Table 3.

Odds ratios (ORs) and corresponding 95% confidence intervals (CIs) for breast cancer risk associated with body size at age 18 years

	KARMA			LIBRO1			Combined
Body size	Number	Age-adjusted OR (95% CI)	Multivariable OR (95% CI)a	Number	Age-adjusted OR (95% CI)	Multivariable OR (95% CI)a	Number	Age-adjusted OR (95% CI)	Multivariable OR (95% CI)b
Breast cancer overall
Small	705	1.00 (Reference)	1.00 (Reference)	1482	1.00 (Reference)	1.00 (Reference)	2187	1.00 (Reference)	1.00 (Reference)
Medium	1407	0.97 (0.87–1.07)	0.95 (0.86–1.06)	2638	0.85 (0.79–0.91)	0.85 (0.79–0.91)	4045	0.89 (0.84–0.94)	0.88 (0.83–0.94)
Large	160	0.79 (0.66–0.96)	0.78 (0.64–0.94)	334	0.68 (0.59–0.78)	0.69 (0.60–0.79)	494	0.72 (0.65–0.80)	0.72 (0.64–0.80)
P trend		0.005	0.013		<0.001	<0.001		<0.001	<0.001
Premenopausal breast cancer
Small	214	1.00 (Reference)	1.00 (Reference)	284	1.00 (Reference)	1.00 (Reference)	498	1.00 (Reference)	1.00 (Reference)
Medium	466	1.06 (0.87–1.31)	1.03 (0.84–1.28)	545	0.82 (0.70–0.97)	0.80 (0.68–0.94)	1011	0.91 (0.80–1.03)	0.88 (0.78–1.00)
Large	52	0.70 (0.49–1.00)	0.66 (0.46–0.95)	84	0.66 (0.50–0.86)	0.62 (0.47–0.81)	136	0.67 (0.54–0.83)	0.63 (0.51–0.78)
P trend		0.190	0.043		<0.001	<0.001		<0.001	<0.001
Postmenopausal breast cancer
Small	491	1.00 (Reference)	1.00 (Reference)	1198	1.00 (Reference)	1.00 (Reference)	1689	1.00 (Reference)	1.00 (Reference)
Medium	941	0.94 (0.83–1.07)	0.93 (0.82–1.06)	2093	0.83 (0.76–0.91)	0.84 (0.77–0.91)	3034	0.87 (0.81–0.93)	0.87 (0.81–0.93)
Large	108	0.87 (0.69–1.09)	0.86 (0.68–1.09)	250	0.67 (0.57–0.78)	0.69 (0.59–0.81)	358	0.72 (0.63–0.82)	0.74 (0.64–0.84)
P trend		0.065	0.142		<0.001	<0.001		<0.001	<0.001

Number is the number of breast cancer cases

^aAdjusted for age, age at menarche, family history of breast cancer, number of children and ever use of hormone replacement therapy

^bAdjusted for study, age, age at menarche, family history of breast cancer, number of children and ever use of hormone replacement therapy