Table 2.
Negative binomial regressions for predicting sleep difficulty after 2 years.
| Baseline variable | Model 1 |
Model 2 |
Model 3 |
Model 4 |
Model 5 |
||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| IRR | 95%CI | p | IRR | 95%CI | p | IRR | 95%CI | p | IRR | 95%CI | p | IRR | 95%CI | p | |
| Walking volume (MET-h/week)a | 0.015 | ||||||||||||||
| Low (≤4.5) | 1.61 | 1.16–2.22 | 0.004 | ||||||||||||
| Moderate (4.6–10.5) | 1.24 | 0.88–1.74 | 0.228 | ||||||||||||
| High (>10.5) | 1 | ||||||||||||||
| Walking components | |||||||||||||||
| Frequency (day/week) | 0.120 | 0.820 | |||||||||||||
| Low (≤3) | 1.34 | 1.01–1.80 | 0.045 | 1.10 | 0.81–1.51 | 0.540 | |||||||||
| Moderate (4–6) | 1.05 | 0.73–1.51 | 0.803 | 1.01 | 0.70–1.46 | 0.943 | |||||||||
| High (7) | 1 | 1 | |||||||||||||
| Duration (min) | 0.009 | 0.164 | |||||||||||||
| Low (≤20) | 1.64 | 1.18–2.28 | 0.003 | 1.40 | 0.98–2.00 | 0.067 | |||||||||
| Moderate (21–40) | 1.15 | 0.82–1.60 | 0.420 | 1.10 | 0.78–1.54 | 0.584 | |||||||||
| High (>40) | 1 | 1 | |||||||||||||
| Speed (MET) | 0.002 | 0.050 | |||||||||||||
| Low (≤2.5) | 1.92 | 1.18–3.14 | 0.009 | 1.68 | 1.01–2.80 | 0.045 | |||||||||
| Moderate (2.6–3.5) | 1.27 | 0.77–2.09 | 0.353 | 1.25 | 0.76–2.07 | 0.379 | |||||||||
| High (>3.5) | 1 | 1 | |||||||||||||
Notes: Covariates are (from Model 1 to Model 5) age (p = 0.486, 0.419, 0.484, 0.491, 0.515, respectively), sex (p = 0.529, 0.510, 0.525, 0.595, 0.548, respectively), years of schooling (p = 0.048, 0.018, 0.030, 0.030, 0.056, respectively), marital status (p = 0.851, 0.730, 0.836, 0.957, 0.891, respectively), living arrangement (p = 0.132, 0.142, 0.202, 0.179, 0.315, respectively), smoking (p = 0.063, 0.089, 0.082, 0.091, 0.076, respectively), alcohol drinking (p = 0.001, 0.002, 0.001, 0.008, 0.004, respectively), Charlson Index (all p < 0.001), mental health (p = 0.112, 0.127, 0.164, 0.063, 0.098, respectively), exercise (excluding walking) (p = 0.020, 0.022, 0.022, 0.019, 0.029, respectively), and sleep difficulty at baseline (all p < 0.001). p values for variables (walking volume, frequency, duration, and speed) are of comparison between baseline and follow-up; p values for levels (low and moderate) are of comparison with high level.
Abbreviations: CI = confidence interval; IRR = incident rate ratio; MET = metabolic equivalent value.
The total walking volume in MET-h/week = walking frequency × duration × speed.