Overall and chronic illness-stratified distributions of serum 25(OH)D level according to baseline covariates
| 25(OH)D level (nmol/L) | ||||||
| Total (n=6377) | Chronic illness (first definition)† | |||||
| No (n=5256) | Yes (n=856) | |||||
| Mean | SD | Mean | SD | Mean | SD | |
| Total | 47.3 | 17.8 | 47.8 | 18.0 | 45.2 | 16.6 |
| Age (years) | ||||||
| <65 | 47.5 | 18.0 | 47.6 | 18.1 | 45.5 | 16.9 |
| ≥65 | 46.8*** | 17.0 | 48.5*** | 17.4 | 45.1 | 16.5 |
| Sex | ||||||
| Female | 47.0 | 17.6 | 47.9 | 17.9 | 42.2 | 14.9 |
| Male | 47.7 | 18.0 | 47.6 | 18.0 | 48.4** | 17.7 |
| Season of blood draw | ||||||
| Spring | 44.2 | 16.9 | 44.5 | 17.1 | 47.2 | 15.2 |
| Summer | 53.7*** | 17.9 | 54.7*** | 17.9 | 50.1*** | 17.1 |
| Fall | 50.8*** | 17.6 | 51.8*** | 17.6 | 46.7*** | 16.3 |
| Winter | 43.0 | 17.1 | 42.9 | 17.1 | 43.0 | 17.2 |
| Body mass index (kg/m2) | ||||||
| Normal/underweight (<25.0) | 51.1 | 18.3 | 51.5 | 18.4 | 47.8 | 16.3 |
| Overweight (25.0–29.9) | 46.4*** | 17.1 | 46.4*** | 17.3 | 46.9 | 16.3 |
| Obese (≥30.0) | 41.0*** | 15.8 | 41.0*** | 15.7 | 40.7*** | 16.2 |
| Unknown | 37.2 | 16.0 | 37.8 | 16.2 | 36.6 | 16.7 |
| Daily smoker | ||||||
| Never | 48.0 | 17.9 | 48.5 | 18.2 | 44.5 | 15.7 |
| Former | 48.8 | 17.3 | 49.1 | 17.1 | 47.9 | 18.2 |
| Current | 45.1*** | 17.6 | 45.6*** | 17.9 | 42.4** | 15.0 |
| Unknown | 47.3 | 20.9 | 48.5 | 22.4 | 41.7 | 12.1 |
| Alcohol consumption (times per month) | ||||||
| Never | 45.1 | 16.4 | 45.6 | 16.6 | 43.5 | 15.7 |
| 1–4 | 48.3*** | 18.1 | 48.4*** | 18.2 | 47.1 | 16.0 |
| ≥5 | 51.1*** | 19.4 | 51.0*** | 19.0 | 52.3** | 23.0 |
| Unknown | 46.1 | 18.2 | 47.0 | 18.9 | 44.4 | 15.5 |
| Physical activity | ||||||
| Inactive or very low | 44.6 | 16.8 | 45.0 | 17.1 | 43.3 | 15.3 |
| Low | 47.7* | 17.7 | 47.4 | 17.6 | 50.5* | 18.7 |
| Moderate | 50.2*** | 17.8 | 50.3*** | 17.9 | 48.1 | 17.0 |
| High | 52.2*** | 20.9 | 52.7*** | 21.1 | 47.7 | 16.7 |
| Unknown | 45.7 | 16.9 | 45.3 | 17.1 | 43.9 | 16.3 |
| Education (years) | ||||||
| <10 | 45.6 | 16.8 | 46.3 | 17.1 | 43.7 | 15.9 |
| 10–12 | 47.6* | 18.3 | 47.4 | 18.2 | 48.6 | 18.4 |
| ≥13 | 50.0* | 18.3 | 50.1 | 18.5 | 48.1 | 16.3 |
| Unknown | 43.4 | 15.7 | 44.2 | 15.8 | 43.7 | 15.7 |
| Economic difficulties | ||||||
| No | 48.7 | 17.3 | 48.9 | 17.5 | 46.5 | 14.6 |
| Yes | 46.2** | 18.4 | 46.4** | 18.0 | 45.0 | 22.0 |
| Unknown | 45.8 | 17.9 | 46.6 | 18.7 | 44.6 | 16.3 |
Multiple linear regression analysis was used to compare the mean levels of 25(OH)D with the first category (reference) for each baseline covariate.
*p<0.05; **p<0.01; ***p<0.001.
†265 subjects with missing information on chronic illness (first definition) at baseline were excluded.
25(OH)D, 25-hydroxyvitamin D.