Baseline characteristics*
| CPAP n=107 n (%) or mean (SD) or median (25; 75 IQR) | NIV n=97 n (%) or mean (SD) or median (25; 75 IQR) | P value† | |
| Age, years | 60 (49; 71) | 65 (56.5; 71.5) | 0.056 |
| Sex, female | 54 (50%) | 61 (63%) | 0.090 |
| Smokers | 33 (31%) | 18 (19%) | 0.052 |
| Smoking, pack/year‡ | 20 (10; 30) | 20 (20; 22.5) | 0.920 |
| Drinkers§ | 8 (7%) | 13 (13%) | 0.249 |
| Alcohol, g‡ | 37 (30.5; 77.5) | 45 (35; 77) | 0.645 |
| BMI, kg/m2 | 42.7 (38.2; 48.8) | 42.9 (38.1; 47.6) | 0.604 |
| Neck circumference, cm | 45 (41; 48) | 44 (42; 47) | 0.578 |
| ESS | 10.6 (5.19) | 11.4 (4.96) | 0.348 |
| FOSQ | 73.3 (21.7) | 74.8 (21.1) | 0.607 |
| SF36-Physical | 34.7 (28.5; 44.8) | 36.7 (27.7; 45.3) | 0.786 |
| SF36-Mental | 45.8 (31.6; 50.1) | 45 (32.7; 53.2) | 0.933 |
| VAWS | 48 (30.8; 66.6) | 50 (37.5; 58.3) | 0.784 |
| Dyspnoea MRC scale ≥2 | 54 (54%) | 61 (63%) | 0.209 |
| Hypertension | 71 (66%) | 69 (71%) | 0.546 |
| Antihypertensive drugs‡ | 2 (1; 2) | 2 (1;2) | 0.532 |
| Systolic BP, mm Hg | 138 (130; 145) | 140 (130; 150) | 0.765 |
| Diastolic BP, mm Hg | 80 (70; 90) | 80 (70; 90) | 0.336 |
| Diabetes | 36 (34%) | 40 (41%) | 0.311 |
| Antidiabetic medications | 34 (32%) | 39 (40%) | 0.243 |
| Dyslipidaemia | 43 (40%) | 47 (48%) | 0.260 |
| Treatment of dyslipidaemia | 37 (35%) | 39 (40%) | 0.469 |
| Stroke | 10 (9%) | 6 (6%) | 0.445 |
| Ischaemic heart disease | 10 (9%) | 8 (8%) | 0.999 |
| Arrhythmia | 6 (6%) | 11 (11%) | 0.204 |
| Chronic heart failure | 13 (12%) | 17 (18%) | 0.325 |
| Leg arteriopathy | 5 (5%) | 5 (5%) | 0.999 |
| Pulmonary hypertension | 9 (8%) | 8 (8%) | 0.999 |
| At least one CVM | 35 (33%) | 33 (34%) | 0.882 |
| CVM | 0 (0;1) | 0 (0; 1) | 0.575 |
| pH | 7.40 (7.38; 7.43) | 7.40 (7.38; 7.42) | 0.440 |
| PaO2, mm Hg | 60 (55; 67.1) | 61 (56.7; 67) | 0.787 |
| PaCO2, mm Hg | 49 (47; 52) | 51 (48; 54) | 0.300 |
| Bicarbonate, mmol/L | 29.5 (28; 32) | 29.8 (27.8; 31.4) | 0.693 |
| FEV1 in % of predicted | 77 (64; 90) | 77 (67.3; 88.5) | 0.728 |
| FVC in % of predicted | 82.4 (20.8) | 77.1 (20.4) | 0.069 |
| 6-MWD in metres | 372.5 (283; 448.5) | 378 (133.4; 450) | 0.770 |
| Polysomnographic parameters¶ | |||
| TST, hours | 5.35 (1.37) | 5.2 (1.23) | 0.519 |
| Sleep efficiency | 72.9 (59.7; 85.3) | 72.2 (61; 84.9) | 0.920 |
| Non-REM 1 and 2, % | 85 (74.6; 91.5) | 85.4 (73; 92.2) | 0.676 |
| Non-REM 3, % | 6 (6; 13.4) | 3.8 (0; 16.2) | 0.342 |
| REM sleep, % | 7 (3.3; 14) | 9.18 (3.1; 14.3) | 0.776 |
| Arousal index | 58.5 (31.7; 85) | 56.5 (32; 75.5) | 0.565 |
| AHI | 68.2 (41.6; 92.4) | 68.7 (48.5; 97.1) | 0.311 |
| ODI | 72.9 (39; 98.2) | 68.8 (44; 94) | 0.700 |
| Mean SpO2 during sleep | 86 (81; 90) | 85 (82; 88) | 0.284 |
| TST with SpO2 <90%, % | 75 (48.7; 94.2) | 79 (51.8; 95.8) | 0.611 |
| Oxygen therapy** | 29 (27%) | 21 (22%) | 0.417 |
| Oxygen therapy flow, L/min‡ | 1.5 (1.3; 2) | 2 (1.1; 2) | 0.519 |
*Data presented as %, median (25; 75 IQR) or mean (SD).
†Non-parametric Mann-Whitney U test for continuous variables and χ2 test for binary variables.
‡Includes only patients who reported to be active smokers or drinkers or patients with hypertension or with oxygen therapy.
§People who drink more than 30 g of alcohol/day in men and 20 g in women.
¶Polysomnography was performed in baseline conditions without CPAP/NIV or oxygen therapy in-place.
**Oxygen therapy was prescribed during the baseline visit.
AHI, apnoea–hypopnoea index; BMI, body mass index; BP, blood pressure; CVM, sum of cardiovascular morbidities; EES, Epworth Sleepiness Scale;FOSQ, Functional Outcomes of Sleep Questionnaire; MRC, Medical Research Council; 6-MWD, 6 min walk distance; NIV, non-invasive ventilation; ODI, 3% oxygen desaturation index;SpO2, oxygen saturation by pulse oximetry; TST, total sleep time; VAWS, visual analogical well-being scale.