Researchers with the US National Institutes of Health have stopped a seven-year federal study of estrogen use by post-menopausal women after finding the therapy increased the risk of strokes, although it neither prevented nor caused heart disease.
However, the results, released yesterday by the NIH, were seen as positive for US drugmaker Wyeth, maker of hormone products including estrogen treatment Premarin, as the study did not find increased risks of cancer.
The study was the second part of the Women’s Health Initiative research on long-term hormone replacement therapy for post-menopausal women. The first, which studied a combination of estrogen and progestin, shocked the medical community and dramatically changed women’s use of HRT after the study was stopped in July 2002.
The first part, which used Wyeth’s combination therapy Prempro, linked the treatment to increased risk of heart attacks, strokes and breast cancer after five years’ use. That increased risk has slashed Wyeth’s HRT drug sales by 50 per cent from more than $2bn in annual sales expected in 2002 to about $1bn this year.
Wyeth’s Premarin was the focus of the second part, which sought to explore previous theories that hormones could help prevent heart disease in women over the long term.
Wyeth had already included labelling warning of possible increased stroke risk with Premarin.
The second study did not find increased risks of breast cancer or heart attacks – something that caused concern after the study on Prempro. Premarin, the NIH said, increased the relative risk of stroke by a similar degree as Prempro – eight more strokes per year in 10,000. It decreased the risk of hip fractures and did not increase the risk of breast cancer.