Summary of mixed models comparing the effects of humidified CPAP with sham CPAP and effects of order, compliance, and interactions
| Outcome measurement (and maximum score or standard unit size) | Baseline Mean (SE) | Placebo Mean (SE) | CPAP Mean (SE) | Net effect(95% CI) | Effect size | CPAP usage(p value) |
|---|---|---|---|---|---|---|
| ModMWT, Modified Maintenance of Wakefulness test; FOSQ, Functional Outcomes of Sleepiness Scale; SF-36, Short Form 36 Question version of the Medical Outcomes Survey; HADS, Hospital Anxiety and Depression Scale; RT, reaction time. | ||||||
| Measures (maximum score) with mean (SE) values at baseline and for the effects of CPAP and placebo. *p<0.05; **p<0.01; ***p<0.001 compared with baseline. A positive net effect indicates that CPAP outperformed sham CPAP and negative effect sizes indicate that placebo outperformed CPAP. CPAP usage column indicates simple dose-response relationships. Only the Vitality subscale of the SF-36 and the PVT mean RT exhibited any order effect. Mean (SE) values are derived from within the mixed models. Baseline values are from the first day of testing. | ||||||
| Epworth Scale (24) | 12.5 (0.8) | 12.0 (0.7) | 9.7 (0.7)*** | 2.4 (0.6 to 4.2) | 0.58 | 0.04 |
| ModMWT (latency, min) | 20.9 (2.5) | 17.9 (2.0) | 23.1 (2.0) | 5.2 (−0.6 to 11) | 0.40 | 0.09 |
| FOSQ Total (16) | 12.6 (0.3) | 13.3 (0.3) | 13.6 (0.3)** | 0.3 (−0.5 to 1.1) | 0.14 | 0.96 |
| Activity (4) | 3.0 (0.1) | 3.3 (0.1)* | 3.3 (0.1)** | 0.1 (−0.1 to 0.3) | 0.02 | 0.82 |
| Social outcomes (4) | 3.2 (0.1) | 3.5 (0.1)* | 3.7 (0.1)** | 0.2 (−0.2 to 0.5) | 0.17 | 0.20 |
| Vigilance (4) | 3.0 (0.1) | 3.1 (0.1) | 3.2 (0.1) | 0.1 (−0.2 to 0.3) | 0.13 | 0.05 |
| General product (4) | 3.3 (0.1) | 3.4 (0.1) | 3.4 (0.1) | 0.0 (−0.2 to 0.2) | 0.13 | 0.65 |
| SF-36 (all/100) | ||||||
| Mental health | 75 (3) | 80 (2)* | 77 (2) | −3 (−10 to 3) | −0.22 | 0.74 |
| Bodily pain | 73 (4) | 75 (4) | 68 (4) | −7 (−17 to 3) | −0.31 | 0.04 |
| Social functioning | 79 (4) | 85 (5) | 78 (5) | −8 (−21 to 6) | −0.36 | 0.26 |
| Vitality | 44 (3) | 53 (3)** | 53 (3)** | −1 (−10 to 9) | −0.04 | 0.12 |
| Role emotional | 78 (7) | 89 (7) | 77 (7) | −12 (−32 to 9) | −0.30 | 0.82 |
| Role physical | 63 (8) | 82 (7)** | 66 (7) | −16 (−35 to 3) | −0.38 | 0.85 |
| Physical functioning | 82 (3) | 80 (2) | 81 (2) | 1 (−3 to 6) | 0.09 | 0.02 |
| General health | 74 (3) | 76 (2) | 76 (2) | 0 (−6 to 7) | 0.03 | 0.46 |
| HADS-Anxiety (21) | 6.8 (0.7) | 5.7 (0.4)** | 6.5 (0.4) | −0.8 (−1.9 to 0.4) | −0.20 | 0.52 |
| HADS-Depression (21) | 4.2 (0.5) | 3.5 (0.3)* | 3.8 (0.3) | −0.3 (−1.2 to 0.6) | −0.10 | 0.29 |
| Psychomotor vigilance task | ||||||
| Mean RT (ms) | 264 (5) | 259 (5) | 266 (5) | −7 (−20 to 7) | −0.15 | 0.16 |
| Lapses (>500 ms RT) | 1.3 (0.3) | 1.0 (0.4) | 1.3 (0.4) | −0.4 (−1.4 to 0.7) | −0.18 | 0.15 |
| Errors | 2.8 (0.5) | 3.3 (0.7) | 3.2 (0.7) | 0.1 (−1.9 to 2.0) | 0.02 | 0.27 |