Table 1.
Baseline characteristics of a case-control study nested within the CLUE II Cohort (1989–2005)
| Cases (n=272) | Controls (n=272) | p-value | |
|---|---|---|---|
| Age at blood-draw, years, mean (SD) | 62.6 (9.4) | 62.5 (9.2) | 0.9 |
| BMI* at baseline, kg/m2, mean (SD) | 27.1 (0.3) | 25.7 (0.3) | 0.002 |
| BMI category, n(%) | 0.001 | ||
| Normal (<25kg/m2) | 100 (36.8) | 143 (52.6) | |
| Overweight (25 – <30 kg/m2) | 102 (37.5) | 79 (29.0) | |
| Obese (>=30 kg/m2) | 70 (25.7) | 50 (18.4) | |
| Education, n(%) | 0.7 | ||
| <12 years | 84 (30.9) | 88 (32.4) | |
| 12 years | 106 (39.0) | 111 (40.8) | |
| >12 years | 82 (30.2) | 74 (26.8) | |
| Married at baseline, n (%) | 192 (70.6) | 176 (64.7) | 0.36 |
| Cigarette smoking, n (%) | 0.46 | ||
| Never | 166 (61.0) | 173 (63.6) | |
| Former | 73 (26.8) | 61 (22.4) | |
| Current | 33 (12.1) | 38 (14.0) | |
| Alcohol use, n (%) | 0.77 | ||
| Never | 206 (75.7) | 203 (74.6) | |
| Ever | 66 (24.3) | 69 (25.4) | |
| Gravidity, n (%) | |||
| Ever pregnant | 201 (73.9) | 194 (71.3) | 0.60 |
| Never pregnant | 27 (9.9) | 25 (9.2) | |
| Missing | 44 (16.2) | 53 (19.5) | |
| Age at first birth of those reporting pregnancy (n=395), n (%) | 0.33 | ||
| <20 years | 54 (26.9) | 45 (23.2) | |
| 20–24 years | 98 (48.8) | 92 (47.4) | |
| 25–29 years | 37 (18.4) | 34 (17.5) | |
| ≥30 years | 10 (5.0) | 20 (10.3) | |
| Missing | 2 (1.0) | 3 (1.6) | |
| Ever breastfed, n (%) | 72 (26.5) | 84 (30.9) | 0.33 |
| Age at menarche, n (%) | 0.40 | ||
| <12 years | 33 (12.1) | 40 (14.7) | |
| 12–13 years | 128 (47.1) | 109 (40.1) | |
| >13 years | 54 (19.9) | 63 (23.2) | |
| Missing | 57 (21.0) | 60 (22.1) | |
| Ever oral contraceptive use, n (%) | 39 (14.3) | 35 (12.9) | 0.54 |
| Hormone therapy use**, n (%) | 0.04 | ||
| Never | 204 (75.0) | 196 (72.1) | |
| Former | 31 (11.4) | 49 (18.0) | |
| Current | 35 (12.9) | 22 (8.1) | |
| Missing | 2 (0.7) | 5 (1.8) | |
| Family history of breast cancer***, n (%) | 0.003 | ||
| None | 169 (62.1) | 195 (71.7) | |
| Yes | 55 (20.2) | 27 (9.9) | |
| Missing | 48 (17.7) | 50 (18.4) | |
| sTNF-R2, ng/ml****, mean (SD) | 3.2 (1.2) | 2.8 (0.9) | 0.005 |
| Leptin, ng/ml, mean (SD) | 32.9 (36.1) | 27.4 (27.4) | 0.007 |
| Adiponectin, ng/ml, mean (SD) | 7990.0 (3830.8) | 8703.7 (4042.0) | 0.02 |
*
BMI, body mass index, weight in kilograms divided by height in meters squared.
**
Hormone therapy use defined as ever use of hormone therapies other than oral contraceptives, including estrogen, progesterone, or a combination.
***
Family history defined as breast cancer in first-degree relatives and maternal and paternal grandparents.
****
sTNF-R2, leptin and adiponectin measured in plasma.