Table 3.
Performance of VSW overnight sleep measures against PSG reference.
| Measure | Mean | Assumptions | Proport. bias | Lower LOA | Upper LOA | |||||
|---|---|---|---|---|---|---|---|---|---|---|
| PSG (SD) | VSW (SD) | Bias (95% CI) | Estimate | 95% CI | Estimate | 95% CI | Estimate | 95% CI | ||
| TST (min) | 384.98 (60.85) | 398.98 (49.04) | 14.00 (5.55, 23.20) | Prop Bias = T Normality = F Heteroscedastic = F | 125.51 + −0.29 x PSG | Intercept = [65.50, 186.28] Slope = [−0.45, −0.14] | −9.04 | [−87.36, 18.83] | 105.04 | [26.76, 133.36] |
| WASO (min) | 62.72 (49.97) | 49.60 (38.73) | −13.12 (−21.33, −6.21) | Prop Bias = T Normality = F Heteroscedastic = F | 7.11 + −0.32 × PSG | Intercept = [−3.68, 15.8] Slope = [−0.51, −0.10] | Bias - 2.46 (1.32 + 0.18 × PSG) | Intercept = [−2.91, 6.58] Slope = [0.06, 0.27] | Bias + 2.46 (1.32 + 0.18 × PSG) | Intercept = [−2.91, 6.58], Slope = [0.06, 0.27] |
| SE (%) | 81.69 (11.71) | 84.67 (9.01) | 2.97 (1.25, 4.84) | Prop Bias = T Normality = F Heteroscedastic = T | 30.04 + −0.33 × PSG | Intercept = [14.81, 42.28] Slope = [−0.47, −0.16] | Bias - 2.46 (11.98 + −0.11 x PSG) | Intercept = [4.19, 21.56], Slope = [−0.22, −0.02] | Bias + 2.46 (11.98 + −0.11 × PSG) | Intercept = [4.19, 21.56], Slope = [−0.22, −0.02] |
| SOL (min) | 25.43 (20.37) | 24.09 (19.73) | −1.34 (−7.29, 4.81) | Prop Bias = T Normality = F Heteroscedastic = F | 11.7 + −0.51 × PSG | Intercept = [3.28, 21.81] Slope = [−0.86, −0.15] | −44.21 | [−84.21, −7.38] | 34.21 | [−5.59, 70.51] |
| Light (min) | 240.65 (49.27) | 242.56 (43.83) | 1.91 (−8.28, 11.98) | Prop Bias = T Normality = T Heteroscedastic = F | 83.34 + −0.34 × PSG | Intercept = [40.42, 123.65] Slope = [−0.51, −0.17] | −25.06 | [−119.66, −10.10] | 107.06 | [12.69, 122.06] |
| Deep (min) | 63.39 (27.19) | 68.62 (20.12) | 5.24 (−3.35, 14.13) | Prop Bias = T Normality = T Heteroscedastic = F | 54.33 + −0.77 × PSG | Intercept = [40.81, 67.44] Slope = [−0.95, −0.60] | −72.30 | [−97.21, 3.10] | 39.31 | [14.51, 114.76] |
| REM (min) | 82.49 (25.46) | 88.88 (23.60) | 6.39 (−0.68, 13.18) | Prop Bias = T Normality = T Heteroscedastic = F | 45.69 + −0.48 × PSG | Intercept = [26.79, 69.87] Slope = [−0.78, −0.24] | −21.48 | [−84.16, −3.21] | 68.48 | [5.91, 86.55] |
| Measure | PSG mean (SD) | VSW mean (SD) | Mean difference (95% CI) | PSG median | VSW median | Median difference (95% CI) | Linear weighted kappa (95% CI) | |||
| NAWK (count) | 2.17 (1.96) | 1.88 (2.31) | 0.05 (−0.42, 0.53) | 1 | 1 | 0.0 (0.0, 0.0) | 0.58 (0.41, 0.71) | |||
CI, confidence interval; LOA, Limits of Agreement; NAWK, Night Awakenings; PPV, Positive Predictive Value; PSG, Polysomnography; REM, Rapid Eye Movement; SD, Standard Deviation; SE, Sleep Efficiency; SOL, Sleep Onset Latency; TST, Total Sleep Time; VSW, Verily Study Watch; WASO, Wake After Sleep Onset.