The association of hormone therapy with blood pressure control in postmenopausal women with hypertension: a secondary analysis of the Women's Health Initiative clinical trials.

Objective: The objective of this study was to assess the effect of menopausal hormone therapy (HT) on blood pressure control in postmenopausal women with hypertension.

Methods: The Women's Health Initiative HT clinical trials were double-blinded, randomized, placebo-controlled studies of women aged 50 to 79 years testing the effects of HT (conjugated equine estrogens [CEE, 0.625 mg/d] or CEE + medroxyprogesterone acetate [MPA; 2.5 mg/d]) on risks for coronary heart disease and invasive breast cancer, the primary outcomes for efficacy and safety, respectively. This secondary analysis of the Women's Health Initiative HT trials examined a subsample of 9,332 women with hypertension (reported ever taking pills to treat hypertension or were taking antihypertensive medication) at baseline. Blood pressure was measured at baseline and up to 10 annual follow-up visits during the planned study phase. Antihypertensive medications were inventoried at baseline and years 1, 3, 6, and 9 during the study, and self-reported during extended follow-up: 2009-2010 and 2012-2013, which occurred median of 13 and 16 years after randomization, respectively. The intervention effect was estimated through year 6. Cumulative follow-up included all visits.

Results: Compared with placebo, CEE-alone had significantly ( P = 0.02) higher systolic blood pressure (SBP) by mean (95% confidene interval [CI]) = 0.9 (0.2-1.5) mm Hg during the intervention phase. For cumulative follow-up, the CEE arm was associated with increased SBP by mean (95% CI) = 0.8 (0.1-1.4) mm Hg ( P = 0.02). Furthermore, CEE + MPA relative to placebo was associated with increased SBP by mean (95% CI) = 1.8 (1.2-2.5) mm Hg during the intervention phase ( P < 0.001). For cumulative follow-up, the CEE + MPA arm was associated with increased SBP by mean (95% CI) = 1.6 (1.0-2.3) mm Hg ( P < 0.001). The mean number of antihypertensive medications taken at each follow-up visit did not differ between randomization groups during the intervention or long-term extended follow-up of 16 years.

Conclusion: There was a small but statistically significant increase in SBP in both CEE-alone and CEE + MPA arms compared with placebo during both the intervention and cumulative follow-up phases among postmenopausal women with hypertension at baseline. However, this increase in SBP was not associated with an increased antihypertensive medication use over time among women randomized to HT compared with placebo.