Table 1.
Vitamin D levels according to baseline characteristics (N = 1594)
| Variable | Total | Vitamin D level | χ2 / t | ||
|---|---|---|---|---|---|
| N(%) or M ( SD) | < 20 ng/mL (N = 1419) |
20 ng/mL ≤ (N = 175) | |||
| Sampling month | 12–2 | 575(36.1) | 537(37.8) | 38(21.7) | 17.599** |
| 3–5 | 235(14.7) | 203(14.3) | 32(18.3) | ||
| 6–8 | 571(35.8) | 495(34.9) | 76(43.4) | ||
| 9–11 | 213(13.4) | 184(13.0) | 29(16.6) | ||
| Age (years) | 33.15(6.32) | 32.89 ( 6.28) | 35.26 ( 6.24) | −4.716*** | |
| 20–29 | 593(37.2) | 558(39.3) | 35(20.0) | 25.486*** | |
| 30–39 | 697(43.7) | 603(42.5) | 94(53.7) | ||
| 40≤ | 304(19.1) | 258(18.2) | 46(26.3) | ||
| Marital status | Unmarried | 850(53.3) | 776(54.7) | 74(42.3) | 9.625** |
| Married or other | 744(46.7) | 643(45.3) | 101(57.7) | ||
| Education | Diploma | 312(19.6) | 290(20.4) | 22(12.6) | 8.228* |
| Bachelor | 1003(62.9) | 890(62.7) | 113(64.6) | ||
| Master’s or higher | 279(17.5) | 239(16.8) | 40(22.9) | ||
| Shift work | Yes | 1127(70.7) | 1019(71.8) | 108(61.7) | 7.667** |
| No | 467(29.3) | 400(28.2) | 67(38.3) | ||
| Overtime hours (week) | 5.26 ( 4.71) | 5.33 ( 4.76) | 4. 66(4.32) | 1.778 | |
*p < .05, **p < .01, ***p < .001.