Fewer gall bladder problems with HRT patch

A new study published on www.bmj.com reports that although hormone replacement therapy (HRT) results in an overall increase in risk of gallbladder disease, HRT administered by skin patches or gels poses a smaller risk than HRT given orally.

To study the different effects of HRT treatment given orally or through skin patches and gels, Dr Bette Liu (University of Oxford) and colleagues analyzed data from over 1.3 million UK women aged 50 to 69 years who participated in the Million Women Study. After an average of 6 years of follow-up, 19,889 women were admitted to a hospital with gall bladder disease, and 86% (17,190) of these required surgery to have the gall bladder removed (cholecystectomy).

Liu and colleagues confirmed previous results that indicated an increased risk of developing gallbladder disease for women receiving HRT compared to women who had never taken HRT. Regarding HRT administration methods, the researchers found that women who took HRT through a patch or gel were significantly less likely to require hospitalization for gallbladder disease and less likely to require cholecystectomy than women who received HRT in the form of tablets.

Specifically, gallbladder removal hospital admission rates per 100 women were 1.1 for women who never used HRT, 1.3 for patch or gel HRT users, and 2.0 for oral HRT users. After HRT terminated, there was a gradual reduction in the heightened risk of gallbladder disease. Still, however, even after 10 years of stopping treatment, women who had HRT still had a higher risk than women who had never had HRT.

The cause is probably differential oestrogen absorption. HRT given orally is broken down by the liver, while HRT administered through a patch is absorbed directly from the skin and generally provides a lower dose.