Baseline use of aspirin or statins with oral estrogen and progestogens to prevent incident arterial or venous thrombotic events: a secondary analysis of the Women's Health Initiative trial.

OBJECTIVE

To evaluate whether effects of oral hormone therapy (HT) on risks of venous and arterial vascular events differ by baseline statin or aspirin use.

METHODS

We performed time-to-event analysis using data from the Women's Health Initiative menopausal HT randomized trials to assess risk of thrombotic events. Women were randomized to oral conjugated equine estrogens (CEEs) alone or placebo among women with prior hysterectomy (n = 10,739), and CEE with medroxyprogesterone acetate (MPA) or placebo among women with an intact uterus (n = 16,608), stratified by baseline personal use of statins and aspirin. We evaluated risk of prespecified, adjudicated thrombotic events, including coronary heart disease, stroke, venous thromboembolism, and/or composite major adverse cardiovascular events, at 2 and 5 years.

RESULTS

Baseline statin use (n = 827 in CEE-alone trial; n = 1,115 in CEE+MPA trial) or aspirin use (n = 2,212; n = 3,431) was limited. At 5-year follow-up, coronary heart disease risk for CEE-alone versus placebo was hazard ratio (HR) = 0.81 (95% CI: 0.44-1.49) in statin users, similar to nonusers, HR = 1.07 (95% CI: 0.82-1.40). For CEE+MPA, there was also no difference by statin use, HR = 1.02 (95% CI: 0.55-1.89) and HR = 1.47 (95% CI: 1.13-1.90), respectively. Neither statin nor aspirin exposure significantly modified effects of HT on any arterial or venous thrombotic outcome at 2 or 5 years.

CONCLUSIONS

In this secondary randomized clinical trial analysis, neither statins nor aspirin significantly modified effects of oral HT on key arterial or venous thrombotic outcomes at 2 or 5 years. Results, however, may be underpowered given low baseline exposure prevalence for both statins and aspirin.