Table 2.
Mean and Standard Deviation Values for Characteristics of Key Variables by Quartile of 25-Hydroxyvitamin D Level, Nurses’ Health Study, 1989–1990
| Variable | Quartile of 25-Hydroxyvitamin D Level |
||||
|---|---|---|---|---|---|
| 1 (n = 379) | 2 (n = 384) | 3 (n = 334) | 4 (n = 327) | P for Trenda | |
| Age, years | 58.6 (6.6) | 59.4 (6.3) | 59.7 (6.3) | 60.1 (6.0) | <.0001 |
| Smoking, pack-years | 13.1 (18.6) | 13.2 (19.6) | 11.1 (17.7) | 11.4 (18.0) | 0.04 |
| Body mass indexb | 27.6 (6.1) | 25.7 (4.9) | 25.2 (4.4) | 24.3 (4.0) | <0.0001 |
| Physical activity level, MET/week | 15.7 (35.3) | 17.1 (31.6) | 16.1 (16.3) | 20.3 (20.7) | 0.05 |
| Total calcium intake, mg/day | 1016.7 (505.6) | 1172.0 (619.9) | 1147.5 (525.9) | 1280.4 (601.8) | <0.0001 |
| Total folate intake, μg/day | 424.3 (225.0) | 478.2 (258.7) | 482.9 (234.4) | 515.6 (258.1) | <0.0001 |
| Total retinol intake, IU/day | 3392.6 (3494.7) | 4112.6 (4045.7) | 4137.3 (4849.3) | 4954.6 (5168.9) | <0.0001 |
Abbreviation: MET/week, metabolic equivalents per week.
a Age-adjusted linear regression P value for other variables.
b Weight (kg)/height (m)2.