The increase in the use of calcium channel blockers and ACE inhibitors for the treatment of hypertension -- a 10-year trend that is not supported by research studies or national treatment guidelines -- has been paralleled by a marked increase in advertising such drugs to physicians, says a research group from the Massachusetts General Hospital (MGH). Although their findings, published in the April 20 issue of Circulation, cannot prove that advertising has influenced how physicians choose which drugs to prescribe, the authors believe pharmaceutical marketing efforts may help explain the switch away from older, less expensive medications such as beta blockers and diuretics.
"We were surprised to see how striking the increase in advertising was during the years we studied," says Thomas J. Wang, MD, a senior medical resident at the MGH and the paper's first author. "The total number of ad pages for calcium channel blockers nearly quadrupled, making them the most heavily advertised medication of any type of during 1996, a year during which we found no ads at all for diuretics or beta blockers."
He adds, "There are a lot of competing influences on how physicians treat their patients, and these can include commercial as well as scientific influences. At this time, the available scientific data favor the use of the older medications -- beta blockers and diuretics -- for uncomplicated hypertension. That may change as more studies are completed with these newer medications, but until that time it is reasonable to consider the older medications as first-line therapy for most patients who need help controlling their blood pressure."
Hypertension or high blood pressure affects more than 50 million Americans and is a significant risk factor for heart disease and stroke. While many people can control their blood pressure through such lifestyle changes as reducing sodium intake and losing weight, some need to use medication to keep their blood pressure at safe levels. The most established of these antihypertensive drugs are diuretics, which rid the body of excess fluids and salts, and beta blockers, which reduce the heart rate and its output of blood. The study's authors note that these drugs -- which now are available in low-cost, generic versions -- are the only blood pressure medications proven in large-scale studies to reduce deaths from cardiovascular disease.
Two of the newer classes of drugs are ACE (angiotensin-converting enzyme) inhibitors, which interfere with production of a chemical that constricts arteries, and calcium channel blockers, which reduce the heart rate and relax blood vessels. In spite of the scientific evidence favoring the older drugs, the use of the newer calcium channel blockers and ACE inhibitors has increased dramatically since the mid-1980s. In 1995, for example, calcium channel blockers accounted for 38 percent of antihypertensive prescriptions, ACE inhibitors were prescribed 33 percent of the time, but beta blockers and diuretics were prescribed only 19 percent of the time.
"There is a good amount of information suggesting that physicians aren't following the national guidelines for treating hypertension, which call for beta blockers and diuretics to be used as first-line treatment for most patients," says Randall Stafford, MD, PhD, of the MGH Institute for Health Policy and General Medicine Division and the study's senior author. "We wanted to investigate other factors that might be behind that trend, particularly whether advertising might have an effect."
The research team, which also included John Ausiello of the MGH General Medicine Division, analyzed the January, April, July and October issues of the New England Journal of Medicine from 1985 through 1996 to determine the proportion of total ad pages devoted to particular classes of medication. They found that ads for calcium channel blockers increased from 4.6 percent of pages in 1985 to 26.9 percent of pages in 1996, while ads for beta blockers decreased from 12.4 percent to 0 percent and ads for diuretics decreased from 4.2 percent to 0 percent. Ads for ACE inhibitors increased from 3.5 percent to 4.3 percent, a change that was not statistically significant.
"Physicians who have been surveyed claim that advertising has little effect on their practice patterns, but common sense suggests that pharmaceutical companies would not spend the money they do if they didn't have evidence of its effectiveness," Stafford says. "We certainly do not suggest that anyone stop taking a medication that is working for them or question their physician's decisions, but patients who are about to start medication may want to discuss the benefits of the various types of drugs with their doctors before deciding on their individual treatment plans."
One previous study comparing the costs of these therapies found that a month of treatment with calcium channel blockers cost twice as much as beta blocker treatment and 20 times as much as diuretic treatment. The current study was supported by a grant from the Agency for Health Care Policy and Research.