Non-confounded randomised controlled trials (RCTs) of HRT versus no HRT (open or placebo-controlled) in women were eligible for inclusion. Trials had to report event rates for one or more of cerebrovascular disease (stroke, transient ischaemic attack), coronary heart disease (myocardial infarction, unstable angina, cardiac death) and venous thromboembolism (pulmonary embolism, deep vein thrombosis).
Most trials studied progesterone and/or oestrogen (but some studied raloxifene) using a range of doses, and most were of vascular prevention, but nearly a third of trials were in patients with prior coronary heart disease. Mean ages of included participants ranged between 47 and 75 years (median 62.7 years). Women with a range of diagnoses were included, but healthy populations were the commonest to be studied.
The authors did not state how the papers were selected for the review, or how many reviewers performed the selection.