Dec. 17, 2002 -- When it comes to medications to treat high blood pressure, newer isn't necessarily better. In fact, researchers say that in light of new findings from a landmark study, diuretics should be the top choice for combating high blood pressure.
That is the conclusion reached following a massive clinical trial comparing the effects of newer blood pressure drugs to diuretics, which have been around for a much longer time -- and are much cheaper. Specifically, the diuretic studied -- chlorthalidone -- was substantially better at preventing heart failure and stroke that can occur as a result of high blood pressure.
The main diuretic used today is hydrochlorothiazide, or HCTZ, which has fewer side effects than chlorthalidone, the diuretic used in this study. HCTZ is often combined with other diuretics into one pill.
The results of the study, called ALLHAT (Antihypertensive and Lipid-Lowering Treatment to Prevent Heart Attack Trial), appear in the Dec. 18 issue of The Journal of the American Medical Association.
There are several different classes of new blood pressure drugs. But they had not been compared directly with the older diuretics -- until now. Diuretics lower blood pressure by increasing urinary output and reducing the body's sodium and water volume.
The trial "answers a question that doctors have been asking for years, and that is, which of the available medications are best at preventing complications of blood pressure?" Jackson Wright Jr., MD, PhD, professor of medicine at Case Western Reserve University and one of the trial's research coordinators, tells WebMD.
Wright says the study is convincing because it's the largest trial that's ever looked at problems that can stem from high blood pressure and because the trial has large numbers of women, older people, blacks, and Hispanics. "It clearly confirms the findings of previous studies and extends them."
Drugs are usually only prescribed for high blood pressure if lifestyle changes, including diet and exercise, fail to solve the problem.
The findings could have major implications for the newer drugs and their manufacturers. The new drugs have taken a significant chunk of the high blood pressure drug market.
According to the researchers, diuretics fell from 56% of prescriptions for high blood pressure in 1982 to 27% in 1992, giving way to the newer drugs. They estimate that sticking with diuretics would have saved more than $3 billion. About 24 million Americans take drugs to lower high blood pressure, costing about $15.5 billion annually. To put it more succinctly: Switching from newer drugs to a diuretic would save between $250 and $650 per patient per year, the researchers say.
The blood pressure study included more than 42,000 participants aged 55 and older. They received either the diuretic chlorthalidone or one of the new blood pressure drugs -- Norvasc (a calcium channel blocker) or Prinivil or Zestril (generic name lisinopril -- an ACE inhibitor). The part of the study that looked at Cardura -- an alpha adrenergic blocker -- was stopped in 2000 because of an increase in heart disease and stroke among study participants.
In the study, the researchers were mainly looking for how well each blood pressure drug prevented a heart attack or death from heart disease. In addition, they looked for other complications of high blood pressure -- including stroke and heart failure.
After five years, researchers found that the diuretic was just as good at preventing heart attack or death as the newer drugs. But the medicines had different effects on blood pressure. The diuretic was better at lowering systolic blood pressure -- the top number -- than the newer drugs, but Norvasc was better at lowering diastolic blood pressure -- the bottom number.
For heart failure, people taking Norvasc had a 38% higher risk of developing heart failure and a 35% higher chance of being hospitalized for the condition. Those on the ACE inhibitor had a 15% higher risk of stroke, a 19% higher risk of developing heart failure, and other increased risks compared with people taking a diuretic.
Even though the overall death rate was about the same in all groups, strokes and heart attacks seriously reduce quality of life. "These have major impacts on people's lives," said Barry R. Davis, MD, PhD, professor of biometry at the University of Texas School of Public Health and the lead investigator on ALLHAT.
"The take-home message is that doctors should begin drug treatment for high blood pressure with a diuretic," said Paul Whelton, MD, MSc, senior vice-president for health sciences at Tulane University, and an ALLHAT regional coordinator. "A great majority of patients can tolerate a diuretic, but, for those who can't, then a calcium channel blocker, an ACE inhibitor, or a beta-blocker [also a new medication that was not tested in this study] may be used to start treatment."
The trial also indicates that most patients require more than one drug to control blood pressure, with a diuretic being a key component of any such combination.
If you are currently taking a calcium channel blocker, an ACE inhibitor, or another high blood pressure drug besides a diuretic, you should certainly continue to take your medication, but you should also talk to your doctor about adding a diuretic or switching to one, says Whelton.
ALLHAT Follow-up:Water Pills Help All With Hypertension WebMD Feature, Jan. 2, 2003.
ALLHAT Follow-up:What To Do: Treat, Don't Tolerate High Blood Pressure WebMD Feature, Jan. 14, 2003.
ALLHAT Follow-up:Monitoring Blood Pressure at Home WebMD Feature, Jan. 17, 2003.