Background: Hormone therapy plays an important role in the clinical management of menopausal symptoms. Because of an increased risk of harms, hormone therapy is currently not recommended for the primary prevention of chronic conditions.
Purpose: To update evidence on the effectiveness of hormone therapy in reducing risk of chronic conditions, its adverse effects, and differences among population subgroups for the U.S. Preventive Services Task Force.
Data Sources:
We searched MEDLINE, the Cochrane Library, and Embase for English-language articles (through August 1, 2016). We conducted searches for unpublished literature by searching
Study Selection: We dually reviewed the literature and included randomized, placebo-controlled trials that provided information on the primary prevention of chronic conditions with hormone therapy and reported health outcomes.
Data Extraction: We abstracted details about participants, study design, analysis, followup, and results; study quality and strength of evidence were rated using established criteria.
Data Synthesis: Seventeen fair-quality trials met eligibility criteria. The Women's Health Initiative (WHI) was the largest study and most applicable to the target population.
Results of our review indicate differences in the risk-benefit profile between treatment formulations. Women using estrogen only had statistically significantly lower risk (per 10,000 women over 6.8 to 7.2 years) of diabetes (137 fewer cases) and fractures (382 fewer cases) than women taking placebo. However, risk (per 10,000 women over 5.4 to 7.1 years) was statistically significantly increased for gallbladder disease (213 more cases), stroke (79 more cases), and venous thromboembolism (78 more cases). The risk of urinary incontinence (1,261 more cases per 10,000 women) was increased during a followup of 1 year.
Women using estrogen plus progestin therapy experienced statistically significantly lower risk (per 10,000 women over 5.0 to 5.6 years) for colorectal cancer (33 fewer cases), diabetes (77 fewer cases), and fractures (222 fewer cases) than women taking placebo. Risk (per 10,000 women over 4 to 5.6 years) of invasive breast cancer (52 more cases), probable dementia (88 more cases), gallbladder disease (116 more cases), stroke (53 more cases), and venous thromboembolism (120 more cases) was statistically significantly increased compared with women taking placebo. The risk of urinary incontinence (876 more cases per 10,000 women) was increased during a followup of 1 year.
Limitations: Few trials or subgroup analyses were powered for prevention outcomes. No comparative evidence on type, dose, and mode of delivery of hormone therapy is available. The applicability of results to younger women who initiate hormone therapy for the management of menopausal symptoms and to women with nonwhite ethnic backgrounds might be limited.
Conclusions: Women undergoing hormone therapy for the primary prevention of chronic conditions experience some beneficial effects but also an increased risk of harms.