Table 1.
Characteristics of 538 subjects for the data analysis
| Characteristic | Total (n = 538) |
|---|---|
| Age at blood draw (yr) | 61.4 ± 8.0 |
| Gender [n (%)] | |
| Female | 326 (60.6) |
| Male | 212 (39.4) |
| Race [n (%)] | 209 (38.8) |
| White | 329 (61.2) |
| Black | 197 (36.6) |
| Other | 12 (2.2) |
| Height (cm) | 168.9 ± 8.8 |
| Weight (kg) | 82.8 ± 18.7 |
| BMI (kg/m2) | 28.9 ± 5.9 |
| Current smoker [n (%)] | |
| No | 462 (85.9) |
| Yes | 63 (11.7) |
| Unknown | 13 (2.4) |
| Season of first blood draw [n (%)] | |
| January–March | 316 (58.7) |
| April–June | 34 (6.3) |
| July–September | 99 (18.4) |
| October–December | 89 (16.5) |
| Months with shorter days (November–April) | 405 (75.3) |
| Months with longer days (May–October) | 133 (24.7) |
| Season of second blood draw [n (%)] | |
| January–March | 132 (24.5) |
| April–June | 19 (3.5) |
| July–September | 265 (49.3) |
| October–December | 122 (22.7) |
| Months with shorter days (November–April) | 185 (34.4) |
| Months with longer days (May–October) | 353 (65.6) |
| Latitude tertiles [n (%)] | |
| <35° | 144 (26.8) |
| 35–42° | 285 (53.0) |
| >42° | 109 (20.2) |
| Total daily supplements (IU) | |
| Missing [n (%)] | 94 (17.5) |
| 0 [n (%)] | 158 (29.4) |
| >0 [n (%)] | 286 (53.2) |
| Ambient UVR exposure | 96.7 ± 67.7 |
| First 25(OH)D measure (nmol/liter) | 67.6 ± 30.7 |
| Second 25(OH)D measure (nmol/liter) | 72.7 ± 32.2 |
| Time between 25(OH)D measures (months) | 8.4 ± 3.0 |
Results are shown as mean ± sd reported unless indicated otherwise.