FRIDAY, Dec. 9, 2005 (HealthDay News) -- For years, experts have claimed that relatively expensive blood pressure drugs such as ACE inhibitors offer special protection against kidney disease.
But a new British study suggests that's not the case -- that the drugs' benefit to kidneys comes only from their ability to reduce blood pressure. They also believe that cheaper antihypertensive medications might work just as well.
"In patients with high blood pressure who are at risk of progressive kidney disease -- particularly diabetics -- it doesn't matter which blood pressure drug you use, provided you get good control of the blood pressure," concluded lead researcher Dr. Raymond MacAllister, a senior lecturer at the Centre for Clinical Pharmacology at University College, in London.
Currently, guidelines call for the use of two types of drugs -- angiotensin-converting-enzyme (ACE) inhibitors and angiotensin-II receptor blockers (ARB) -- as first-line medications for lowering blood pressure in patients with kidney disease. It's been assumed that these drugs have specific protective effects for the kidneys, beyond their ability to lower blood pressure.
But MacAllister's group questions that assumption in a study published in the Dec. 10 issue of The Lancet.
The British team reviewed the published evidence supporting the use of ACE inhibitors and ARBs as first-line treatment for patients with kidney disease. They pored over 127 trials that investigated the effect of different classes of blood pressure-lowering drugs on the progression of kidney disease.
ACE inhibitors and ARBs were no better than other blood pressure-lowering drugs in preventing diabetic kidney disease, they found. It was also unclear if these two drug classes were more effective in patients with nondiabetic kidney disease.
Many other relevant studies never reached publication, MacAllister noted. "It is not possible to be certain, but this may have happened because their results conflict with the accepted wisdom. This is one explanation why the current dogma has come to be so widely accepted."
National and international committees that formulate guidelines for kidney disease need to take all the evidence into account rather than concentrating on selective evidence, MacAllister said. "They seem to only have referred to data that supports the conventional view. As a result, they have drawn conclusions and issued policy that is inconsistent with much of the available world data and have promoted the use of high-cost drugs over equally effective cheaper options," he said.
MacAllister noted that older, cheaper types of antihypertensive drugs, which are as just effective as the ACE-inhibitors and ARBs, would be a more cost-effective option for health-care systems. "It is not a message that Big Pharma wants to hear, however," he said.
Since all the drugs seem to have the same protective effect, there is no need for patients to change their current treatments, MacAllister advised. "However, ACE-inhibitors and ARBs are up to 20 times more expensive than other antihypertensive drugs. I know which type I would be taking if I were paying out of my own pocket," he said.
The key to preventing kidney disease is good blood pressure control, MacAllister said.
One expert agreed that doctors may need to question accepted dogma when it comes to the treatment of kidney disease.
The British study is "a very interesting and well-done paper that counters the conventional wisdom that there is something about ACE inhibitors and ARBs, beyond their blood pressure-lowering effect, that is renoprotective, especially in diabetics," said Dr. Harlan M. Krumholz, a professor of cardiology at Yale University Medical School.
"When you review the preponderance of evidence, it seems that their effect is mediated by blood pressure lowering, and that diabetics do not have any special benefit," Krumholz added.
The study suggests that smaller studies may be more susceptible to bias, Krumholz noted. "That may not be true in the future with the need to register trials, but may have affected what was published in the past," he said.
More information
For more on high blood pressure and kidney disease, head to the National Institute of Diabetes and Digestive and Kidney Diseases.
