A team from the USA determined the effect of hormone replacement therapy on the risk for biliary tract surgery, in postmenopausal women with known coronary artery disease.
Previous animal and observational epidemiologic studies have reported that estrogens may increase the risk for gallstones.
A total of 2253 postmenopausal women were enrolled in the Heart and Estrogen/progestin Replacement Study (HERS), at 20 US clinical centers. All had a gallbladder, and were between the ages of 44 and 79 years.
In the randomized trial, subjects were given conjugated equine estrogens, 0.625 mg, plus medroxyprogesterone acetate, 2.5 mg, daily in one tablet, or identical placebo.
Some 147 women (7%) were hospitalized for biliary tract surgery in HERS.
| Women on HRT were 38% more likely to have biliary tract surgery.
| Annals of Internal Medicine |
Treatment with estrogen plus progestin resulted in a marginally significant 38% increase in the relative risk for biliary tract surgery.
A small absolute difference in risk suggested that, for every 185 women treated with estrogen plus progestin, one additional woman had biliary tract surgery per year.
After adjustment for baseline and in-study statin use, the association was attenuated further.
Following adjustment for treatment assignment and other variables, increased body mass index, fibric acid use, and a history of non-surgical gallbladder disease were associated with an increased risk for biliary tract surgery. Statin use was associated with a decreased risk.
Dr Joel A. Simon, of the Veterans Affairs Medical Center, San Francisco, California, concluded on behalf of his fellow authors, "Estrogen plus progestin therapy among postmenopausal women with known coronary disease resulted in a marginally significant increase in the risk for biliary tract surgery."