. Author manuscript; available in PMC: 2009 Jun 30.

Published in final edited form as: Am J Epidemiol. 2008 Apr 29;167(12):1407–1415. doi: 10.1093/aje/kwn090

TABLE 2.

Breast cancer hazard ratio estimates for CEE^* according to prior postmenopausal hormone therapy status and years from hormone therapy initiation for US women, 1993–2004^†

No. of years from CEE initiation	Prior HT^*,^‡			No prior HT^‡
No. of years from CEE initiation	HR^*	95% CI^*	No. of cases^§	HR	95% CI	No. of cases^§
<2	1.24	0.57, 2.68	12/1	0.72	0.30, 1.70	8/2
2–5	0.72	0.42, 1.24	17/4	0.75	0.46, 1.21	23/12
>5	0.83	0.52, 1.35	17/41	0.71	0.45, 1.12	14/191

CEE, 0.625 mg/day of conjugated equine estrogens; HT, postmenopausal hormone therapy; HR, hazard ratio; CI, confidence interval.

^†

CEE in the observational study/CEE in the clinical trial: HR = 1.43, 95% CI: 0.91, 2.26.

^‡

Prior HT was defined relative to the baseline episode for CEE users in the observational study and relative to Women’s Health Initiative enrollment otherwise. Confounding factors in the observational study were controlled separately in the prior HT and no prior HT groups and are listed in the Materials and Methods section of the text.

^§

No. of cases among CEE users in the clinical trial/no. of cases among CEE users in the observational study that contribute to the hazard ratio estimate.