TABLE 3.
SUMMARY OF MULTIPLE LINEAR REGRESSION MODEL RESULTS
| Epworth Sleepiness Scale
|
Multiple Sleep Latency Test
|
Performance Lapses†
|
DADT Tracking Error†
|
|||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Variable | Slope | SE | p Value | Slope | SE | p Value | Slope | SE | p Value | Slope | SE | p Value |
| Continuous risk factor model | ||||||||||||
| Apnea–hypopnea index (SD = 11.5/h) | 0.01 | 0.27 | 0.96 | −0.54 | 0.27 | 0.05 | 0.03 | 0.04 | 0.45 | 0.06 | 0.03 | 0.08 |
| Sleep duration (SD = 1.34 h) | −0.72 | 0.28 | 0.01 | 0.75 | 0.28 | 0.008 | −0.18 | 0.04 | 0.0001 | −0.11 | 0.03 | 0.0001 |
| Categorical risk factor model | ||||||||||||
| Apnea–hypopnea index category* | 0.81 | 0.07 | 0.007 | 0.10 | ||||||||
| > 30 vs. < 5 | 0.39 | 1.19 | 0.74 | −2.46 | 1.15 | 0.03 | 0.22 | 0.16 | 0.18 | 0.27 | 0.13 | 0.04 |
| 15–30 vs. < 5 | 0.46 | 0.94 | 0.62 | −0.88 | 0.96 | 0.36 | −0.07 | 0.14 | 0.64 | 0.09 | 0.10 | 0.38 |
| 5 to < 15 vs. < 5 | −0.40 | 0.66 | 0.54 | 0.58 | 0.66 | 0.38 | −0.26 | 0.09 | 0.005 | −0.05 | 0.07 | 0.46 |
| Sleep duration category* | 0.05 | 0.04 | 0.005 | 0.05 | ||||||||
| < 5 vs. 7–8 h | 2.05 | 0.85 | 0.02 | −2.29 | 0.85 | 0.007 | 0.39 | 0.12 | 0.001 | 0.26 | 0.09 | 0.003 |
| 5 to < 6 vs. 7–8 h | 1.95 | 0.74 | 0.009 | −0.66 | 0.74 | 0.38 | 0.18 | 0.10 | 0.08 | 0.10 | 0.08 | 0.20 |
| 6 to < 7 vs. 7–8 h | 0.65 | 0.66 | 0.33 | −0.80 | 0.67 | 0.23 | 0.11 | 0.09 | 0.23 | 0.10 | 0.07 | 0.13 |
| > 8 vs. 7–8 h | 0.72 | 1.21 | 0.55 | 1.31 | 1.25 | 0.29 | −0.23 | 0.17 | 0.18 | −0.02 | 0.12 | 0.88 |
Definition of abbreviations: DADT = Divided Attention Driving Task; SE = standard error of the associated estimate.
Note: Slope refers to estimated model parameters. Slopes or sets of slopes as indicated (p < 0.05) are set boldface to highlight patterns of statistical significance. All multiple linear regression models included age, sex, and body mass index as well as either categorical factors for apnea–hypopnea index (AHI) category and sleep duration category or continuous variables for AHI and sleep duration. Sleep duration was estimated as the mean cumulative duration of relative inactivity as determined by actigraphy over 1 wk. Continuous variables were divided by estimated population standard deviation values so that linear slopes reflected the expected effects of a 1-SD increase. The SD values used were 11.5 for AHI and 1.34 for mean sleep duration as determined by actigraphy over 1 wk at home as the cumulative duration of relative inactivity.
p Value is for the overall categorical factor (degrees of freedom = 3 for apnea severity category and degrees of freedom = 4 for sleep duration category).
Psychomotor vigilance lapses (performance lapses) and DADT mean tracking error were transformed according to the function loge(x + 1) before analysis.