TABLE 1.
Baseline characteristics of CHD cases and controls in the Nurses' Health Study1
| Characteristics2 | Cases | Controls | P-value3 |
|---|---|---|---|
| n | 242 | 483 | |
| Demography and lifestyle | |||
| Age, y | 60.3 ± 6.5 | 60.3 ± 6.5 | 0.96 |
| BMI, kg/m2 | 26.8 ± 5.9 | 25.4 ± 4.4 | 0.001 |
| Physical activity, MET-h | 0.15 | ||
| Median | 10.3 | 11.9 | |
| Interquartile range | 4.6–21.5 | 5.8–21.8 | |
| Alcohol intake, g/d | 4.2 ± 9.4 | 6.1 ± 10.5 | 0.01 |
| Total iron intake, mg/d | 17.7 ± 12.2 | 18.0 ± 12.3 | 0.77 |
| Heme iron intake, mg/d | 1.1 ± 0.5 | 1.1 ± 0.6 | 0.49 |
| Red meat intake, g/d | 0.07 | ||
| Median | 52.2 | 46.2 | |
| Interquartile range | 32.0–86.9 | 29.2–76.0 | |
| Aspirin use, % | 62.8 | 65.8 | 0.42 |
| Smoking status, % | 0.95 | ||
| Current smoker | 31.4 | 31.7 | |
| Former smoker | 33.5 | 34.4 | |
| Never smoked | 35.1 | 34.0 | |
| Medical history, % | |||
| Diabetes | 20.3 | 6.6 | <0.0001 |
| Hypertension | 57.9 | 29.0 | <0.0001 |
| Hypercholesterolemia | 53.7 | 39.8 | 0.0004 |
| Parental MI before age 65 y | 30.2 | 16.6 | <0.0001 |
| Fasting status | 69.8 | 67.1 | 0.45 |
| Postmenopausal status | 0.18 | ||
| Premenopausal | 9.5 | 11.4 | |
| Current PMH user | 22.3 | 17.4 | |
| Past PMH user | 30.6 | 36.9 | |
| Never used PMH | 37.6 | 34.4 | |
| Biomarker4 | |||
| sTfR:ferritin ratio | 0.07 | 0.06 | 0.53 |
| Ferritin, μg/L | 105.4 ± 144.6 | 88.0 ± 77.8 | 0.08 |
| sTfR,5 mg/L | 2.20 ± 1.05 | 2.02 ± 0.92 | 0.02 |
| CRP,6mg/L | 5.67 ± 6.45 | 3.93 ± 4.94 | 0.0003 |
| ICAM-1,6μg/L | 291.2 ± 75.5 | 278.0 ± 105.0 | 0.05 |
| VCAM-1,6μg/L | 699.9 ± 169.5 | 670.4 ± 155.6 | 0.02 |
| E-selectin,6μg/L | 52.6 ± 25.0 | 46.6 ± 22.5 | 0.001 |
| IL-6,6ng/L | 2.8 ± 3.4 | 2.4 ± 3.1 | 0.12 |
Values are means ± SD or % unless indicated. Percentages are based on nonmissing data.
MET-h, metabolic equivalent-hours; MI, myocardial infarction; PMH, postmenopausal hormone use.
P-value estimates are based on Student's t test for variables expressed as 
± SD, Wilcoxon's rank-sum test for variables expressed as medians or Pearson χ2 test for variables expressed as percentages.
All Biomarkers were measured in plasma.
Concentrations were 1.67 ± 0.49 and 1.54 ± 0.48 for cases and controls selected in 1990–1996, respectively (P = 0.007) and 3.26 ± 1.05 and 2.98 ± 0.86 for cases and controls selected in 1997–1998, respectively (P = 0.03).
Controls, n = 473 for CRP, 477 for ICAM-1, 475 for VCAM-1, 477 for E-selectin, and 461 for IL-6; cases, n = 237 for CRP, 241 for ICAM-1, 240 for VCAM-1, 241 for E-selectin, and 230 for IL-6.