By Mark Pownall
Low dose hormone replacement patches do not increase the risk of stroke but oral therapy does, according to a UK study.
The study looked at 12,782 women aged 50-79 registered on the general practice research database, who had a stroke between 1987 and 2004, and compared those on oral, transdermal and no HRT. Researchers found a 28% increased risk of stroke in women who were on oral HRT, but no increase for women on low-dose patches – 50 micrograms or less.
Study lead Dr Christel Renoux, a researcher at the McGill pharmacoepidemiology research unit in Montreal, said this is the first study to investigate the route of HRT administration on the risk of stroke.
He said: ‘Use of low dose transdermal oestrogen replacement therapy with or without progestogen was not associated with an increased risk of stroke, although a slightly increased risk with long term use cannot be excluded.’
Patches avoid hepatic metabolism of the drug and the subsequent induction of clotting factors and inflammatory markers added Dr Rentoux and studies have found fewer metabolic changes in women taking transdermal HRT compared to those taking oral treatment.
BMJ online first June 3
HRT patches have lower risk of stroke than pills