Table 3.
Polysomnography (PSG) Parameters by Normal Spirometry, Restrictive or Obstructive/Mixed Impairments on Spirometry
| Polysomnography Data | Polysomnography Parameters | Normal Spirometry (n=122) | Restrictive Impairment (n=95) | p-value | Obstructive/Mixed Impairments (n=31) | p-value |
|---|---|---|---|---|---|---|
| Sleep related variables | Sleep latency | 13 (4, 33) | 18 (4.25, 33.5) | 0.187 | 16.15 (4, 45) | 0.436 |
| REM latency | 123 (72.5, 179.5) | 124 (67, 230) | 0.949 | 119 (75, 156.5) | 0.866 | |
| Wake after sleep onset | 53.6 (31.9, 100.75) | 75.5 (39.9, 141) | 0.085 | 77.1 (53, 157) | 0.208 | |
| Sleep efficiency | 84.15 (73.9, 89.3) | 78.85 (67.4, 90) | 0.026* | 77.75 (62.1, 86.7) | 0.093 | |
| Sleep efficiency <80% | 48 (39%) | 47 (52%) | 0.063 | 18 (60%) | 0.044* | |
| Total sleep time | 388 (344.5, 455) | 396.5 (334.9, 480.9) | 0.617 | 389 (330.5, 442.5) | 0.874 | |
| Architecture | N1 (%) | 11.75 (7, 18.2) | 11.3 (5.45, 21.3) | 0.794 | 10.2 (5.6, 20) | 0.572 |
| N2 (%) | 57.05 (50.3, 65.2) | 61 (51.2, 76.9) | 0.086 | 61.85 (53.8, 69.7) | 0.143 | |
| N3 (%) | 7.9 (2.3, 14.4) | 5 (0, 11.7) | 0.124 | 7.8 (2.4, 14.3) | 0.971 | |
| REM (%) | 18.85 (12.6, 23.7) | 13.45 (7, 18.8) | <0.001* | 15.9 (9.8, 21.4) | 0.203 | |
| Arousals | Respiratory arousal index | 11.8 (3.3, 25.3) | 9.7 (3.4, 30.4) | 0.579 | 14.6 (6.1, 18) | 0.539 |
| Spontaneous arousal index | 3.35 (1.3, 6.3) | 2.65 (1.1, 6) | 0.300 | 3 (1.9, 5.2) | 0.690 | |
| Total arousal index | 22.75 (14.2, 37.3) | 27.4 (13.3, 44.9) | 0.142 | 24.7 (14.9, 31.4) | 0.752 | |
| Apnoea-hypopnea index | Total | 21.45 (8.2, 45.8) | 29.3 (12.8, 65) | 0.176 | 31 (13.7, 50.3) | 0.262 |
| NREM | 19.15 (6.25, 47.1) | 27.4 (8.6, 62.6) | 0.167 | 23.25 (16.1, 56.6) | 0.602 | |
| REM | 32.05 (8.5, 62.55) | 52.2 (25.1, 73.2) | 0.010* | 55.1 (21.5, 74.5) | 0.047* | |
| Obstructive sleep apnoea | No | 105 (86%) | 88 (93%) | 0.651 | 28 (90%) | 0.329 |
| Mild | 29 (28%) | 23 (26%) | 5 (18%) | |||
| Moderate | 25 (24%) | 19 (22%) | 7 (25%) | |||
| Severe | 51 (49%) | 46 (52%) | 16 (57%) | |||
| Oxygen saturation | Total | 94 (93, 96) | 93 (91, 96) | 0.136 | 92 (90, 94) | 0.040* |
| Wake | 95 (94, 96) | 95 (92, 96) | 0.999 | 94 (92, 95) | 0.192 | |
| NREM | 94 (93, 96) | 93 (91, 96) | 0.122 | 92 (89, 94) | 0.033* | |
| REM | 94 (91, 96) | 92 (87, 95) | 0.038* | 92.5 (87, 94) | 0.146 | |
| Nadir | 82 (75, 88) | 77 (67, 84) | 0.018* | 78 (69, 85) | 0.188 | |
| Continuous positive airway pressure (CPAP) | Trialled CPAP | 57 (54%) | 60 (68%) | 0.050* | 16 (57%) | 0.787 |
| CPAP > 30 days | 36 (63%) | 36 (60%) | 0.726 | 6 (38%) | 0.073 | |
| Days used (%) | 53.35 (12.2, 97.5) | 20.55 (5.25, 86.35) | 0.081 | 20.85 (7.8, 28.3) | 0.430 | |
| Average hours used | 5.53 (3.53, 7.15) | 4.4 (3.17, 6.34) | 0.213 | 3.17 (1.56, 5.32) | 0.418 | |
| Days used >4 hours (%) | 44.15 (10.55, 82.5) | 12.5 (2.75, 55) | 0.009* | 8.3 (1.1, 22.8) | 0.172 | |
| Adherent | 14 (39%) | 8 (22%) | 0.129 | 1 (17%) | 0.313 |
Notes: Data were median (interquartile range) or number (%). p-values obtained via univariate quantile regression for continuous outcomes and univariate logistic regression for binary outcomes, utilising “normal spirometry” as baseline reference. Fishers exact test was used for obstructive sleep apnoea presence and severity. *Indicates significance at p<0.05.
Abbreviations: N1/N2/N3, non-rapid eye movement stages 1, 2, 3; NREM, Non-Rapid eye movement; REM, Rapid eye movement.