Table 2.

Odds ratios (95% confidence interval) of risk factors for breast cancer derived from univariate analysis entered into multivariate analysis

Risk factor	Odds ratio (95% CI)	P value
Age (years) v 40-49 years:
50-59	1.79 (0.91 to 3.53)	0.000*
60-69	10.68 (5.12 to 22.30)	0.000*
70-79	16.40 (7.26 to 37.03)	0.000*
History of benign breast lumps	0.19 (0.10 to 0.35)	0.000*
Months breast feeding v no breast feeding:
0.5-8	1.56 (0.88 to 2.77)	0.124*
>8	1.28 (0.74 to 2.22)	0.384
Menopausal status v premenopausal:
Perimenopausal	0.99 (0.39 to 2.48)	0.977
Postmenopausal	3.34 (1.76 to 6.35)	0.000*
Age at menopause v premenopausal:
28-40	1.54 (0.59 to 3.99)	0.377
41-49	2.81 (1.47 to 5.37)	0.002*
>50	5.82 (2.85 to 11.85)	0.000*
Age at hysterectomy v no hysterectomy:
27-42	0.39 (0.16 to 0.98)	0.045*
>43	1.72 (0.87 to 3.37)	0.117*
Ever had hormone replacement therapy	0.71 (0.43 to 1.19)	0.194*
Years of hormone replacement therapy v never had hormone replacement therapy:
0.2-4.5	0.64 (0.32 to 1.27)	0.203*
5.0-24.0	0.79 (0.41 to 1.50)	0.470
Past use of oral contraceptive pill	0.39 (0.24 to 0.62)	0.000*
No of years taking oral contraceptive pill v never taken oral contraceptive pill:
0.25-6.5	0.35 (0.19 to 0.62)	0.000*
7.0-22.0	0.44 (0.24 to 0.79)	0.007*
Body mass index (kg/m2) v 17.0-22.0 kg/m2:
22.1-24.2	0.67 (0.50 to 0.97)	0.008*
24.3-47.0	1.46 (1.08 to 1.97)	0.013*
Units of alcohol/week v 0 units/week:
1-4	0.57 (0.31 to 1.04)	0.068*
5-9	0.60 (0.31 to 1.15)	0.124*
⩾10	0.78 (0.40 to 1.49)	0.448

^*P<0.25; variable entered into multivariate analysis.