HRT patches better than pills for gallbladder disease risk
11 Jul 08
Women using hormone replacement therapy (HRT) skin patches or gels have a lower risk of gallbladder disease than those taking HRT tablets, according to an Oxford University study published in the British Medical Journal today.
HRT is regularly prescribed to women suffering from the effects of the menopause. Approximately one million UK women took HRT in 2005, with the majority being given HRT pills.
Gallbladder disease is common in post-menopausal women and it is well known that use of HRT increases the risk. But until now there has been no assessment of whether this risk varies according to the method of administration, such as skin patches or gels compared with oral tablets.
Dr Bette Liu and colleagues from the Cancer Epidemiology Unit at the University of Oxford reviewed data from the Million Women Study, a national study on how various reproductive and lifestyle factors affect women’s health. The study has gathered information from more than 1.3 million UK women aged around 50–69 years.
The Oxford team report that after following the women for an average of six years, almost 20,000 women were admitted to hospital with gallbladder disease and just over 17,000 of them had to have their gallbladder removed (cholecystectomy).
Compared to women who had never taken HRT, the researchers found that women who used HRT had an increased risk of developing gallbladder disease. Importantly, they also found that women taking the HRT in a patch or gel form were substantially less likely to be admitted to hospital for gallbladder disease and less likely to have their gallbladder removed than the women taking HRT by oral tablets.
Hospital admission rates per 100 women over five years for cholecystectomy were 1.1 for women who had never used HRT, 1.3 for users of the patch or gel form of HRT, and 2.0 for the oral form of HRT.
The increased risk of gallbladder disease gradually decreased after use of HRT stopped. However, 10 years after stopping, the risk remained greater than in women who had never used HRT.
The researchers suggest that the difference in risk of developing gallbladder disease between HRT patches and pills might be due to the different way in which the hormone oestrogen is absorbed. When taken orally, much of the oestrogen is broken down by the liver before entering the circulation. In contrast, lower doses of oestrogens are given in HRT patches and the oestrogen is absorbed directly through the skin and into the circulation. This, say the authors, may explain the lower risk of gallbladder disease associated with the patch form of HRT.
'For women who choose to use hormone replacement therapy, one cholecystectomy could be avoided for every 140 users of transdermal therapy rather than oral therapy over a five year period', the researchers conclude.