Polysomnographic sleep characteristics according to apnoea-hypopnoea index stratum
| Complete cohort (n=234) | AHI<5 (n=77) | 5≤AHI <10 (n=84) | 10≤AHI<15 (n=33) | AHI≥15 (n=36) | |
|---|---|---|---|---|---|
| PSG total sleep time (h) | 6.7 (1.4) | 6.7 (1.6) | 6.9 (1.1) | 6.5 (1.4) | 6.2 (1.6) |
| N1 sleep (min) | 43.4 (21.1) | 38.5 (21.3) | 44.4 (19.6) | 46.4 (26.0) | 48.6 (18.1) |
| N2 sleep (min) | 212.6 (62.1) | 219.7 (68.6) | 212.1 (55.6) | 215.9 (59.7) | 195.8 (63.1) |
| N3 sleep (min) | 71.1 (32.4) | 72.3 (30.7) | 79.8 (30.8) | 57.9 (29.0) | 61.3 (36.5) |
| REM sleep (min) | 73.8 (26.7) | 73.6 (29.0) | 78.3 (24.0) | 70.6 (27.4) | 67.0 (26.4) |
| Obstructive apnoea index (events/h) | 0.1 (0.6) | 0 | 0.03 (0.1) | 0.04 (0.1) | 0.7 (1.4) |
| Obstructive hypopnoea index (events/h) | 8.5 (8.0) | 2.9 (1) | 6.2 (1.7) | 11.7 (1.9) | 20.6 (7.1) |
| Obstructive hypopnoeas associated with microarousals—index (events/h) | 6.3 (5.6) | 2.1 (0.8) | 4.7 (1.4) | 9.4 (2.3) | 15.5 (7.0) |
| 4% oxygen desaturation index (events/h) | 0.8 (2.5) | 0.13 (0.4) | 0.44 (0.7) | 0.38 (0.8) | 3.44 (5.4) |
| Oxygen saturation nadir (%) | 91 (6) | 92 (2) | 91 (5) | 88 (8) | 88 (9) |
| Microarousal index (events/h) | 27.1 (10.6) | 22.1 (7.6) | 25 (8.5) | 32.0 (8) | 37.4 (13) |
Values are means (SD) or numbers (%).
p Values represent statistical tests by analysis of variance (ANOVA) for continuous variables and Fisher's exact test for non-parametrical and χ2 test for parametrical categorical variables.
AHI, apnoea-hypopnoea index; PSG, polysomnography; REM, rapid eye movement.