Results of sleep study according to subclinical sleep apnoea*
| Characteristic n=1255 | REI<5 n=1150 (92%) | REI 5–14 n=105 (8%) | p Value† |
|---|---|---|---|
| REI | 1 (0–2) | 8 (6–10) | |
| Oxygen desaturation index | 1 (0–2) | 8 (6–11) | <0.0001 |
| Oxygen desaturation index ≥5 (%) | 36 (2%) | 88 (71%) | <0.0001 |
| Mean night-time SpO2 (%) | 95 (94–96) | 93 (92–95) | <0.0001 |
| Per cent of time with SpO2<90% (%) | 0.2 (0–1.2) | 2.8 (0.6–10.5) | <0.0001 |
| Apnoeas per hour | 0 (0–1) | 2 (1–4) | <0.0001 |
| Hypopnoeas per hour | 0 (0–1) | 5 (3–6) | <0.0001 |
| Sleep duration (hours) | 7.3 (6.5–8.0) | 7.3 (6.3–8.0) | 0.8 |
| Mean heart rate (bpm) | 62 (57–68) | 62 (58–71) | 0.13 |
| Mean breathing rate (breaths/min) | 13 (10–15) | 12 (9–14) | 0.01 |
Values are median (IQRs), counts or percentages.
*Subclinical sleep apnoea was defined as REI≥5, but <15.
†Based on Kruskal-Wallis tests for continuous variables.
REI, respiratory event index; SpO2, blood oxygen saturation.