Table 2.
Association of vitamin D deficiency with covariates; results of bivariate analysis.
| Variables | Prevalence of Vitamin D Deficiency | Unadjusted PR (95% CI) | p-Value |
|---|---|---|---|
| Socio-demographic characteristics | |||
| Age (years) | - | 1.00 (0.98–1.02) | 0.89 |
| Gender | |||
| Male | 32.5 | 1.00 | |
| Female | 34.0 | 1.05 (0.67–1.63) | 0.84 |
| Ethnicity a | |||
| Chinese | 21.9 | 1.00 | |
| Non-Chinese | 59.7 | 2.73 (1.90–3.93) | <0.001 |
| Marital status | |||
| Single b | 34.7 | 1.00 | |
| Married | 31.9 | 0.92 (0.62–1.37) | 0.68 |
| Education | |||
| Up to pre-college | 37.0 | 1.00 | |
| College or above | 25.6 | 0.69 (0.45–1.07) | 0.10 |
| Monthly income | |||
| <S$4000 | 37.6 | 1.00 | |
| ≥S$4000 | 23.6 | 0.63 (0.39–1.00) | 0.05 |
| Lifestyle habits | |||
| Smoking status | |||
| Non/ex-smoker | 32.4 | 1.00 | |
| Current smoker | 35.1 | 1.08 (0.67–1.77) | 0.74 |
| Alcohol drinking | |||
| Non-drinker | 35.8 | 1.00 | |
| Drinker c | 29.8 | 0.83 (0.56–1.23) | 0.36 |
| Total minutes of leisure-time physical activity | - | 0.94 (0.87–1.00) | 0.08 |
| Intake of vitamin D rich foods (servings/day) d | - | 0.84 (0.52–1.33) | 0.45 |
| Regular use of vitamin D or calcium supplements e | |||
| No | 34.7 | 1.00 | |
| Yes | 7.1 | 0.21 (0.03–1.38) | 0.10 |
| Clinical and biochemical characteristics | |||
| Body mass index (kg/m2) | - | 1.07 (1.04–1.10) | <0.001 |
| Systolic blood pressure (mmHg) | - | 1.01 (1.00–1.02) | 0.05 |
| Diastolic blood pressure (mmHg) | - | 1.00 (0.99–1.02) | 0.62 |
| Fasting plasma glucose (mmol/L) | - | 1.13 (1.07–1.18) | <0.001 |
| Total cholesterol (mmol/L) | - | 0.94 (0.78–1.14) | 0.54 |
| Work-related factors | |||
| Years employed in the current company | - | 0.93 (0.77–1.11) | 0.41 |
| Work location | |||
| Aboveground | 35.0 | 1.00 | |
| Underground | 29.0 | 0.83 (0.54–1.26) | 0.37 |
| Job type | |||
| Control room worker | 24.1 | 1.00 | |
| Office worker | 31.2 | 1.30 (0.75–2.25) | 0.36 |
| Workshop worker | 46.0 | 1.91 (1.09–3.35) | 0.024 |
| Work hours/day | - | 0.92 (0.79–1.08) | 0.31 |
| Night shifts per month | - | 1.02 (0.83–1.25) | 0.87 |
PR—prevalence ratio; CI—confidence interval. a Chinese includes a small number of mixed ethnicities (Filipino Chinese) and Filipinos. Non-Chinese includes Indians and Malays; b Includes never married, widowed, and divorced; c Includes those who drank alcohol less than once a month or at least once a month; d Includes milk and whole eggs; e Includes cod liver oil, fish oil, and other vitamin D containing supplements or calcium supplements.