Table 4.

Cross-classification of weight change and hormone replacement therapy (HRT) use in postmenopausal women (n = 66 479)

Postmenopausal (n = 66 479/ca = 3409)c
Never HRT users (ca = 1369)					Ever HRT users (ca = 2040)d				Ever HRT userse
Weight change (kg)	Cases (n)	HRa	95% CI		Cases (n)	HR	95% CI		HR	95% CI
<–2.5	88	0.99	0.75	1.32	114	1.55	1.17	2.04	0.99	0.76	1.28
±2.5	134	1.00	Ref.		187	1.57	1.25	1.97	1.00	Ref.
2.51–5	104	1.07	0.83	1.38	192	1.82	1.45	2.27	1.16	0.94	1.42
5.1–10	256	1.01	0.81	1.25	481	1.85	1.52	2.26	1.18	0.99	1.41
10+	787	1.40	1.16	1.68	1066	1.92	1.60	2.32	1.23	1.04	1.44
P-intb									<0.0001

^aStratified by centre and age at recruitment (categorical 5-year interval) and adjusted for weight at age 20 years, height, age at menarche, number of pregnancies, age at first pregnancy, education, alcohol consumption, smoking status, physical activity, use of oral contraceptives and menopausal hormone therapy.

^b P-int = P for interaction using likelihood-ratio test comparing cross-classification model (weight change*HRT) with a model including HRT and weight change as separate variables.

^cOut of 71 751 postmenopausal women at cohort entry, there were 66 479 with information on HRT. Of all the 4891 postmenopausal breast-cancer cases, 3409 had information on HRT.

^dThis column has never HRT users and ±2.5 kg as reference group.

^eThis column has ever HRT users and ±2.5 kg as reference group.

95% CI, 95% confidence interval; HR, hazard ratio.