Scientists at The University of Texas Health Science Center in Houston say that a recent study conducted by them supports the findings reported in 2002 that a diuretic drug, or "water pill", outperforms other medications for high blood pressure.
High blood pressure is known to be associated with a host of health problems, including heart failure, coronary heart disease, stroke, and kidney failure. In adults, it is defined as 140/90 mm Hg or above.
The Antihypertensive and Lipid-Lowering Treatment to Prevent Heart Attack Trial (ALLHAT), the largest high blood pressure treatment trial ever conducted, compared the impact of four classes of blood pressure drugs on 42,418 high-risk patients between 1994 and 2002.
"We looked at data since the trial ended to make sure our message hasn't changed. And, it hasn't. Diuretic drugs work as well or better than other medications in preventing heart failure," said Dr. Barry Davis, study co-author, Guy S. Parcel Chair in Public Health and director of the Coordinating Center for Clinical Trials (CCCT) at The University of Texas School of Public Health.
The research points out that diuretic drugs reduce blood pressure by clearing the body of excess fluid and sodium.
In the ALLHAT study, diuretic drugs were compared to angiotensin-converting enzyme (ACE) inhibitors that widen blood vessels and decrease resistance, calcium channel blockers that relax vessels by slowing the flow of calcium into the heart and alpha blockers, which also relax blood vessels.
The thiazide-type diuretic used in that study was not only found to provide superior protection against new-onset heart failure, but was also observed to be superior to the alpha blocker (doxazosin) in protecting against stroke, and to the ACE inhibitor (lisinopril) in protecting against stroke in blacks.
Davis said that the benefits of the diuretic drug were experienced by men and women, people with diabetes and those without, people with and without normal renal function, as well as people with and without metabolic syndrome.
"Since the initial publication of the ALLHAT findings more than five years ago, many questions and some criticisms have been raised," said Dr. Jackson T. Wright, lead author and professor at Case Western Reserve University.
"This paper reviews the initial findings in light of more detailed analyses of the ALLHAT data and data from more recent clinical trials. All confirm the initial ALLHAT findings that diuretics (in appropriate doses) remain unsurpassed in reducing blood pressure and preventing major complications of hypertension," Wright added.
The research team looked at a meta-analysis of the ALLHAT study and 28 other high blood pressure clinical studies in which patient data were combined and results compared, as well as new clinical trials including the Avoiding Cardiovascular Events Through Combination Therapy in Patients Living with Systolic Hypertension (ACCOMPLISH).
Davis said the large meta-analysis of antihypertensive treatment trials involving 162,341 patients confirmed initial findings of the ALLHAT study in regard to the benefits of the diuretic drug. The study was conducted by the Blood Pressure Lowering Treatment Trialists' Collaboration and results were published in The Lancet in 2003.
"Evidence from subsequent analyses of ALLHAT and other clinical outcome trials confirm that neither alpha blockers, angiotensin-converting enzyme inhibitors, nor calcium channel blockers surpass thiazide-type diuretics (at appropriate dosage) as initial therapy for reduction of cardiovascular or renal risk," the authors wrote.
The study titled 'ALLHAT Findings Revisited in the Context of Subsequent Analyses, Other Trials and Meta-analyses' has been published in the Archives of Internal Medicine.