Study Shows that Blood Pressure Drug Lowers Risk of Cardiovascular Disease

Chlorthalidone, a common diuretic used to treat people with high blood pressure, dramatically decreases the risk of cardiovascular disease compared to doxazosin, an alpha-blocker, say researchers at The University of Texas-Houston Health Science Center.

The findings were reported by UT-Houston School of Public Health researchers as part of the Antihypertensive and Lipid-Lowering Treatment to Prevent Heart Attack Trial (ALLHAT), which is an eight-year, multi-center study funded by the National Heart, Lung, and Blood Institute (NHLBI). The study results were published in the April 19 issue of The Journal of the American Medical Association.

"We showed that study participants who took chlorthalidone cut their risk of heart failure in half, compared to those who took doxazosin," says Dr. Barry R. Davis, professor of biometry at UT-Houston School of Public Health and deputy director of the school's Coordinating Center for Clinical Trials.

ALLHAT researchers want to know if cheaper drugs, such as diuretics, are better in combating high blood pressure and its adverse side effects, including heart attack and stroke.

The study followed 24,335 patients age 55 and older with high blood pressure and at least one of several cardiovascular disease risk factors, such as diabetes and a history of stroke. The patients were randomly assigned to receive one of four high blood pressure drugs, including chlorthalidone and doxazosin.

"The doxazosin group had a 25 percent increased risk for cardiovascular disease and a doubled risk for heart failure compared with the chlorthalidone group," says Dr. Davis.

The NHLBI halted the doxazosin part of the study early based on the findings.

Dr. Davis says the study may lead to better therapies for older patients with high blood pressure.

"Our study results proved that at present, chlorthalidone should be the first line of defense in treating older adults with high blood pressure at risk for heart disease," Dr. Davis says.

UT-Houston School of Public Health was awarded a $103.2 million contract from the NHLBI to coordinate ALLHAT in 1993, making it the largest contract ever awarded to UT-Houston.

More than 4.6 million Americans suffer from heart failure, a leading cause of disability and death in the U.S., and is the most common hospital discharge diagnosis among people age 65 and older.

More than 50 million Americans have high blood pressure, or hypertension. The disease is 50 percent more prevalent in African-Americans than whites.

- JACKIE PRESTON

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©2006 Texas Medical Center

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