The study, of 27,000 women who used transdermal hormone replacement therapy (HRT) and 27,000 matched controls taking oestrogen-only pills, found that those who used oestrogen patches were one-third less likely to develop deep vein thrombosis or pulmonary embolism.
But more importantly, the current study gives a snapshot of what's going on in the "real world", according to lead researcher Patrick Lefebvre, of Analysis Group, Inc. in Montreal, Canada.
Most of what's been known about the blood clot risks of oestrogen patches has come from clinical trials, Lefebvre said.
The current findings are based instead on health insurance claims from just over 54,000 women who used HRT at some point between 2002 and 2009.
The study, published online in Menopause, "corroborates the literature with data from the real-world setting", Lefebvre said.
Patches bypass the liver
Analysis Group, Inc. conducted the study with funding from Novartis Pharmaceuticals, a maker of hormone therapy patches.
Researchers think hormone patches may be less risky than pills because they bypass the liver and may not boost clot-promoting proteins in the blood.
In the current study, women used hormone therapy for just over a year, on average.
Of the women who used oestrogen-only pills, 164 developed venous thromboembolism, for an annual rate of almost 0.6%. Of the women who used oestrogen patches, 115 had a venous thromboembolism, or 0.4% per year.
Coupled with past studies, the new findings suggest that for women who want to try hormones to ease hot flashes, patches could be a safer alternative.
Patches are expensive
However, the patches tend to be more expensive than the pills, which usually cost less than R100 a month for generic versions.
But Lefebvre said the bottom line for women is to be aware that there are different options for managing menopausal symptoms. "The decision on how to treat must be an individual one."
Some women may be able to ease hot flashes with simple changes, like sleeping in a cool room and watching their intake of caffeine, alcohol and hot, spicy foods. There's also some evidence that yoga, meditation or other relaxation techniques can be helpful.
In some cases of more-bothersome hot flashes, low doses of certain antidepressants can help. Vaginal dryness, another common menopause symptom, may be treatable with topical oestrogen.
As for alternative remedies for hot flashes, some studies have suggested that soy, black cohosh and other sources of phytoestrogens (plant-based oestrogen-like chemicals) may help; other studies, however, have found no such benefit.
(Reuters Health, Amy Norton, September 2011)