Simple drug combination reduces risk by one-fifth -- even in patients with normal blood pressure

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Vlado Perkovic, MBBS, PhD

For patients with type two diabetes, a combination of two blood-pressure-lowering drugs reduces the risk of kidney disease by about 20 percent—even in patients who don't have high blood pressure, reports a study in the April 2009 issue of the Journal of the American Society of Nephrology (JASN). The analysis was based on the randomized ADVANCE study, which included 11,140 patients with type two diabetes. One group received a combination of two antihypertensive (blood pressure-lowering) drugs: the angiotensin-converting enzyme (ACE) inhibitor perindopril and the diuretic drug indapamide. The other group received inactive placebos.

Although most of the patients had hypertension, 20 percent had normal blood pressure: less than 130/80 millimeters of mercury (mm Hg).

"This research demonstrated that lowering blood pressure with an ACE inhibitor/diuretic combination prevents kidney complications, and even cause some early manifestations of kidney disease in people with diabetes regardless of whether their blood pressure is normal or elevated," comments Vlado Perkovic, MBBS, PhD, of The George Institute for International Health in Sydney, Australia, one of the study authors.

The two groups were followed up to compare their rates of kidney disease events, ranging from a drop in kidney function to kidney failure. An average of four years later, the rate of kidney disease was significantly lower for patients receiving the combination drug therapy—21 percent lower than in the placebo group. In some patients who previously had early signs of diabetes-related kidney disease, kidney function returned to normal during treatment with blood pressure-lowering drugs.

The drug combination reduced kidney disease events even in patients who did not initially have high blood pressure. The lower the blood pressure level, the lower the risk of kidney disease—even at blood pressures below the currently accepted normal level (130/80 mm Hg).

Although more research is needed, these results raise the possibility that patients with type two diabetes should be considered for antihypertensive treatment even if they have normal blood pressure.

The study has some important limitations, including the fact that it was a post-hoc analysis of a previous clinical trial. "Most of the findings related to early manifestations of kidney disease (albuminuria) and the study was not large enough to assess the impact of the intervention directly on the risk of kidney failure," Perkovic adds. "We could not separate out the impact of the blood pressure lowering combination used, or prove whether it had any effects beyond its blood pressure-lowering effects."

Source: American Society of Nephrology