TABLE 1.
Baseline characteristics of the study cohort by categories of hypoxic burden (HB) and treatment allocation
| Usual care | CPAP treatment | |||
| Low HB (n=187) | High HB (n=178) | Low HB (n=177) | High HB (n=185) | |
| Clinical data | ||||
| Demographic/anthropometric | ||||
| Age (years) | 60.0 (53.0–66.0) | 59.0 (53.0–68.0) | 60.0 (53.0–67.0) | 58.0 (52.0–65.0) |
| Sex | ||||
| Male | 161 (86.1) | 151 (84.8) | 143 (80.8) | 159 (85.9) |
| Female | 26 (13.9) | 27 (15.2) | 34 (19.2) | 26 (14.1) |
| BMI (kg·m−2) | 28.3 (25.7–30.8) | 30.1 (27.9–32.8) | 27.8 (25.5–30.8) | 29.4 (26.8–33.1) |
| Smoking status | ||||
| Never | 46 (24.6) | 40 (22.5) | 41 (23.2) | 46 (24.9) |
| Former | 50 (26.7) | 53 (29.8) | 45 (25.4) | 47 (25.4) |
| Current | 91 (48.7) | 85 (47.8) | 91 (51.4) | 92 (49.7) |
| Drinking status | ||||
| Never | 142 (78.9) | 132 (75.9) | 124 (71.3) | 138 (76.2) |
| Former | 2 (1.11) | 2 (1.15) | 1 (0.57) | 1 (0.55) |
| Current | 36 (20.0) | 40 (23.0) | 49 (28.2) | 42 (23.2) |
| Comorbidities | ||||
| Diabetes | 38 (20.3) | 50 (28.1) | 52 (29.4) | 54 (29.2) |
| Hypertension | 95 (50.8) | 111 (62.4) | 97 (54.8) | 105 (56.8) |
| Dyslipidaemia | 104 (55.6) | 101 (56.7) | 110 (62.1) | 109 (58.9) |
| Chronic pneumopathy | 13 (6.95) | 14 (7.87) | 11 (6.21) | 10 (5.41) |
| Previous CVD | 29 (15.5) | 42 (23.6) | 33 (18.6) | 37 (20.0) |
| Medication use | ||||
| Insulin | 7 (3.74) | 11 (6.18) | 6 (3.39) | 13 (7.03) |
| Oral antidiabetic drugs | 30 (16.0) | 42 (23.6) | 37 (20.9) | 48 (25.9) |
| ACE inhibitors | 41 (21.9) | 47 (26.4) | 40 (22.6) | 38 (20.5) |
| β-blockers | 37 (19.8) | 37 (20.8) | 28 (15.8) | 40 (21.6) |
| Diuretic agents | 30 (16.0) | 38 (21.3) | 35 (19.8) | 34 (18.4) |
| Calcium-channel blockers | 20 (10.7) | 36 (20.2) | 23 (13.0) | 22 (11.9) |
| Angiotensin II receptor blockers | 24 (12.8) | 30 (16.9) | 28 (15.8) | 35 (18.9) |
| Lipid-lowering drugs | 60 (32.1) | 69 (38.8) | 67 (37.9) | 78 (42.2) |
| Antiplatelet drugs | 39 (20.9) | 43 (24.2) | 40 (22.6) | 42 (22.7) |
| Anticoagulants | 9 (4.81) | 8 (4.49) | 7 (3.95) | 8 (4.32) |
| Sleep data | ||||
| AHI (events·h−1) | 22.0 (17.2–33.0) | 42.0 (32.0–55.5) | 23.0 (18.2–29.4) | 44.0 (30.0–59.0) |
| ODI (events·h−1) | 19.1 (14.4–26.7) | 41.2 (32.6–54.3) | 18.0 (12.8–24.6) | 37.7 (25.6–52.6) |
| Mean SaO2 (%) | 93.7 (92.3–94.9) | 92.4 (90.8–93.6) | 93.3 (92.0–94.4) | 92.7 (91.3–93.6) |
| Minimum SaO2 (%) | 87.0 (82.0–88.0) | 82.0 (76.0–85.0) | 85.0 (81.0–88.0) | 82.0 (78.0–85.0) |
| TSat90 (%) | 0.75 (0.10–3.65) | 8.95 (2.68–27.3) | 1.30 (0.20–6.40) | 6.60 (1.60–22.0) |
| HB (%min·h−1) | 50.6 (40.6–61.2) | 106 (85.0–142) | 53.3 (43.3–63.1) | 102 (84.4–139) |
| Somnolence (ESS) | 4.00 (3.00–6.00) | 5.00 (4.00–8.00) | 5.00 (3.00–6.00) | 5.00 (3.00–8.00) |
Data are presented as median (interquartile range) or n (%). CPAP: continuous positive airway pressure; BMI: body mass index; CVD: cardiovascular disease; ACE: angiotensin-converting enzyme; AHI: apnoea–hypopnoea index; ODI: oxygen desaturation index; SaO2: arterial oxygen saturation; TSat90: percentage of total sleep time with SaO2 <90%; ESS: Epworth Sleepiness Scale. The pre-intervention HB was categorised as “low” or “high” based on the median value (≤73.1%min·h−1 or >73.1%min·h−1, respectively).