Table 3.
Hazard ratios (95% CI) for anemia according to sleep duration in the Kailuan Study.
| Total | Sleep duration(hours) | ||||
|---|---|---|---|---|---|
| ≤5 | 6 | 7 | 8 | ≥9 | |
| Case(incidence per 1000 person years) | 204 (4.93) | 510 (4.94) | 431 (4.01) | 1490 (4.47) | 63 (6.08) |
| Model 1 | 1.22 (1.03–1.44) | 1.26 (1.10–1.43) | reference | 1.08 (0.97–1.20) | 1.45 (1.11–1.89) |
| Model 2 | 1.24 (1.04–1.46) | 1.26 (1.11–1.44) | reference | 1.03 (0.92–1.15) | 1.45 (1.11–1.88) |
| Model 3 | 1.23 (1.04–1.45) | 1.26 (1.11–1.44) | reference | 1.04 (0.092–1.16) | 1.42 (1.08–1.86) |
| Sensitivity analysis* | 1.20 (1.01–1.43) | 1.22 (1.07–1.39) | reference | 1.01 (0.90–1.13) | 1.36 (1.03–1.80) |
| Sensitivity analysis† | 1.18 (1.02–1.38) | 1.22 (1.10–1.36) | 0.97 (0.86–1.08) | reference | 1.37 (1.06–1.78) |
| Women § | |||||
| Case(incidence per 1000 person years) | 41 (5.34) | 114 (6.73) | 116(5.40) | 622 (7.83) | 35 (14.03) |
| Model 1 | 1.20 (0.84–1.72) | 1.37 (1.06–1.78) | reference | 1.34 (1.10–1.63) | 2.22 (1.52–3.25) |
| Model 2 | 1.24 (0.86–1.77) | 1.39 (1.08–1.80) | reference | 1.26 (1.03–1.55) | 2.20 (1.50–3.21) |
| Model 3 | 1.20 (0.84–1.73) | 1.33 (1.02–1.74) | reference | 1.25 (1.02–1.54) | 2.29 (1.56–3.37) |
| Sensitivity analysis* | 1.14 (0.78–1.68) | 1.34 (1.02–1.76) | reference | 1.26 (1.02–1.55) | 2.37 (1.61–3.48) |
| Men § | |||||
| Case(incidence per 1000 person years) | 163 (4.84) | 396 (4.59) | 315(3.66) | 868 (3.42) | 28 (3.56) |
| Model 1 | 1.23 (1.02–1.49) | 1.22 (1.05–1.41) | reference | 0.93 (0.82–1.06) | 0.95 (0.65–1.40) |
| Model 2 | 1.24 (1.02–1.50) | 1.22 (1.05–1.42) | reference | 0.89 (0.77–1.02) | 0.95 (0.65–1.40) |
| Model 3 | 1.23 (1.02–1.49) | 1.23 (1.06–1.43) | reference | 0.90 (0.78–1.03) | 0.90 (0.60–1.34) |
| Sensitivity analysis* | 1.21 (1.00–1.47) | 1.18 (1.01–1.37) | reference | 0.86 (0.75–1.00) | 0.79 (0.51–1.21) |
| P for interaction | 0.168 | 0.777 | <0.001 | <0.001 | |
Model 1: Adjusted for age and sex.
Model 2: Adjusted for age, sex, level of education, smoking, alcohol, physical activity, and snoring.
Model 3: Adjusted for variables in Model 2 plus hypertension, diabetes mellitus, dyslipidemia, body mass index,
and high-sensitivity C-reactive protein.
*Adjusted for Model 3 and further excluded individuals with myocardial infarction, stroke and cancer.
§Adjusted for above confounding factors without sex.
†Adjusted for Model 3 and used 8 hours/night as the reference group.