TUESDAY, Jan. 6, 2004 (HealthDayNews) -- Doctors are paying attention to the results of clinical trials and changing their prescribing patterns accordingly.
That's the conclusion of two studies in the Jan. 7 issue of the Journal of the American Medical Association.
Since recent reports have revealed hormone replacement therapy and alpha blockers might have detrimental effects, prescriptions for both have declined significantly, the researchers note.
"Physicians are human, occasional self-delusions to the contrary notwithstanding," says Dr. David Naylor, author of an accompanying editorial in the journal and dean of medicine at the University of Toronto. "The neat thing about these two studies is that they both give us a window on what happens when there are negative findings in clinical trials. They look at how physician prescribing changes when there's bad news about what were apparently good drugs. These studies do provide a reassuring message to the public about professional responses."
Hormone replacement therapy had increased dramatically over the past 20 years due to beliefs about its health benefits for postmenopausal women. Much to consumers' and physicians' surprise, recent randomized trials found the therapy involved an increased risk of breast cancer, cardiovascular disease and other problems.
Using two databases, the study authors determined that annual hormone therapy prescriptions in the United States increased from 58 million in 1995 to 90 million in 1999, then stayed level through June 2002. But after the disturbing results of the Women's Health Initiative were published in July 2002, prescriptions started declining significantly. Between January and June 2003, prescription for Prempro, the most popular product, declined 66 percent, and for Premarin, 33 percent.
Prescriptions of doxazosin, an alpha blocker, a class of drugs designed to lower blood pressure, followed a similar trajectory, albeit less dramatically.
In the spring of 2002, the doxazosin arm of the Antihypertensive and Lipid-Lowering Treatment to Prevent Heart Attack Trial (ALLHAT) was terminated early after finding the risk of "cardiovascular events" was 25 percent greater in patients receiving doxazosin than in patients being treated with a thiazide diuretic. Steady increases in new alpha blocker prescriptions turned into a decrease of 26 percent between 1999 and 2002.
A research letter in the same issue of this week's journal found an increase in prescriptions of thiazide-type diuretics to treat high blood pressure after the halting of the ALLHAT arm.
Why the difference in the level of prescription responses to hormone therapy and to alpha blockers?
"[The hormone study] received an incredible amount of media attention, really unprecedented. And, to me, that indicates that for physicians to really fully respond to clinical evidence, the discussion of the issues needs to leave the professional arena and become a topic of public conversation," says Dr. Randall S. Stafford, an author on both of the latest studies.
"The role of the media and the public in facilitating this sort of change is often underestimated," adds Stafford, an assistant professor at Stanford University Medical School's Stanford Prevention Research Center.
The two new studies do raise questions about how physicians obtain their information on the current state of scientific research.
"It's incredibly hard for physicians to stay up on all the areas they're expected to have expertise in, and that may be one of the explanations as to why a change of the magnitude observed for hormone therapy almost had to leave the professional arena," Stafford says.
Another issue is the difference between negative and positive study results in clinical trials. The tendency in medicine, as in the pharmaceutical industry, is to focus on what is new and positive.
"We want to do what is best for patients," Naylor says. "There is an optimistic bias built in to being a physician."
Needless to say, most drug companies also prefer to focus on positive results.
"The marketing forces at work here are formidable, and that's why [these new findings about prescribing patterns are] good news for the general public," Naylor adds. "Here's evidence that physicians make changes when the tide turns against what were thought of as good drugs."
More information
For more on hormone therapy, visit the National Women's Health Information Center. The American Heart Association has more on alpha blockers and other drugs that lower blood pressure.
