Table 3.
Estimated hazard ratio for potential predictors of the first episode of intermittent excessive daytime sleepiness (EDS) compared to persistent EDS, and of the first episode of transient daytime sleepiness (DS) decrease compared to those with a stable condition
| Variable | Persistent EDS N = 233EDS | Intermittent N = 314 | HR [95% CI]* | P-Value | No ESS change N = 1330 | Transient DS improvement N = 184 | HR [95% CI]* | P-Value | ||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| n | % | n | % | n | % | n | % | |||||
| Baseline characteristics | ||||||||||||
| Gender, women | 138 | 59.23 | 202 | 64.33 | 1.07 [0.84–1.36] | 0.59 | 849 | 63.83 | 118 | 64.13 | 1.00 [0.74–1.35] | 0.99 |
| Educational level | ||||||||||||
| Secondary level | 76 | 32.62 | 80 | 25.48 | 1 | 0.59 | 387 | 29.10 | 61 | 33.15 | 1 | 0.12 |
| Degree below bachelor | 82 | 35.19 | 120 | 38.22 | 1.17 [0.87–1.57] | 478 | 35.94 | 67 | 36.41 | 0.81 [0.57–1.16] | ||
| Bachelor or above | 75 | 32.19 | 114 | 36.31 | 1.12 [0.83–1.51] | 465 | 34.96 | 56 | 30.43 | 0.68 [0.47–0.98] | ||
| Living alone, Yes (vs. No) | 79 | 33.91 | 124 | 39.49 | 1.19 [0.94–1.50] | 0.14 | 514 | 38.65 | 76 | 41.30 | 1.19 [0.88–1.60] | 0.27 |
| Smoking status | ||||||||||||
| Not a smoker | 181 | 78.02 | 253 | 80.57 | 1 | 0.91 | 1055 | 79.38 | 137 | 74.46 | 1 | 0.05 |
| Current smoker | 37 | 15.95 | 46 | 14.65 | 0.95 [0.69–1.31] | 199 | 14.97 | 38 | 20.65 | 1.54 [1.07–2.22] | ||
| Occasional smoker | 14 | 6.03 | 15 | 4.78 | 0.92 [0.54–1.56] | 75 | 5.64 | 9 | 4.89 | 0.86 [0.43–1.69] | ||
| Coffee consumption | ||||||||||||
| No | 41 | 17.67 | 52 | 16.56 | 1 | 0.54 | 221 | 16.63 | 37 | 20.22 | 1 | 0.39 |
| One–two cups per day | 103 | 44.40 | 146 | 46.50 | 1.20 [0.86–1.65] | 637 | 47.93 | 76 | 41.53 | 0.82 [0.55–1.23] | ||
| Three or more cups per day | 88 | 37.93 | 116 | 36.94 | 1.18 [0.84–1.67] | 471 | 35.44 | 70 | 38.25 | 1.01 [0.66–1.53] | ||
| Alcohol consumption | ||||||||||||
| No | 176 | 77.19 | 234 | 74.76 | 0.86 [0.59–1.23] | 0.36 | 999 | 75.74 | 140 | 76.92 | 1.00 [0.61–1.65] | 0.99 |
| One drink per day | 28 | 12.28 | 45 | 14.38 | 1.05 [0.67–1.66] | 179 | 13.57 | 24 | 13.19 | 0.97 [0.52–1.79] | ||
| Two or more drinks per day | 24 | 10.53 | 34 | 10.86 | 1 | 141 | 10.69 | 18 | 9.89 | 1 | ||
| Physical activity | ||||||||||||
| ≥4 times per week | 63 | 27.16 | 76 | 24.20 | 0.92 [0.66–1.27] | 0.78 | 393 | 29.68 | 45 | 24.46 | 0.70 [0.47–1.05] | 0.22 |
| [1–3] times per week | 107 | 46.12 | 163 | 51.91 | 1.01 [0.77–1.34] | 621 | 46.90 | 90 | 48.91 | 0.85 [0.60–1.20] | ||
| < 1 per week/never | 62 | 26.72 | 75 | 23.89 | 1 | 310 | 23.41 | 49 | 26.63 | 1 | ||
| Hypnotic intake, Yes (vs. No) | 29 | 12.61 | 20 | 6.49 | 0.58 [0.36–0.92] | 0.02 | 206 | 15.69 | 24 | 13.04 | 0.84 [0.55–1.30] | 0.44 |
| Time-dependent covariates 1-year before the first intermittent EDS/Transient DS improvement | ||||||||||||
| Sleep duration (h) | ||||||||||||
| ≥8 | 49 | 21.03 | 72 | 23.30 | 1.23 [0.83–1.81] | 0.37 | 412 | 31.07 | 40 | 21.98 | 0.48 [0.30–0.76] | 0.007 |
| [7–8] | 80 | 34.33 | 123 | 39.81 | 1.23 [0.86–1.75] | 482 | 36.35 | 59 | 32.42 | 0.57 [0.37–0.87] | ||
| [6–7] | 62 | 26.61 | 71 | 22.98 | 0.98 [0.67–1.44] | 281 | 21.19 | 47 | 25.82 | 0.77 [0.50–1.20] | ||
| <6 | 42 | 18.03 | 43 | 13.92 | 1 | 151 | 11.39 | 36 | 19.78 | 1 | ||
| Insomnia severity index | ||||||||||||
| <8 | 86 | 36.91 | 141 | 44.90 | 1.14 [0.85–1.54] | 0.03 | 781 | 58.77 | 69 | 37.50 | 0.33 [0.23–0.47] | <0.0001 |
| [8–14] | 100 | 42.92 | 110 | 35.03 | 0.81 [0.59–1.12] | 391 | 29.42 | 64 | 34.78 | 0.55 [0.38–0.80] | ||
| ≥15 | 47 | 20.17 | 63 | 20.06 | 1 | 157 | 11.81 | 51 | 27.72 | 1 | ||
| Beck Depression Inventory score | ||||||||||||
| ≤13 | 165 | 70.82 | 234 | 74.52 | 1.35 [0.94–1.94] | 0.26 | 1141 | 85.79 | 122 | 66.30 | 0.34 [0.23–0.51] | <0.0001 |
| [14–19] | 21 | 9.01 | 45 | 14.33 | 1.35 [0.86–2.13] | 100 | 7.52 | 28 | 15.22 | 0.74 [0.44–1.24] | ||
| [20–63] | 47 | 20.17 | 35 | 11.15 | 1 | 89 | 6.69 | 34 | 18.48 | 1 | ||
| Body mass index (kg/m2) | ||||||||||||
| <25 | 83 | 35.62 | 122 | 38.98 | 1.01 [0.76–1.33] | 0.85 | 567 | 42.63 | 80 | 43.48 | 0.78 [0.54–1.12] | 0.23 |
| [25–30] | 78 | 33.48 | 107 | 34.19 | 1.08 [0.80–1.44] | 503 | 37.82 | 58 | 31.52 | 0.72 [0.49–1.06] | ||
| ≥30 | 72 | 30.90 | 84 | 26.84 | 1 | 260 | 19.55 | 46 | 25.00 | 1 | ||
| Chronic pain, Yes (vs. No) | 87 | 37.34 | 88 | 28.03 | 0.85 [0.66–1.10] | 0.21 | 311 | 23.42 | 52 | 28.26 | 1.30 [0.94–1.80] | 0.11 |
| Cardiovascular disease, Yes (vs. No) | 26 | 11.21 | 23 | 7.37 | 1.09 [0.70–1.71] | 0.71 | 126 | 9.61 | 11 | 6.01 | 0.93 [0.50–1.73] | 0.81 |
| Hypertension, Yes (vs. No) | 58 | 25.66 | 59 | 19.22 | 0.87 [0.64–1.18] | 0.38 | 347 | 26.65 | 52 | 28.89 | 1.52 [1.07–2.16] | 0.02 |
| Endocrine and metabolic disease, Yes (vs. No) | 58 | 25.00 | 55 | 17.63 | 0.87 [0.65–1.18] | 0.38 | 317 | 24.07 | 43 | 23.50 | 1.37 [0.96–1.97] | 0.08 |
| Diabetes, Yes (vs. No) | 23 | 9.96 | 23 | 7.37 | 0.93 [0.60–1.44] | 0.75 | 128 | 9.76 | 19 | 10.38 | 1.47 [0.90–2.39] | 0.13 |
| Neurological disease, Yes (vs. No) | 48 | 20.87 | 44 | 14.10 | 0.83 [0.60–1.16] | 0.28 | 183 | 13.96 | 33 | 18.03 | 1.54 [1.06–2.26] | 0.02 |
| Other diseases, Yes (vs. No) | 140 | 60.09 | 143 | 45.69 | 0.78 [0.62–0.98] | 0.04 | 619 | 46.61 | 92 | 50.00 | 1.28 [0.95–1.73] | 0.11 |
| Changes observed at the time of the first intermittent EDS/transient DS improvement | ||||||||||||
| Change in sleep duration | ||||||||||||
| % of decrease (−7.21%)† | 53 | 24.20 | 59 | 20.27 | 0.81 [0.59–1.11] | 0.38 | 307 | 23.36 | 41 | 23.16 | 1.19 [0.80–1.77] | <0.0001 |
| No change | 104 | 47.49 | 153 | 52.58 | 1 | 723 | 55.02 | 66 | 37.29 | 1 | ||
| % of increase (+9.09%)† | 62 | 28.31 | 79 | 27.15 | 0.99 [0.74–1.33] | 284 | 21.61 | 70 | 39.55 | 2.28 [1.62–3.20] | ||
| Change in insomnia severity index | ||||||||||||
| % of decrease (−27.27%)† | 5 | 2.25 | 67 | 22.64 | 3.11 [2.26–4.27] | <0.0001 | 45 | 3.39 | 24 | 13.41 | 1.20 [0.76–1.90] | 0.02 |
| No change | 190 | 85.59 | 176 | 59.46 | 1 | 1089 | 82.13 | 141 | 78.77 | 1 | ||
| % of increase (+33.33%)† | 27 | 12.16 | 53 | 17.91 | 1.61 [1.16–2.24] | 192 | 14.48 | 14 | 7.82 | 0.46 [0.26–0.82] | ||
| Change in Beck Depression Inventory score | ||||||||||||
| % of decrease (−33.33%)† | 44 | 19.73 | 91 | 30.64 | 1.29 [0.97–1.73] | 0.21 | 309 | 23.27 | 75 | 41.44 | 1.73 [1.24–2.43] | 0.002 |
| No change | 129 | 57.85 | 139 | 46.80 | 1 | 661 | 49.77 | 71 | 39.23 | 1 | ||
| % of increase (+42.86%)† | 50 | 22.42 | 67 | 22.56 | 1.06 [0.77–1.44] | 358 | 26.96 | 35 | 19.34 | 1.02 [0.68–1.52] | ||
| Change in body mass index | ||||||||||||
| % of decrease (−2.44%)† | 57 | 25.68 | 71 | 24.07 | 1.04 [0.77–1.41] | 0.97 | 299 | 22.62 | 50 | 27.93 | 1.28 [0.90–1.81] | 0.09 |
| % of no change | 117 | 52.70 | 143 | 48.47 | 1 | 721 | 54.54 | 96 | 53.63 | 1 | ||
| % of increase (+3.23%)† | 48 | 21.62 | 81 | 27.46 | 1.01 [0.75–1.36] | 302 | 22.84 | 33 | 18.44 | 0.78 [0.52–1.16] | ||
| Change in chronic pain status | ||||||||||||
| Decrease | 25 | 11.21 | 26 | 8.78 | 0.76 [0.50–1.16] | 0.09 | 99 | 7.47 | 14 | 7.82 | 0.76 [0.43–1.35] | 0.59 |
| No change | 173 | 77.58 | 247 | 83.45 | 1 | 1114 | 84.08 | 148 | 82.68 | 1 | ||
| Increase | 25 | 11.21 | 23 | 7.77 | 0.64 [0.40–1.01] | 112 | 8.45 | 17 | 9.50 | 1.09 [0.65–1.83] | ||
DS, daytime sleepiness; EDS, Excessive Daytime Sleepiness; ESS: Epworth Severity Scale.
*Adjusted for age.
†For a given variable, the numbers in brackets correspond to the lowest (for decrease) or the highest quartile (for increase) of all relative differences between two consecutives evaluations.