Table 1.
Descriptive statistics for case and control subjects, and for case-control paired differences.
| Mean (SD) | Case - Sister control | Case - Unrelated control | |||||
|---|---|---|---|---|---|---|---|
| Case N = 228 |
Control | Mean (SD) N = 228 |
P valuec | Mean (SD) N = 228. |
P valuec | ||
| Sister N = 228 |
Unrelated N = 228 |
||||||
| Age at mammogram (years) | 50.7 (8.0) | 51.4 (8.1) | 50.9 (7.6) | - 0.68 (2.0) | <.0001 | -0.21 (0.8) | 0.0003 |
| Weight (kg) | 68.9 (13.7) | 68.8a (16.2) | 67.0 (15.9) | 0.15 (17.0)a | 0.89 | 1.88 (20.1) | 0.16 |
| Height (cm) | 163.3 (6.9) | 163.4b (6.2) | 162.5 (6.8) | - 0.02 (6.8)b | 0.96 | 0.81 (9.8) | 0.22 |
| Body mass index (kg/m2) | 25.8 (4.7) | 25.8b(5.8) | 25.3 (5.4) | 0.07 (6.0)b | 0.87 | 0.48 (7.0) | 0.30 |
| Menopausal status (% post) | 44.7 | 45.2 | 44.7 | -0.5 | 0.89 | 0 | 1.00 |
| Parous (% yes) | 79.8 | 84.2 | 80.7 | -4.4 | 0.19 | -0.9 | 0.81 |
| HRT ever used (% yes) | 41.7 | 34.4a | 37.3 | 7.3 | 0.08c | 4.4 | 0.30 |
| HRT current use (% yes) | 29.8 | 22.4 | 29.8 | 7.4 | 0.04 | 0 | 1.00 |
| Ethnicity (% white) | 92.1 | 92.1 | 93.0 | NA | NA | -0.9 | 0.72 |
| Family history (% yes) | 48 | 100 | 23 | NA | NA | NA | NA |
aN = 227; bN = 226. For analysis, the overall averages were substituted for the missing values; cpaired t-test for continuous variables and McNemar's test for categorical variables. HRT, hormone replacement therapy; SD, standard deviation.