May 20, 2001 (San Francisco) -- Five million Americans have both type 2 diabetes and high blood pressure, a one-two punch that can seriously damage the kidneys and the heart. Now results from three landmark studies of almost 4,000 diabetic patients suggest that a specific class of blood pressure drugs called angiotensin receptor blockers, or ARBs, can protect kidneys and reduce the need for kidney dialysis or transplant.
Results from all three studies were released Saturday at the annual meeting of the American Society of Hypertension.
Among the findings were the following:
- A 28% reduction in the risk of kidney failure among diabetics with established kidney disease.
- A slowing of the progression of kidney disease.
- A 20% reduction in death.
None of the studies evaluated how well the drugs protect the heart.
Nonetheless, in an impassioned presentation to several thousand high blood pressure experts packed into a hotel ballroom, one of the researchers, Hans-Henrik Parving, MD, DMSc, shouted "I call this victory!" Parving is chief physician at the Steno Diabetes Center in Gentofte, Denmark.
"There is an epidemic of progressive [kidney] disease in the United States, and it is due to type 2 diabetes," says Barry M. Brenner, MD, one of the study authors. "If one lives for 15 years with type 2 diabetes, the number of complications looms very large." Brenner is a professor at Harvard Medical School.
Avapro, a drug marketed by Bristol-Myers Squibb and Sanofi-Sythelabo, was the subject of two linked studies. In the first study, researchers tested the drug's ability to slow the progression of diabetic kidney disease in people who have very early signs of kidney failure. The second study tested Avapro in diabetics with established kidney disease to see if it could prevent progression to kidney failure or death. The drug companies funded the studies.
In both studies, the drug protected the kidneys, says Edmund J. Lewis, MD, who lead the study of more than 1,700 diabetics with established kidney disease. Lewis is a professor at Rush Medical College in Chicago.
The third study evaluated another ARB called Cozaar. Merck is the maker of Cozaar and paid for the study. Brenner, who was the lead investigator of this study, tells WebMD that Cozaar also was effective at slowing kidney disease. This study evaluated more than 1,500 diabetics.
In all three studies, all patients achieved good blood pressure control even if they required additional drugs to do so.
Although the findings for these ARBs are impressive, not everyone is convinced of their superiority. George L. Bakris, MD, a professor at Rush-Presbyterian-St. Luke's Medical Center in Chicago, tells WebMD, "For [kidney] disease it's a slam dunk for the ARBs, but it is not so clear for [heart] disease."
This is a significant issue because diabetes and high blood pressure are both separate risk factors for heart disease and stroke. A patient with both faces double jeopardy. But another class of high blood pressure medications, called angiotensin-converting enzyme inhibitors, or ACE inhibitors, can protect the kidneys and reduce the risk of death from heart disease. Until the release of these new ARB studies, ACE inhibitors have been considered the drug of choice for treating high blood pressure in diabetics. Importantly, none of the studies presented Saturday compared the ARBs against an ACE inhibitor, so it's unknown whether ARBs also can reduce the risk of death from heart disease.
Bakris was an investigator in Brenner's study, and he acknowledges that the study was not designed to evaluate whether Cozaar reduces the risk of heart disease. However, he tells WebMD that Cozaar did reduce "hospitalization for heart failure by 32%."
Parving, who studied nearly 600 people with patients with the earliest stage of kidney disease -- a condition called microalbuminuria -- says that in his study when patients were given Avapro, they had about half the number of heart attacks and strokes as patients who were treated with other blood pressure drugs.
Microalbuminuria means that very small amounts of albumin can be detected in the urine. Brenner says that microalbuminuria happens when "blood vessels in the kidney start leaking protein, which means the vessels are damaged." Parving's study evaluated whether Avapro prevented or slowed the progression of kidney disease from this very early stage. Avapro reduced the risk of progression by 10%, he tells WebMD.
One advantage that the ARBs have over ACE inhibitors is that these drugs are more patient friendly, notes Brenner, who says about one in five patients will stop taking an ACE inhibitor because the drug often causes a dry, hacking cough. There is no cough associated with ARBs, he says.
But the downside of ARBs is cost. Sometimes both an ARB and an ACE-inhibitor fail to control blood pressure without the help of other drugs. Typically patients will take two or more blood pressure medicines, says Bakris. "That means an ACE [inhibitor] or an ARB plus other drugs -- sometimes several other drugs," he says.
ARBs cost about 15-25% more than an ACE inhibitor, especially since generic versions of some ACE inhibitors are available. Since many type 2 diabetics are covered by Medicare, which doesn't pay for prescription drugs, the price of adding an expensive drug to an already long list of medications can create a hardship, says Bakris.