Dominic J. Cirillo, B.S., of the University of Iowa, Iowa City, and colleagues examined data from the Women's Health Initiative (WHI), which were two randomized, double-blind, placebo-controlled trials conducted at 40 U.S. clinical centers. The patient sample was 22,579 women aged 50 – 79 years without prior cholecystectomy (removal of the gallbladder). Women with hysterectomy were randomized to conjugated equine estrogens (CEE) or placebo (n=8,376). Women without hysterectomy were randomized to estrogen plus progestin (E+P, n=14,203).
Cholelithiasis (gallstones in the gallbladder) is estimated to affect between 10 percent and 15 percent of the U.S. population, with one million new diagnoses yearly. Researchers conducted this study to determine the effect of estrogen therapy in postmenopausal women on gallbladder disease outcomes.
The researchers found that both trials showed greater risk of any gallbladder disease or surgery with estrogen: 67 percent increased risk with use of CEE; 59 percent increased risk with use of E + P. Both trials indicated a higher risk for cholecystitis (inflammation of the gallbladder): 80 percent increased risk with CEE; 54 percent increased risk with E + P; and for cholelithiasis, a 86 percent greater risk with CEE; a 68 percent increased risk for estrogen users.
Among women with hysterectomy, CEE contributed to 31 excess events per 10,000 women annually. E + P contributed to an excess of 20 events per 10,000 women annually.
(JAMA. 2005;293:330-339. Available post-embargo at JAMA.com)
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