Inexpensive diuretics best at helping hypertension
OTTAWA, ON, Dec. 17 /CNW/ - Inexpensive traditional diuretics "water
pills" are more effective at treating high blood pressure and some forms of
heart disease than some of the newer drugs on the market. This key finding
comes out of the largest North American hypertension clinical trial ever held.
The Antihypertensive and Lipid-Lowering Treatment to Prevent Heart Attack
Trial (ALLHAT) ran between February 1994 and March 2002, and studied 42,418
participants in 623 general medical and specialty clinics across Canada, the
United States, the U.S. Virgin Islands and Puerto Rico. Sponsored by the
National Heart, Lung, and Blood Institute (NHLBI - part of the U.S.'s National
Institutes of Health), the randomized double-blind trial had two components:
The first compared a diuretic with newer antihypertensive drugs to begin blood
pressure-lowering treatment. The second focused on cholesterol, comparing the
effects of a statin drug with 'usual care'.
"The findings will have a significant impact, not only on the way we
treat patients in the future, but on the cost of that treatment" said
Dr. Frans Leenen, Director of Hypertension Research at the University of
Ottawa Heart Institute and the lead Canadian investigator for the trial.
"Approximately one quarter of all Canadians struggle with hypertension. If
more patients are treated with the less expensive diuretics and this also
lowers the cost of treatment, then both patients and the health care system
benefit," Leenen said.
"Patients being treated for hypertension or high cholesterol are
encouraged to increase their physical fitness, eat less saturated fat, and
lose weight if appropriate, and limit their consumption of salt," said
Dr. Anthony Graham, Heart and Stroke Foundation Spokesperson and Cardiologist.
"If these changes do not lower blood pressure or cholesterol enough, the next
step is usually to add drug therapy to the treatment."
Those participating in ALLHAT had high blood pressure (140/90 mm Hg or
higher) and at least one other risk factor for heart disease. For the first
time, large numbers (47 per cent) of the participants were women. Forty-seven
per cent were non-Hispanic white, 32 per cent were African-American, 16 per
cent were Hispanic, and 36 per cent had Type 2 Diabetes.
Participants underwent medical checkups every three months for the first
year after entry into the study and every 4 months after for an average of 4.9
years. They were randomly given one of four drugs: a diuretic
(chlorthalidone); a calcium channel blocker (amlodipine); an angiotensin
converting enzyme (ACE) inhibitor (lisinopril); or an alpha-adrenergic blocker
(doxazosin). They received additional antihypertensive drugs if necessary to
manage their blood pressure.
In March 2000, those study participants receiving the alpha-adrenergic
blocker were taken off their protocol since it was found they had 25 per cent
more cardiovascular events, and were twice as likely as users of the diuretic
to be hospitalized for heart failure.
As for the other drugs, the findings showed that, compared with a
diuretic, the calcium channel blocker resulted in
- an average of 1mm Hg higher systolic blood pressure;
- a 38 per cent greater risk of developing heart failure;
- all other outcomes (eg. Heart attack and stroke) show the same outcome
In contrast comparing the diuretic with the ACE inhibitor, the trial
found the ACE inhibitor resulted in
- an average of about 2 mm Hg higher systolic blood pressure and 4 mm Hg
higher in African Americans;
- a 15 per cent greater risk of stroke for all participants but 40 per
cent greater risk of stroke for African Americans;
- a 19 per cent greater risk of developing heart failure;
- an 11 per cent greater risk of being hospitalized or treated for angina
(chest pain); and
- a 10 per cent greater risk of having to undergo a coronary
revascularization (such as coronary artery bypass surgery).
"So, one of the key things we learned through ALLHAT is that we should
begin a patient's treatment with diuretics" said Leenen, "and then, based on
their response, evaluate whether additional treatment is required. It's
important to stress, however, that patients who are taking ACE inhibitors or
calcium blockers now, should not stop taking their medication. Instead they
should meet with their doctor to discuss the use of a diuretic in their
treatment. Quite often both a diuretic and a second medication is required."
The separate ALLHAT cholesterol study was the first to be done
exclusively in patients with high blood pressure. The study involved 10,355 of
the trial's participants, all with moderately elevated blood cholesterol but
who were not judged to need a cholesterol-lowering medication. All
participants also had at least one risk factor for heart disease and about
half of the study's participants were women. Thirty-eight per cent were
African-American, 23 per cent were Hispanic, 35 per cent had Type 2 Diabetes
and 14 per cent had heart disease at the start of the study. They were
followed for 4.8 years.
The results indicated a noticeable drop in cholesterol levels in both
groups. Between the 'usual care' group and those taking statins, the
difference in results was too small to show a difference in death rates, with
only a small, insignificant decrease in the statin group's rate of heart
attack and stroke.
The complete ALLHAT findings may be found in the December 18, 2002
edition of The Journal of the American Medical Association (JAMA).
Dr. Frans Leenen is a world-renowned Hypertension specialist who is a
career investigator of the Heart and Stroke Foundation of Ontario, with
research supported by the Canada Institute of Health Research and Heart and
Stroke Foundation of Ontario.
The University of Ottawa Heart Institute is a bilingual academic health
care institution dedicated to the promotion of cardiovascular health. It is an
international centre of excellence for the diagnosis, treatment,
rehabilitation from and prevention of heart disease through patient care,
research and education.
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For further information: Liane Craig, Chief Communications Officer,
(613) 761-4850, lcraig@ottawaheart.ca |
