Millions of Americans take an ACE inhibitor to help curb their high blood pressure -- in fact, these drugs are the most widely used antihypertensives in America.
However, a new international study of nearly 5 million patients is casting doubt on the notion that the drugs are as effective as another class of blood pressure medicines.
Common ACE inhibitors include drugs such as benazepril, captopril, enalapril, fosinopril and lisinopril, among others.
The new study should "help guide physicians in their clinical decision-making," said study author Dr. George Hripcsak. He's chair of biomedical informatics at Columbia University's College of Physicians and Surgeons, in New York City.
American College of Cardiology and American Heart Association guidelines recommend starting blood pressure treatment with any drug from five different classes of medications. Those classes include: thiazide diuretics; ACE inhibitors; angiotensin II receptor blockers (ARBs); dihydropyridine calcium channel blockers and non-dihydropyridine calcium channel blockers.
To find out how often these medicines are prescribed, Hripcsak's team tracked data on nearly 5 million patients across four countries -- Germany, Japan, South Korea and the United States.
All of the patients began treatment for high blood pressure by using a single drug.
In nearly half (48 percent) of cases, ACE inhibitors were the first drug prescribed, compared with 17 percent of patients who were first prescribed thiazide diuretics, the team found.
But the study suggests that ACE inhibitors might not always be the best choice.
Patients who were prescribed thiazide diuretics ended up having 15 percent fewer heart attacks, strokes and hospitalizations for heart failure, as well as lower rates of 19 side effects, compared to those who had been prescribed ACE inhibitors.
Crunching the numbers, the Columbia team calculated that about 3,100 major cardiovascular events among the patients who first took ACE inhibitors could have been prevented if they'd first been treated with a thiazide diuretic.
They reported their findings Oct. 24 in The Lancet journal.
The researchers also found that another class of blood pressure meds, non-dihydropyridine calcium channel blockers, were less effective than all of the other first-line classes of blood pressure drugs.
Right now, there's a real lack of research aimed at helping doctors choose which drug class a patient should start on, Hripcsak believes.
He noted that the current literature has data from randomized, controlled clinical trials that included a total of just 31,000 patients, and none of those patients were just beginning treatment for high blood pressure.
"Randomized clinical trials demonstrate a drug's effectiveness and safety in a highly defined patient population," Hripcsak explained in a university news release. "But they're not good at making comparisons among multiple drug classes in a diverse group of patients that you would encounter in the real world."
With the new study, Hripcsak believes that "we have found a way to fill in the gaps left by randomized, controlled trials.
Two cardiologists who weren't involved in the new study took different stances on the results -- suggesting that debate on this topic is far from over.
Dr. Satjit Bhusri said the study "is statistically very powerful and can have profound changes in medical practice." But he added that decisions around which anti-hypertensive drug to choose should still be made on a case-by-case basis.
"I would suggest that the choice of first-line blood pressure therapy be specific to the patient, especially in those with heart disease or at an elevated risk of heart disease," Bhusri advised. But, for patients "treated for high blood pressure without an elevated cardiac risk, thiazide medication should be the first-line [choice]," he said.
However, cardiologist Dr. Benjamin Hirsh took issue with the Columbia study's methodology.
The researchers' conclusion that "use of thiazide diuretics over ACE inhibitors causes '15 percent fewer cardiovascular effects' is a conclusion that is highly subject to bias," he noted.
"ACE Inhibitors are used to treat patients with higher cardiovascular risk, such as those with advanced heart failure and kidney disease," Hirsh explained."So, these patients are at higher risk for heart disease in general."
According to Hirsh, it stands to reason that patients on ACE inhibitors would have worse outcomes than those on thiazide diuretics, because they were sicker to begin with.
And he noted that "thiazide diuretics also must be used carefully with other drugs." Those include newer diabetes medications such as Jardiance, because the concurrent use of a thiazide diuretic might trigger too-low blood pressure, Hirsh explained.
The U.S. National Heart, Lung, and Blood Institute has more on high blood pressure.
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