.9 (± 21.1) 69.0 (± 21.7) 72.1 (± 20.9) 0.731
VE peak (% predicted) 74.5 (± 14.4) 71.0 (± 13.9) 82.9 (± 12.4) 0.045
VE/VCO2 at AT 28.2 (± 3.1) 28.7 (± 3.3) 27.2 (± 2.4) 0.201
Minimum O2 saturation during CPET(%) 91 (± 4.7) 91 (± 5.4) 92 (± 2.8) 0.723
Peak work rate (W) 104.8 (± 26.4) 103.6 (± 29.4) 107.6 (± 18.7) 0.673
Peak work (% predicted) 44 (± 8.6) 44 (± 9.5) 43 (± 6.1) 0.565
HR (bpm) 141 (± 21.8) 141 (± 21.2) 139 (± 24.5) 0.793
HR (% predicted) 97 (± 15.1) 98 (± 15.0) 95 (± 16.2) 0.711
BR max (L/min); median (IQR) 26.5 (18.4–32.5) 28.8 (18.8–33.3) 20.4 (12–24.9), n = 7 0.083
K-BILD questionnaire (mean, SD) n = 27 n = 19 n = 8  
 Total 65 (± 9.7) 67 (± 10.3) 60 (± 6.6) 0.058
 Psychological domain 69 (± 17.8) 72 (± 17.8) 61 (± 15.7) 0.128
 Breathlessness and activity domain 56 (± 12.6) 57 (± 13.6) 52 (± 9.4) 0.267
 Chest symptoms domain 78 (± 17.7) 81 (± 18.2) 71 (± 14.6) 0.133
IPF-PROM questionnaire (mean, SD) n = 27 n = 19 n = 8  
 Total 20 (± 4.3) 20 (± 4.6) 21 (± 3.5) 0.337
 Physical breathlessness 5 (± 1.5) 5 (± 1.4) 5 (± 1.5) 0.264
 Psychological breathlessness 5 (± 1.3) 5 (± 1.2) 6 (± 1.5) 0.121
 Well-being 5 (± 2.0) 5 (± 2.2) 5 (± 1.3) 0.662
 Energy 5 (± 1.5) 5 (± 1.7) 5 (± 0.8) 0.565
VAS Cough (cm) (median, (IQR)) 1.7 (0.8–2.8) 1.5 (0.2–2.6) 2.3 (1.4–3.0) 0.135
Bristol VAS breathlessness (cm) 1.9 (0.8–3.3) 1.8 (0.8–3.4) 2.4 (1.1–4.7) 0.630
Bristol VAS fatigue (cm) 3.7 (1.1–5.1) 3.7 (1.1–5.1) 3.8 (1.4–6.3) 0.457
  1. All data shown as mean with standard deviation(SD) unless otherwise stated. All visual analogue scores presented as median with interquartile range (IQR). *Referenced VO2 peak/kg for a 75 year old man would be 26.5 ml/kg/min (based on the linear regression equation male =  − 0.42 × age(years) + 58 (Schneider, Lung 2013 [28]). years years; SD standard deviation; n number; % percentage; FVC forced vital capacity; L litres; FEV1 forced expiratory volume in one second, TLco transfer factor; m metres, HR heart rate; MRC medical research council dyspnoea score; VAS visual analogue score; cm centimetres; bpm beats per minute; W Work; O2 oxygen; L litres; 6MWT 6 min walk test; BMI body mass index; CPET cardiopulmonary exercise test; K-BILD King’s Brief interstitial lung disease questionnaire; IPF-PROM idiopathic pulmonary fibrosis patient reported outcome measure. Unpaired t-test with Welch’s correction was used to compare parametric data of mild and moderate groups, whilst Mann Whitney u was used for non-parametric data. Fisher’s exact test was used to compare categorical data. A p < 0.05 was considered statistically significant