HRT tablets highest VTE risk
Thursday January 10th, 2019
Women who take hormone replacement therapy in tablet form may face an increased risk of venous thromboembolism, according to a large UK study published today.
Researchers at Nottingham University say their findings highlight the risks associated with different delivery methods. They found increased risk from HRT delivered by patches, gels or creams.
GP leaders said the findings did not prove that tablets caused an increased risk – only a link.
The study, reported by The BMJ, involved an analysis of the records of more than 2,000 GP practices over a period of 18 years.
The research spanned a time of major changes in prescribing practices as a result of evidence about the risks of HRT that emerged at the beginning of the century.
The researchers found that women taking tablets had twice the risk of suffering VTE compared with those taking other forms of treatment. This is equivalent to nine extra cases among 10,000 women annually.
The researchers say that 80% of HRT treatments continue to be given in tablet form.
There was also a difference in risk between different kinds of tablets. There was a 15% greater risk from HRT derived from horses compared with synthetic oestradiol.
The study compared more than 80,000 women who developed VTE with another 390,000 women who did not.
Researcher Dr Yana Vinogradova, of Nottingham University medical school, said: "Our study has shown that, for oral treatments, different tablets are associated with different risks of developing blood clots, depending on the active components. It has also confirmed that risks of thrombosis for patients using HRT treatments other than tablets (patches or gels) is very low.
“This lower risk has been known for more than ten years and - although patches or gels may not be acceptable in some circumstances - it was surprising to find that only 20% of HRT prescriptions to date have been for non-oral treatments. Our findings are particularly important information for women, who require HRT treatment and are already at increased risk of developing blood clots."
The UK Royal College of GPs said patients should not panic.
Chair Professor Helen Stokes-Lampard said: “While this study is certainly interesting and important, as the authors themselves acknowledge, the findings do not prove that tablets cause more DVTs than patches, just that there is an association. As such, it is essential that more research is conducted in this area, and taken into account, as new clinical guidelines are updated and developed.
“Prescribing is a core skill for GPs and current best practice is to prescribe the lowest possible dose of HRT for the shortest possible time, and so specific products and formulations of HRT are only initiated after a comprehensive discussion between the GP and their patient - and are tailored to meet the best interests of that individual.”
Use of hormone replacement therapy and risk of venous thromboembolism: nested case-control studies using the QResearch and CPRD databases. BMJ 10 January 2019
http://www.bmj.com/content/364/bmj.k4810
Tags: Heart Health | Pharmaceuticals | UK News | Women's Health & Gynaecology
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