Table 2.

Body mass index and incidence of invasive breast cancer among postmenopausal women

		STAR Postmenopausal				P-1 Postmenopausal				STAR/P-1 Postmenopausal a
Form of Cox Regression Model	Body mass index	N	No. of Events	HR	95% CI	N	No. of Events	HR	95% CI	N	No. of Events	HR	95% CI
Univariable assessment	< 25.0	5870	159	1.00		2204	42	1.00		7883	194	1.00
	25.0–29.9	6703	191	1.06	0.86 – 1.30	2188	48	1.21	0.80 – 1.84	8641	228	1.08	0.89 – 1.30
	≥ 30.0	6915	207	1.14	0.93 – 1.40	1987	37	1.07	0.69 – 1.66	8633	231	1.11	0.92 – 1.34
	p-value (trend)			0.22				0.74				0.29
Full multivariable assessmentb	< 25.0	5829	159	1.00		2194	42	1.00		7833	194	1.00
	25.0–29.9	6658	190	1.03	0.83 – 1.27	2182	48	1.23	0.81 – 1.86	8591	227	1.06	0.87 – 1.28
	≥ 30.0	6870	206	1.13	0.92 – 1.40	1978	36	1.07	0.68 – 1.67	8581	229	1.12	0.92 – 1.36
	p-value (trend)			0.24				0.73				0.25
Final multivariable assessmentc	< 25.0	5870	159	1.00		2204	42	1.00		7883	194	1.00
	25.0–29.9	6703	191	1.04	0.85 – 1.29	2188	48	1.22	0.81 – 1.85	8641	228	1.07	0.88 – 1.30
	≥ 30.0	6915	207	1.16	0.94 – 1.42	1987	37	1.09	0.70 – 1.69	8633	231	1.14	0.94 – 1.38
	p-value (trend)			0.16				0.68				0.17

Abbreviations: STAR-Study of Tamoxifen and Raloxifene, P-1-Breast Cancer Prevention Trial, HR-hazard ratio, CI-confidence interval.

^aFor participants in both P-1 and STAR, only their P-1 data were included.

^bAdjusted for treatment, Gail score, age, history of diabetes, history of oral contraceptive use, history of estrogen use, and years of cigarette smoking; STAR/P-1 combined also adjusted for trial. Those with unknown smoking status were excluded from analyses.

^cAdjusted for treatment, Gail score and age in STAR and STAR/P-1 combined; and treatment and Gail score in P-1.