Table 1.
Baseline characteristics of 13,331 participants of NHANES III by 25(OH)D quartiles. Results presented as means or percents ± standard error.
| 25-hydroxyvitamin D levels (ng/ml)* | |||||
|---|---|---|---|---|---|
| >32.1 | 24.4-32.1 | 17.8-24.4 | <17.8 | P-value | |
| Characteristic | (n=3359) | (n=3242) | (n=3344) | (n=3386) | |
| Age (years) | 41.9 ± 0.5 | 45.2 ± 0.6 | 46.7 ± 0.6 | 45.5 ± 0.6 | <0.001 |
| Women (%) | 45.0 ± 1.2 | 50.5 ± 1.0 | 56.1 ± 1.4 | 66.3 ± 1.4 | <0.001 |
| Race (%) | |||||
| Non-Hispanic white | 91.4 ± 0.9 | 82.6 ± 1.2 | 69.3 ± 1.8 | 48.1 ± 2.5 | <0.001 |
| Non-Hispanic black | 2.1 ± 0.3 | 5.4 ± 0.5 | 13.3 ± 0.9 | 32.8 ± 1.9 | <0.001 |
| Mexican-American | 2.6 ± 0.3 | 4.8 ± 0.5 | 6.7 ± 0.6 | 7.2 ± 0.7 | <0.001 |
| Other | 3.9 ± 0.9 | 7.1 ± 0.9 | 10.7 ± 1.3 | 11.8 ± 1.3 | <0.001 |
| Diabetic (%) | 3.8 ± 0.5 | 6.6 ± 0.5 | 8.2 ± 0.8 | 10.9 ± 0.8 | <0.001 |
| History of CVD (%) | 6.0 ± 0.5 | 7.9 ± 0.8 | 9.5 ± 0.9 | 8.2 ± 0.9 | 0.002 |
| Hypertension (%) | 19.3 ± 1.1 | 23.8 ± 1.2 | 27.8 ± 1.2 | 28.9 ± 1.3 | <0.001 |
| BMI (kg/m2) | 25.3 ± 0.1 | 26.4 ± 0.2 | 27.6 ± 0.2 | 28.1 ± 0.2 | <0.001 |
| Total cholesterol (mg/dl) | 202.2 ± 1.0 | 202.8 ± 1.3 | 207.5 ± 1.3 | 203.5 ± 1.2 | 0.04 |
| HDL cholesterol (mg/dl) | 51.2 ± 0.5 | 49.8 ± 0.5 | 50.4 ± 0.5 | 51.8 ± 0.4 | 0.73 |
| Cholesterol medication use (%) |
2.4 ± 0.3 | 2.7 ± 0.4 | 3.3 ± 0.4 | 3.7 ± 0.7 | 0.02 |
| Systolic BP (mm Hg) | 120.1 ± 0.6 | 122.3 ± 0.5 | 124.0 ± 0.5 | 124.4 ± 0.6 | <0.001 |
| Diastolic BP (mm Hg) | 73.6 ± 0.2 | 74.2 ± 0.3 | 74.7 ± 0.3 | 75.0 ± 0.3 | <0.001 |
| Smoking (%) | |||||
| Former | 28.3 ± 1.2 | 26.8 ± 1.1 | 25.3 ± 1.2 | 21.5 ± 1.3 | 0.001 |
| Current | 29.0 ± 1.4 | 26.0 ± 1.4 | 26.9 ± 1.3 | 32.6 ± 1.3 | 0.26 |
| Season (%) | |||||
| Winter (Jan.-March) | 10.6 ± 2.1 | 15.3 ± 2.3 | 20.6 ± 3.6 | 27.3 ± 4.7 | <0.001 |
| Spring (April-June) | 22.0 ± 4.1 | 28.8 ± 4.6 | 28.8 ± 4.3 | 26.3 ± 4.3 | 0.04 |
| Summer (July-Sept.) | 43.4 ± 5.5 | 33.1 ± 5.6 | 26.0 ± 4.2 | 19.2 ± 3.5 | <0.001 |
| Fall (Oct.-Dec.) | 24.0 ± 4.7 | 22.8 ± 4.5 | 24.7 ± 4.0 | 27.2 ± 4.1 | 0.34 |
| eGFR <60 ml/min/1.73m2 (%) |
3.3 ± 0.4 | 4.1 ± 0.4 | 4.8 ± 0.5 | 4.6 ± 0.6 | <0.001 |
| Albumin excretion ≥30 mg/g creatinine (%) |
6.1 ± 0.4 | 7.4 ± 0.7 | 9.9 ± 0.6 | 12.6 ± 1.1 | <0.001 |
| C-reactive protein >0.21 mg/dl (%) |
24.0 ± 1.5 | 26.6 ± 1.6 | 30.7 ± 1.6 | 37.0 ± 1.7 | <0.001 |
| Serum albumin (g/dl) | 4.23 ± 0.02 | 4.21 ± 0.03 | 4.14 ± 0.02 | 4.08 ± 0.02 | <0.001 |
| Low SES (%) | 29.8 ± 1.5 | 29.4 ± 1.4 | 35.7 ± 2.0 | 41.9 ± 1.6 | <0.001 |
| Vitamin D use (%) | 35.2 ± 1.3 | 30.1 ± 1.2 | 25.2 ± 1.2 | 16.3 ± 1.3 | <0.001 |
| Physical Activity | |||||
| Moderate (%) | 55.6 ± 1.3 | 56.4 ± 1.1 | 53.7 ± 2.0 | 48.1 ± 1.4 | 0.002 |
| High (%) | 28.7 ± 1.5 | 20.9 ± 1.0 | 16.6 ± 1.1 | 11.7 ± 1.3 | <0.001 |
*
To convert to SI units, multiply 25(OH)D value by 2.496.