FRIDAY, July 11 (HealthDay News) -- Postmenopausal women using hormone replacement therapy (HRT) are at higher risk of gallbladder disease if they use oral rather than transdermal drugs, according to study findings published July 10 in BMJ Online First.
Bette Liu, Ph.D., and colleagues at the University of Oxford in Oxford, U.K., analyzed data from the Million Women Study of 1,001,391 postmenopausal women with a mean age of 56 years, of whom 19,889 were admitted to hospital with gallbladder disease and 17,190 underwent cholecystectomy.
Overall, current users of HRT were 1.64 times more likely than women who had never used it to have gallbladder disease, the investigators found. However, for those who used transdermal medication, the risk was only 1.17 times, versus 1.74 times for those on oral therapy. Thus, the use of transdermal HRT increased the risk of gallbladder disease by 1.3 percent, whereas oral therapy increases it by 2 percent, they note. However, transdermal HRT is more costly and can cause local skin reactions, the report indicates. Equine estrogens carried a slightly greater risk than estradiol among women taking oral HRT. The risk of gallbladder disease declined after HRT treatment ceased, the researchers report.
"For women who choose to use hormone replacement therapy, one cholecystectomy could be avoided for every 140 users of transdermal rather than oral therapy over a five-year period," the authors conclude.