Combining blood pressure–lowering drugs can cause serious side effects in patients with type 2 diabetes and moderately decreased kidney function, according to a late breaking poster, Combined Angiotensin Inhibition for Treatment of Diabetic Nephropathy: VA Nephron D (Abstract 5780), presented at the American Society of Nephrology’s Kidney Week 2013.

Linda Fried, MD, FASN from VA Pittsburgh Healthcare System and her colleagues examined the effects of combination therapy with two types of blood pressure-lowering drugs: angiotensin converting enzyme (ACE) inhibitors and angiotensin receptor blockers (ARB). The combination is known to decrease protein excretion in the urine, which is a marker of kidney dysfunction, but its safety and impact on progression of kidney disease is uncertain.

In this study, 1,148 patients with type 2 diabetes who had moderately decreased kidney function were treated with the ARB losartan and then randomized to receive the ACE inhibitor lisinopril or placebo.

(Research shows association between ACE inhibitors, acute kidney injury)

After a midpoint follow-up of 2.2 years, significant kidney function decline occurred in 152 patients in the monotherapy arm and 132 in the combination arm. There was no benefit on mortality or cardiovascular events.

“The study was stopped early by the data monitoring committee as they concluded that the risks of combination therapy outweighed a small possible benefit on progression of kidney disease, though not statistically significant,” said Dr. Fried. The main risks were a 1.7-fold higher risk of acute worsening of kidney function and a 2-fold higher risk of elevated potassium levels in the blood. Individuals on combination therapy also had a higher rate of hospital admissions.

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