WEDNESDAY, April 16, 2003 (HealthDayNews) -- Estrogen delivered to postmenopausal women in patch rather than pill form doesn't raise blood levels of a protein associated with higher heart disease risk, a research team has found in a small study.
However, it's too soon to say the patch is a safer form of hormone therapy, says Dr. Wanpen Vongpatanasin, a cardiologist at the University of Texas Southwestern Medical Center. She is the principal investigator of the study, which appears in the April 16 issue of the Journal of the American College of Cardiology.
The study included only 21 women and looked simply at a marker of heart disease, but did not compare long-term effects of the different therapy forms.
The Women's Health Initiative (WHI) study was halted last year due to higher risks of heart disease and stroke found in women on oral hormone replacement therapy compared to those not taking it. Since then, researchers have continued to analyze the health effects of hormone therapy, investigating whether different formulations or delivery methods might carry fewer risks.
In the new study, Vongpatanasin and her colleagues from the University of California at Davis Medical Center took baseline levels of the participants' C-reactive protein, a marker of inflammation that predicts heart attack and heart disease.
Then, the women were rotated among three treatments -- the patch, oral estrogen and placebo, taking each for eight weeks and having their C-reactive protein measured before and after. When they were on the active patch, they were given a dummy pill; when they were on the active pill, they got a dummy patch. And while on placebo, both pill and patch were dummies.
"The pills raised the C-reactive protein by more than twofold, whereas when the women were on the patch or on placebo, there was no change," Vongpatanasin says. But the blood levels of estrogen were similar with pill and patch.
The rise in C-reactive protein while on the oral form of hormone therapy is not surprising, Vongpatanasin says. The finding has been reported in other studies, including the WHI.
In a recent study evaluating more than 27,000 women, reported in The New England Journal of Medicine, high levels of C-reactive protein were found to be a more accurate predictor of heart disease than high levels of so-called "bad" cholesterol, LDL.
Exactly why oral estrogen drives up C-reactive protein is not known, Vongpatanasin says. "C-reactive protein is produced mainly by the liver," she explains. While oral estrogen is processed through the liver before circulating to other areas in the body, estrogen delivered by patch enters the bloodstream directly.
When delivered by patch, the amount of estrogen is less than in pill form, Vongpatanasin says. In the study, the patch delivered a maximum of 100 micrograms of estrogen a day, while the pill delivered 625 micrograms.
In her study, Vongpatanasin also found that oral estrogen, but not the patch form or the placebo treatment, suppressed the women's blood levels of insulin-like growth factor, IGF-1, a substance that fights inflammation.
The study is interesting, says Dr. Cynthia A. Stuenkel, an associate physician in family and preventive medicine at the University of California, San Diego, but it's not enough proof to say for sure that the patch has no risks. It's been reported previously that oral estrogen increases C-reactive protein and that the patch doesn't, "but this is the first head-to-head comparison."
However, C-reactive protein is simply a marker for heart disease. It's known that a high baseline level of C-reactive protein puts you in a higher risk category for heart disease. "But it remains to be proven whether an increase in C-reactive protein from taking oral estrogen is associated with an increased risk of heart disease," Stuenkel says.
Another expert, Dr. Ravi Dave, a cardiologist at the Santa Monica-UCLA Medical Center in California, says that while the study is small, "the concept and hypothesis they used are very sound."
He adds more study is needed, but that "estrogen might not be as bad as it was thought to be in terms of cardiovascular risk." Women who are likely to benefit from supplementary estrogen, such as for short-term hot flash relief or osteoporosis reduction, he says, may have an option in the patch.
More information
For information on hormone therapy, try the National Institutes of Health. For information on C-reactive protein, go to Medline plus.
