Table 3.
Secondary outcomes: time supine, sleep architecture, respiration, user feedback
| PrenaBelt (n=20) |
Sham (n=20) |
PrenaBelt minus sham Difference (95% CI) |
P values | |
| Total sleep time (minutes) | 353 (318–376) | 350 (318–374) | −3.6* (−33.8 to 21.8) | 0.81 |
| Supine sleep (minutes) | 12.3 (0–53.5) | 56.8 (12.4–79.1) | −26.4* (−49.9 to −2.6) | 0.03 |
| Left-lateral sleep (minutes) | 185.6 (102.5) | 176.1 (95.2) | 9.5† (−24.3 to 43.3) | 0.56 |
| Right-lateral sleep (minutes) | 108.9 (110.1) | 101.9 (100.9) | 6.9† (−22.9 to 36.7) | 0.63 |
| Percentage sleep left (%) | 57.0 (26.9) | 52.2 (27.0) | 4.8† (−5.1 to 14.8) | 0.32 |
| Percentage sleep right (%) | 31.3 (28.8) | 29.3 (27.5) | 2.0† (−6.0 to 10.1) | 0.60 |
| Sleep latency (minutes) | 11.7 (6.7–21.9) | 14.5 (7.2–26.2) | 2.0* (−7.2 to 9.4) | 0.65 |
| Sleep efficiency (%) | 81 (76–89) | 83 (79–88) | −1.4* (−5.9 to 3.0) | 0.46 |
| Total arousal index | 11.2 (8.1–18.0) | 12.0 (8.5–15.6) | 0.60* (−1.5 to 3.5) | 0.59 |
| Spontaneous arousal index | 10.5 (5.8) | 10.3 (5.5) | 0.20† (−2.2 to 2.6) | 0.86 |
| PLM arousal index | 0 (0–1.0) | 0.1 (0–0.7) | 0.3* (−1.5 to 16.0) | 0.68 |
| Respiratory arousal index | 0.4 (0–1.1) | 0.4 (0–1.0) | 0.1* (−0.5 to 2.1) | 0.78 |
| Percent stage 1 sleep (%) | 9.1 (5.2) | 9.6 (6.0) | −0.50† (−2.3 to 1.3) | 0.56 |
| Percent stage 2 sleep (%) | 64.5 (7.4) | 61.0 (8.1) | 3.5† (−0.3 to 7.3) | 0.07 |
| Percent stage 3 sleep (%) | 10.9 (8.0) | 11.5 (8.8) | −0.63† (−2.6 to 1.4) | 0.52 |
| Percent REM sleep (%) | 15.5 (6.4) | 18 (4.6) | −2.5† (−5.1 to 0.05) | 0.05 |
| Apnoea–Hypopnea Index | 0.5 (0–1.5) | 0.5 (0–1.5) | −0.14* (−0.8 to 0.4) | 0.51 |
| RERA index | 0 (0–0.1) | 0 (0–0.3) | 0.15* (−0.4 to 4.6) | 0.78 |
| Respiratory Disturbance Index | 0.65 (0–1.5) | 0.55 (0.15–1.75) | 0.2* (−0.6 to 1.2) | 0.67 |
| RDI while supine | 0 (0–0) | 0 (0–1.2) | −1.3* (−11.2 to 2.4) | 0.48 |
| RDI while non-supine | 0.2 (0–1.5) | 0.5 (0–1.75) | −0.05* (−0.85 to 1.0) | 0.92 |
| SpO2 during REM (%) | ||||
| Maximum | 98 (98–99) | 98.5 (98–99) | 0.0* (−1.0 to 0) | 0.28 |
| Mean | 95.8 (1.2) | 96.2 (1.2) | −0.46† (−1.1 to 0.15) | 0.13 |
| Minimum | 92.5 (90.8–94) | 92 (89–94) | 0.5* (−1.0 to 2.5) | 0.40 |
| SpO2 during NREM (%) | ||||
| Maximum | 99.0 (98–100) | 99 (98–100) | 0.5* (−1.0 to 1.5) | 0.46 |
| Mean | 96.1 (0.88) | 96.4 (1.0) | −0.29† (−0.71 to 0.14) | 0.17 |
| Minimum | 92 (91–94) | 92.5 (89–94) | 0.5* (−0.5 to 2.5) | 0.26 |
| Presence of snoring | 15 (75%) | 11 (55%) | 2.4‡ (0.54 to 11.9) | 0.32 |
| Satisfaction (out of 10) | 7.5 (6.0–8.3) | 7.5 (5.5–9.0) | −0.28† (−1.0 to 0.5) | 0.46 |
| Comfort (out of 10) | 9.0 (6.8–9.3) | 9.0 (7.8–10) | −1* (−2.8 to 0) | 0.06 |
| Intention to use (out of 10) | 8.0 (5.8–8.0) | 7.0 (6.0–9.0) | −0.1† (−1.0 to 0.8) | 0.81 |
P-values less than 0.05 are bold text.
Count data (presence of snoring) are presented as frequency (%).
Units for ‘index’ variables are events per hour.
*Non-normally distributed continuous variables and discrete data (satisfaction, comfort and intention to use) are presented as median (IQR), and two-sided paired Wilcoxon signed-rank test is used to test for difference (‘Difference (95% CI)’ is the median of the pairwise differences (pseudomedian) and 95% CI for the pseudomedian).
†Normally distributed continuous variables are reported as mean (SD), and paired t-test is used to test for difference.
‡Fisher’s exact test (‘difference’ is OR).
NREM, non-rapid eye movement; PLM, periodic leg movement; RDI, respiratory disturbance index; REM, rapid eye movement; RERA, respiratory effort-related arousal; SpO2, peripheral oxygen saturation.