Study design

Gallstone disease is common in devel-oped countries,1 and complications ofgallstones represent a major reason for hospital admission and greatly contribute to health care costs and patient morbidity.2 Among women, those over 50 years of age are at great-est risk of gallstone disease.3 Other known risk factors are obesity, multiparity, dyslipidemia, hyperinsulinism, inappropriate dietary intake and genetic predisposition.4−8 Studies in the United States and the United Kingdom have reported an increased risk of cholecystectomy among women exposed to menopausal hor-mone therapy.9−14 No data are available in France, where menopausal hormone therapy regimens are different from those most com-monly used in the US and UK (predominance of the transdermal over oral route, infrequent use of equine estrogens, and frequent use of progesterone and its isomer, dydrogesterone, as the progestagen component). In addition, the impact of progestagens used in menopausal hormone therapy regimens remains unclear with regard to gallstone risk. We prospectively evaluated the risk for chole-cystectomy among women exposed to different menopausal hormone therapy regimens in a French cohort study