Newswise — Even though research has shown inexpensive treatments for high blood pressure are just as effective as pricey new drugs, doctors perceive the new drugs as more effective and think they carry fewer side effects, according to a new study by a University of Michigan Health System physician.

Diuretics and beta-blockers are recommended by the Joint National Commission on High Blood Pressure Treatment as the first-line treatment for uncomplicated high blood pressure. But in the survey of 1,700 primary care doctors, diuretics were rated less effective at lowering blood pressure and beta-blockers were thought to have more side effects than the newer calcium channel blockers and ACE inhibitors.

Further, doctors who favored prescribing the more expensive drugs were more likely to give patients free drug samples from pharmaceutical representatives.

"These new, more expensive medications are being more heavily promoted by the drug companies, and one way or another that information influences how people perceive the drug's effectiveness," says study author Peter A. Ubel, M.D., associate professor of internal medicine at the U-M Medical School and director of the U-M Health System's Program for Improving Health Care Decisions.

The study, published in the December issue of the Journal of General Internal Medicine, presented a hypothetical patient whose blood pressure was 170/105 (anything higher than 140/90 is considered abnormal). The patient had tried to control his blood pressure for a year using diet and exercise but it remained high. He has no other medical problems. Doctors were asked to estimate the effectiveness in this situation of ACE inhibitors, beta-blockers, calcium channel blockers and diuretics. They were also asked what medication they would initially prescribe for this patient.

Despite numerous clinical trials that have shown diuretics and beta-blockers to be equally effective in treating uncomplicated high blood pressure, the doctors surveyed rated diuretics significantly less effective than the other three drugs and felt beta-blockers were more likely to cause side effects. Doctors were most likely to recommend ACE inhibitors as their first treatment choice.

When diabetes or heart disease accompanies hypertension, ACE inhibitors are a good choice, Ubel says. But for the hypothetical patient, there would be no advantage to taking ACE inhibitors over diuretics or beta-blockers. Ubel suggests doctors might be getting into a habit of prescribing the more expensive medications, forgetting when to use the generics.

In fact, ACE inhibitors tend to have more side effects than diuretics or beta-blockers. They're also more expensive, which could drive up the patient's bill at the drug store " or ultimately drive up insurance costs.

Doctors who recommended ACE inhibitors or calcium channel blockers were much more likely to provide patients with free drug samples provided by the pharmaceutical companies. They were also more likely to be in solo or private practice, rather than public or academic medical settings. They had practiced medicine longer and reported spending more hours each week on patient care.

Pharmaceutical representatives often visit doctors' offices to introduce them to the latest drugs and provide free samples. Many drug companies also sponsor continuing medical education courses, which are required for doctors to maintain their certification.

"The industry influence is pervasive," says Ubel, who is also a research investigator at the Ann Arbor Veterans Administration Health Center. "I think a lot of physicians do rely on sales representatives to tell them about the latest medications out there. How else do you find this out? It is very hard to keep up on the medical literature. Doctors feel it's an educational visit, but the sales reps hand out samples."

The University of Michigan Hospitals and Health Centers prohibits distributing drug samples to patients.

"It may seem like the doctor's helping patients get more affordable medicine, but it's not a lifetime supply. After the free samples run out, the patient is left to pay for a more expensive drug," Ubel says.

In addition to Ubel, study authors were Christopher Jepson, Ph.D., and David A. Asch, M.D., MBA, both from the University of Pennsylvania School of Medicine. Ubel is supported by a Presidential Early Career Award for Scientists and Engineers. This study was also supported by the Matthew Slap Foundation and the National Cancer Institute.

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Journal of General Internal Medicine (Dec-2003)