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Hypertension & Stroke

From the Current Issue

Should You Be Taking a Diuretic?
Water pills are recommended for most people with high blood pressure, but doctors don’t always prescribe them. Here’s why they should.

Current treatment guidelines state that thiazide diuretics should be used as initial therapy for most patients with hypertension. But in many cases, doctors instead prescribe such drugs as ACE inhibitors, angiotensin II receptor blockers, beta-blockers, or calcium channel blockers. What is the reason for this disparity, and how do you know whether you’re getting the best drug to lower your blood pressure?

What the Guidelines Say

The treatment guidelines, issued by the seventh report of the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure (JNC 7) in 2003, recommend using diuretics—either alone or in combination with other drugs—as first-line therapy in all people with high blood pressure who are otherwise healthy. But in people with other health conditions, a diuretic may not be the first choice. For example, beta-blockers or ACE inhibitors may be the preferred therapy for those with coronary heart disease or kidney disease, respectively, although diuretics may also be used. In addition, diuretics are not appropriate in people who are allergic to them or have experienced serious side effects from them. But most other people with hypertension should receive a diuretic.

The JNC 7 guidelines were based on many studies, including the Antihypertensive and Lipid-Lowering Treatment to Prevent Heart Attack Trial (ALLHAT)—the largest blood pressure drug study ever conducted. As reported in 2002 in the Journal of the American Medical Association (JAMA), the trial compared the traditional recommended therapy, thiazide diuretics, with two newer—but considerably more expensive—medications: a calcium channel blocker and an ACE inhibitor.

Patients in all three groups fared equally well with regard to the occurrence of nonfatal heart attacks or death from coronary heart disease. The thiazide diuretic, however, was superior to the other two drugs in lowering blood pressure and reducing the risk of cardiovascular complications such as stroke and heart failure.

Differing Results

A 2003 study published in The New England Journal of Medicine reached a different conclusion. In it, Australian researchers concluded that initiating therapy with ACE inhibitors instead of diuretics led to fewer cardiovascular complications and deaths from any cause, despite similar reductions in blood pressure.

But there are important differences between this study—the Second Annual Australian National Blood Pressure Study (ANBP2)—and the ALLHAT study. For example, ALLHAT was much larger, with about 24,000 people; ANBP2 had only 6,000 participants. ALLHAT was also better designed in that both subjects and researchers were blinded as to what drugs were being used. In addition, the results of ANBP2 were less consistent: The beneficial effect of ACE inhibitors was present in men but not in women.

Furthermore, a comprehensive meta-analysis of 42 trials recently confirmed the ALLHAT results. The meta-analysis, which was published in JAMA in 2003, combined data on nearly 200,000 people randomized to 7 major treatment strategies, including a placebo. It concluded that low-dose diuretics are the most effective first-line treatment for preventing cardiovascular deaths and illnesses.

The Cost Factor

In addition to being the most effective first-line treatment, diuretics are also the least expensive. The average cost of a prescription for a thiazide diuretic is less than $6, while ACE inhibitors and calcium channel blockers cost five to six times as much.

Despite these findings, many doctors continue to prescribe newer, more expensive drugs in place of diuretics. In fact, in an article published in JAMA in 2004, researchers found that 40% of doctors’ prescriptions fell outside of the JNC 7 recommendations. The researchers theorize that doctors may choose these newer agents based on aggressive marketing campaigns, or on the basis of studies such as ANBP2 that found ACE inhibitors to be more effective than diuretics. But nationwide compliance with the JNC 7 guidelines in prescribing drugs to elderly patients with hypertension would save about $1.2 billion annually.

The Bottom Line

If you’re being treated for high blood pressure and aren’t taking a thiazide diuretic, ask your doctor if you should be. It may be that your doctor has selected a different drug as first-line therapy because you have a condition such as coronary heart disease, diabetes, or kidney disease, or you have had a stroke. But most people need a second drug to control blood pressure adequately. For people who aren’t already taking one, that drug should usually be a thiazide diuretic.

Coexisting health conditions aren’t the only factors that play a part in deciding which drug to prescribe. For example, ALLHAT found that blacks didn’t respond as well as whites to ACE inhibitors. This difference may not be as significant as is commonly believed: A study published in Hypertension in 2004 concluded that whites and blacks respond similarly to common antihypertensive drugs about 90% of the time. The potential for intolerable side effects is also a factor. So you and your doctor may need to experiment with several drugs in order to find the regimen that works best for you.


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Hypertension & Stroke

The Hypertension and Stroke White Paper from the Johns Hopkins White Papers series is an annual, in-depth report written by Johns Hopkins physicians.



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