Venous Thromboembolic Events Associated With Hormone Replacement Therapy

To the Editor.  —The Heart and Estrogen-Progestin Replacement Study (HERS) is a randomized, double-blind, placebocontrolled trial designed to test the effect of hormone replacement therapy on the rate of new coronary heart disease (CHD) events in 2763 postmenopausal women younger than 80 years who had preexisting CHD and an intact uterus at enrollment. Participants were randomly assigned to take 1 tablet daily, either a placebo or the combination of 0.625 mg of conjugated equine estrogens and 2.5 mg of medroxyprogesterone acetate. Recruitment for HERS was completed in September 1994, and the trial is scheduled to continue until mid 1998.In addition to the primary end point of CHD events, a number of secondary end points were specified in the HERS protocol for evaluation in planned interim monitoring; these include the occurrence of venous thromboembolic events (VTE), ie, deep vein thrombosis, pulmonary embolism, or both.Recently, 4 observational studies^1-4 and