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Table 1 Descriptive statistics for case and control subjects, and for case-control paired differences.

From: Mammographic density and breast cancer: a comparison of related and unrelated controls in the Breast Cancer Family Registry

  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
  1. 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.