Table 3.
Secondary and Exploratory Outcome Data for the Supplemental Oxygen and Air Arms at Baseline/Run-in and at 2-Week Follow-up
| Oxygen |
Air |
Between-Group Difference, Oxygen vs. Air | P Value | |||
|---|---|---|---|---|---|---|
| Baseline/Run-in | Follow-up | Baseline/Run-in | Follow-up | |||
| Office BP and heart rate recordings | ||||||
| Systolic BP, mm Hg | 132.4 ± 16.7 | 130.9 ± 15.3 | 128.0 ± 13.7 | 134.8 ± 15.5 | −8.3 (−15.3 to −1.3) | 0.02 |
| Diastolic BP, mm Hg | 80.8 ± 9.4 | 79.6 ± 8.2 | 78.9 ± 9.9 | 84.0 ± 9.2 | −6.3 (−11.0 to −1.6) | 0.01 |
| Heart rate, beats/min | 66.3 ± 13.5 | 67.6 ± 13.0 | 65.6 ± 11.9 | 67.8 ± 14.0 | −0.8 (−4.1 to +2.5) | 0.61 |
| Overnight pulse oximetry and sleep study parameters | ||||||
| ODI, per hour | — | 6.4 (4.0 to 14.7) | — | 32.5 (25.6 to 47.0) | −23.8 (−31.0 to −16.3) | <0.001 |
| Mean oxygen saturations, % | — | 96.9 ± 1.2 | — | 92.6 ± 1.8 | +4.3 (+3.6 to +4.9) | <0.001 |
| Time O2 sats < 90%, % | — | 2.0 (0.3 to 3.9) | — | 14.3 (5.9 to 21.2) | −9.8 (−16.7 to −4.3) | <0.001 |
| Heart rate rises < 6 beats/min index, per hour | — | 27.1 (21.4 to 37.4) | — | 31.9 (24.0 to 44.3) | −3.7 (−9.1 to −0.8) | 0.006 |
| Mean heart rate, beats/min | — | 61.5 (53.5 to 64.0) | — | 62.0 (55.4 to 65.1) | −1.2 (−2.8 to +1.1) | 0.12 |
| AHI, per hour | — | 30.4 (23.6 to 42.6) | — | 34.4 (22.7 to 44.4) | −3.6 (−10.2 to +10.1) | 0.98 |
| Measures of sleepiness | ||||||
| ESS, score | 7.0 ± 4.8 | 9.0 ± 4.2 | 6.3 ± 3.8 | 8.8 ± 4.5 | −0.6 (−2.5 to +1.4) | 0.56 |
| OSLER, s | 2,400 (1,285 to 2,400) | 1,746 (770 to 2,400) | 2,400 (1,286 to 2,400) | 2,025 (956 to 2,400) | 0 (−425 to +14) | 0.50 |
| Urinary measurements | ||||||
| Rate of urine production, ml/h | 66.7 (48.6 to 95.8) | 85.1 (59.0 to 111.8) | 66.7 (46.8 to 105.1) | 95.8 (56.3 to 116.7) | +0.4 (−18.2 to +19.0) | 0.97 |
| Normetadrenaline, nmol/μmol | 121.7 (85.2 to 145.3) | 140.0 (116.8 to 186.2) | 107.5 (79.7 to 137.6) | 134.7 (113.7 to 199.7) | −12.8 (−35.3 to +9.6) | 0.25 |
| Metadrenaline, nmol/μmol | 34.1 (28.3 to 44.6) | 37.9 (27.1 to 43.2) | 35.1 (24.8 to 43.6) | 37.3 (26.9 to 46.8) | −0.6 (−6.9 to +5.7) | 0.84 |
| Blood measurements | ||||||
| hsCRP, mg/L | 2.7 (0.9 to 3.5) | 2.0 (0.7 to 3.8) | 1.1 (0.5 to 2.8) | 1.7 (0.9 to 2.6) | −0.4 (−3.7 to +0.6) | 0.12 |
| Venous base excess, mM | +1.6 ± 2.5 | +3.2 ± 2.2 | +3.0 ± 2.3 | +1.5 ± 1.9 | +3.1 (+1.8 to +4.4) | <0.001 |
Definition of abbreviations: AHI = apnea–hypopnea index; BP = blood pressure; CI = confidence interval; ESS = Epworth Sleepiness Scale; hsCRP = high-sensitivity C-reactive protein; ODI = oxygen desaturation index; OSLER = Oxford Sleep Resistance; sats = saturations.
For office BP and heart rate, measures of sleepiness, urinary measurements, and blood measurements, the difference in the change in values from baseline to follow-up was compared, oxygen versus air. For overnight oximetry and home sleep study parameters, the absolute differences in values at follow-up were compared, oxygen versus air. Normetadrenaline and metadrenaline excretions were corrected by urinary creatinine concentrations. Baseline and follow-up data are expressed as mean ± SD or median (interquartile range) and for oxygen–air differences, data are expressed as mean (95% CI, lower limit–upper limit) or median (interquartile range). Differences were compared using paired t tests or Wilcoxon rank tests as appropriate. Bold indicates P < 0.05.