Table 4 Crude and adjusted odds ratios (OR) and 95% confidence intervals (95% CI) for postmenopausal breast cancer risk factors among parous women
From: Postmenopausal breast cancer in Iran; risk factors and their population attributable fractions
Variable | Events | Crude OR | Adjusted OR1 |
|---|---|---|---|
Case/control | (95%CI) | (95%CI) | |
Parity | |||
 Overall | 455/481 |  |  |
 1 – 3 | 130/76 | 1 | 1 |
 4 – 6 | 227/197 | 0.67 (0.47 – 0.94) | 0.74 (0.50 – 1.09) |
 7+ | 98/208 | 0.27 (0.19 – 0.39) | 0.30 (0.20 – 0.47) |
 P for trend |  | < 0.001 | < 0.001 |
Age at first childbirth | |||
 Overall | 454/481 |  |  |
 <15 | 41/56 | 0.87 (0.56 – 1.34) | 0.55 (0.28 – 1.10) |
 15 - 24 | 318/381 | 1 | 1 |
 ≥ 25 | 95/44 | 2.57 (1.75 – 3.79) | 1.24 (0.40 – 3.80) |
 P for trend |  | < 0.001 | 0.77 |
Breastfeeding (months) | |||
 Overall | 454/481 |  |  |
 Never | 21/20 | 0.63 (0.33 – 1.20) | 0.93 (0.29 – 1.86) |
 1 – 94 | 268/162 | 1 | 1 |
 95 – 162 | 131/149 | 0.53 (0.39 – 0.72) | 0.87 (0.27 – 2.78) |
 > 162 | 34/150 | 0.13 (0.08 – 0.21) | 0.32 (0.08 – 1.22) |
 P for trend |  | < 0.001 | 0.30 |
Breastfeeding per child | |||
 Overall | 454/479 |  |  |
 Never | 21/20 | 0.91 (0.47 – 1.78) | 0.98 (0.71 – 1.35) |
 < 12 months | 125/110 | 1 | 1 |
 ≥ 12 months | 308/349 | 0.77 (0.57 – 1.04) | 0.92 (0.45 – 1.88) |
 P for trend |  | 0.20 | 0.68 |
OCP usage (months) | |||
 Overall | 454/481 |  |  |
 Never | 178/236 | 1 | 1 |
 1 – 48 | 135/90 | 1.50 (1.15 – 1.95) | 1.99 (1.03 – 3.83) |
 49 – 116 | 73/73 | 1.98 (1.42 – 2.77) | 2.25 (1.12 – 4.49) |
 > 116 | 68/82 | 1.32 (0.90 – 1.93) | 1.40 (0.66 – 2.99) |
 P for trend |  | 0.36 | 0.10 |