Decreased risk for gallbladder disease with use of transdermal vs. oral HT

Hormone therapy may increase the risk for gallbladder disease in postmenopausal women, according to recent data.

Researchers from the University of Oxford in the United Kingdom conducted a prospective cohort study to determine the difference between transdermal and oral HT in the risk for gallbladder disease.

The study included 1,001,391 postmenopausal women recruited from National Health Service breast screening centers. Mean age of participants was 56 years. Researchers followed the participants for a mean of 6.1 person years.

Thirty-two percent of participants were current users of HT (77% oral; 18% transdermal; 5% other), and 18% were past users.

During follow-up, 19,889 women were admitted for gallbladder disease; of these women, 17,190 had a cholecystectomy. The risk for gallbladder disease was greater in current HT users (RR=1.64; 95% CI, 1.58-1.69), compared with past users (RR=1.27; 95% CI, 1.22-1.32; P<.001). Risk for gallbladder disease was greater for those women taking oral HT, compared with those taking transdermal (P<.001).

As time since last use increased, the risk for gallbladder disease decreased among past users (P=.004); however, the risk remained greater among women who discontinued use more than 10 years prior, compared with never users.

Among oral HT users, equine estrogens were linked to a greater risk, compared with estradiol (P<.001).

BMJ. 2008;337:a386.