Table 1.
Characteristics of the participants
| Factors | Cases N = 384 n(%) | Controls N = 566 n(%) | OR1 (95% CI) | OR2 (95% CI) |
| Age at interview | ||||
| ≤ 50 years | 138(36) | 178(31) | 1.00 | |
| >50 years | 246(64) | 388(69) | 0.82(0.62–1.08) | NS |
| Area of residence | ||||
| rural | 189(49) | 292(52) | 1.00 | |
| urban | 195(51) | 274(48) | 0.91(0.70–1.18) | NS |
| Menopausal status | ||||
| Pre/perimenopausal | 134(35) | 170(30) | 1.00 | |
| Postmenopausal | 250(65) | 396(70) | 0.80(0.60–1.06) | NS |
| Age at menopause3 | ||||
| ≤ 50 years | 144(59) | 252(64) | 1.00 | |
| >50 years | 102(41) | 140(36) | 1.28(0.92–1.77) | NS |
| Age of menarche | ||||
| ≤ 12 years | 155(40) | 150(27) | 1.86(1.41–2.45) | |
| >12 years | 229(60) | 412(73) | 1.00 | NS |
| Use of oral contraceptives | ||||
| no | 341(89) | 548(97) | 1.00 | 1.00 |
| yes | 43(11) | 18(3) | 3.84(2.18–6.77) | 4.40(1.46–13.28) |
| Use of HRT3 | ||||
| no | 231(92) | 393(99) | 1.00 | 1.00 |
| yes | 19(8) | 3(1) | 10.78(3.15–36.81) | 7.34(2.03–26.53) |
| First degree family history | ||||
| no | 341(89) | 522(92) | 1.00 | |
| yes | 43(11) | 44(8) | 1.5(0.96–2.33) | NS |
| Age at first full pregnancy | ||||
| <23 years | 106(35) | 239(50) | 1.00 | 1.00 |
| ≥ 23 years | 197(65) | 242(50) | 1.84(1.37–2.47) | 1.91(1.29–2.83) |
| Parity | ||||
| nulliparous | 79(20) | 78(14) | 1.00 | |
| 1–2 | 175(46) | 255(45) | 0.68(0.47–0.98) | NS |
| 3 plus | 130(34) | 233(41) | 0.55(0.38–0.80) | NS |
| Abortion or miscarriage | ||||
| no | 183(57) | 247(50) | 1.00 | 1.00 |
| yes | 138(43) | 248(50) | 0.75(0.57–0.99) | 0.56(0.38–0.82) |
| Lactation | ||||
| no | 67(22) | 84(17) | 1.00 | |
| yes | 238(78) | 404(82) | 0.74(0.52–1.06) | NS |
| Medication to suppress lactation | ||||
| no | 273(90) | 438(90) | 1.00 | |
| yes | 31(10) | 50(10) | 0.99(0.62–1.60) | NS |
| Radiation to the chest | ||||
| no | 372(97) | 550(97) | 1.00 | |
| yes | 12(3) | 16(3) | 1.11(0.52–2.37) | NS |
| Body mass index | ||||
| ≤ 29 kg/m2 | 282(74) | 498(88) | 1.00 | 1.00 |
| >29 kg/m2 | 97(26) | 68(12) | 2.52(1.79–3.55) | 3.13 (2.03–4.84) |
| Benign breast disease | ||||
| no | 315(82) | 472(83) | 1.00 | |
| yes | 69(18) | 94(17) | 1.10(0.78–1.55) | NS |
1Adjusted for age. -2Adjusted for age, residence, menopausal status, menopausal age, menarche age, use of OC, use of HRT, first degree family history, age at first full pregnancy, parity, abortion, lactation, medication to suppress lactation, radiation to the chest, body mass index and benign breast disease. -3Postmenopausal women only.
NS: non significant multivariate OR. Bold types: statistically significant values.