Table 2.
Effect of Treatment on Sleep Characteristics for CPAP versus Oral Placebo Groups*
| CPAP Group (n = 26) |
Oral Placebo Group (n = 12) |
|||||
|---|---|---|---|---|---|---|
| Variable | Baseline | Change after 2 Weeks | Baseline | Change after 2 Weeks | Treatment Difference | P Value |
| Total sleep time, h | 6.7 (6.5 to 7.0) | −0.16 (−0.33 to 0.01) | 6.9 (6.7 to 7.2) | −0.17 (−0.40 to 0.05) | 0.01 (−0.27 to 0.29) | 0.95 |
| Sleep efficiency, % | 84.1 (80.7 to 87.4) | −1.7 (−3.5 to 0.2) | 86.7 (83.6 to 89.9) | −2.2 (−4.7 to 0.3) | 0.5 (−2.6 to 3.6) | 0.74 |
| AHI, events/h | 34.2 (24.3 to 44.1) | −31.6 (−40.0 to −23.2) | 39.0 (24.4 to 53.5) | 2.3 (−9.0 to 13.7) | −33.9 (−48.1 to −19.8) | <0.001 |
| ODI (3%), events/h | 22.5 (14.7 to 30.3) | −21.3 (−28.1 to −14.5) | 29.9 (16.0 to 43.9) | 1.6 (−7.5 to 10.8) | −22.9 (−34.4 to −11.5) | <0.001 |
| Oxygen saturation < 90%, min | 55.0 (25.8 to 84.2) | −49.7 (−72.9 to −26.5) | 62.3 (19.9 to 104.7) | 9.9 (−21.4 to 41.2) | −59.6 (−8.5 to −20.7) | 0.003 |
| Microarousal index, events/h | 32.0 (24.0 to 39.9) | −19.7 (−26.9 to −12.6) | 36.6 (22.6 to 50.6) | 1.3 (−8.4 to 11.0) | −21.0 (−33.1 to −9.0) | 0.001 |
Definition of abbreviations: AHI = apnea–hypopnea index; CPAP = continuous positive airway pressure; ODI = oxygen desaturation index.
Data are mean (95% confidence interval). Sleep variables were derived from the average of the three consecutive nights of polysomnographic recordings during baseline testing (i.e., baseline) and the three consecutive nights of polysomnographic recordings after 2 weeks of treatment during post-treatment testing (i.e., post-treatment). Change after 2 weeks (i.e., treatment effect) was calculated from the regression models as the post-treatment – baseline effect for each treatment group. Treatment difference between the two groups was also calculated from the regression models as the CPAP − oral placebo 2-week changes (i.e., the interaction effect from the model). P values for the treatment difference are from the test of the treatment group–by-time interaction using linear mixed model approach.
All available data were used in the analyses (see online supplement for further details).