Estrogen-based hormone therapy in women with primary ovarian insufficiency: a systematic review

Sex hormones play a role in bone density, cardiovascular health, and wellbeing throughout reproductive lifespan. Women with primary ovarian insufficiency (POI) have lower estrogen levels requiring hormone therapy (HT) to manage symptoms and to protect against adverse long-term health outcomes. Yet, the effectiveness of HT in preventing adverse outcomes has not been systematically assessed. We summarize the evidence regarding effects of HT on bone and cardiovascular health in women with POI.

A comprehensive search of the electronic databases MEDLINE, EMBASE, and Scopus was conducted by a medical reference librarian from database inception to January 2016. Randomized trials and observational cohort studies with an estrogen-based HT intervention in women with POI under the age of 40 were included. Reviewers worked independently and in duplicate to assess eligibility and risk of bias, and extract data of interest from each study.

The search identified 1670 articles; 12 met inclusion criteria. Four randomized clinical trials and eight cohort studies at high risk of bias enrolled 806 women with POI. The most common HT formulations were transdermal estradiol and oral conjugated equine estrogen combined with medroxyprogesterone acetate. Bone mineral density was the most frequent outcome, with three out of eight studies showing HT associated increase benefits. Only one study reported effects on fractures or vasomotor symptoms and none on cardiovascular mortality. Results regarding lipid profiles were inconsistent.

Evidence supporting bone and cardiovascular benefits of HT in women with POI is limited by high risk of bias, reliance on surrogate outcomes, and heterogeneity of trials regarding the formulation, dose, route of administration, and regimen of HT. Further research addressing patient important outcomes such as fractures, stroke, and cardiovascular mortality are crucial to optimize benefits of this therapy.