A multicenter study of a pill that combines two drugs for hypertension shows significant benefit for people with hard-to-control high blood pressure.
The study, conducted at the University of Maryland School of Medicine and 118 other sites, was focused on bringing down systolic blood pressure, the top number in a blood pressure reading, which is the more difficult number to bring down. The results of the study, called the INCLUSIVE trial, will be presented at the American Society for Hypertension conference in San Francisco on Tuesday, May 17, 2005.
"The percentage of patients whose blood pressure was controlled in this study was much higher compared to other combination therapy trials," says one of the study's two principal investigators, Elijah Saunders, M.D., professor of medicine at the University of Maryland School of Medicine and a cardiologist and hypertension expert at the University of Maryland Medical Center.
"This was the first large-scale hypertension study to include such a broad range of patient groups," says Dr. Saunders. "We found that this combination therapy reduced systolic blood pressure to a desirable level in 77 percent of the patients, and 83 percent of the patients in our study achieved an acceptable diastolic blood pressure. These results are significant," he adds.
The study began with a total of 1,005 participants with high blood pressure. A broad range of people participated in the study in terms of age and ethnicity. Half of them were women. All were given a diuretic alone for two weeks at the start of the trial. Nearly 30 percent of participants responded to this one drug, so they were eliminated from further participation. The remaining 736 people were given the combination pill of irbesartan (an angiotensin II receptor blocker) and a diuretic, hydrochlorothiazide, in increasingly stronger doses until their blood pressure reached a desirable goal. At the end of 18 weeks, the participants' systolic blood pressure (the top number) dropped an average of 21.5 points, from 154.4 to 132.9 points. Their diastolic blood pressure (the bottom number) fell an average of 10.4 points, from 91.3 to 80.9.
Current national guidelines recommend that blood pressure be kept below 140/90 millimeters of mercury for the general population, and less than 130/80 for people with diabetes or chronic kidney disease. Hypertension increases the risk of coronary heart disease, heart attack and stroke.
The study included at least 100 hypertensive patients in specific subgroups: those age 65 and older, African-Americans, Hispanic/Latinos, and people with type 2 diabetes. Patients with several risk factors for cardiovascular disease were also included, such as obesity, abnormal glucose tolerance, high triglycerides and low high-density lipoprotein, the so-called "good" cholesterol. According to Dr. Saunders, all of these subgroups represent a large part of the hypertensive population in the U.S. They may require two or more medicines to reach a desirable blood pressure goal.