SATURDAY, Oct. 31 (HealthDay News) -- A drug designed to fight anemia appears to double the risk of stroke in patients with diabetes and kidney disease without substantially improving their quality of life, a new study finds.

Darbepoetin alfa, marketed as Aranesp and known as an erythropoiesis-stimulating agent (ESA), is often prescribed for diabetic patients with chronic kidney disease and mild anemia.

"The benefits we assumed we would have by treating anemia were less striking and the risks were more striking," said lead researcher Dr. Marc A. Pfeffer, a professor of medicine in the cardiovascular division of Brigham and Women's Hospital in Boston.

"This provides new data for doctors and patients to make their own risk-benefit assessment," he said. "There was a perception that treating anemia would make people feel so much better that we'll take risks, but the benefit in quality of life was not as great as we thought, and there was a clear doubling of your risk for a stroke."

The report was published in the Oct. 30 online edition of the New England Journal of Medicine to coincide with its scheduled presentation at the annual meeting of the American Society of Nephrology in San Diego.

For the study, Pfeffer's team randomly assigned more than 4,000 patients with diabetes, chronic kidney disease and anemia to receive Aranesp or placebo. During the study, 632 patients receiving Aranesp died or suffered a cardiovascular event, compared to 602 of the patients receiving placebo.

As well, 101 patients taking Aranesp had a fatal or non-fatal stroke compared with 53 of the placebo patients, the researchers found. In addition, patients taking Aranesp reported only a modest improvement in their fatigue, the researchers noted.

In earlier studies, Aranesp and a similar drug, epoetin alfa, marketed as Procrit or Epogen, were linked to increased risk of death in cancer and stroke patients.

Pfeffer believes that people with more severe kidney disease, such as those on dialysis, might still find Aranesp beneficial and the risk acceptable.

"People on dialysis generally feel even worse and generally have even more severe anemia, and this class of therapy has been very helpful to them," he said.

Because the drug was beneficial to these patients, doctors assumed it would help less severely anemic patients, Pfeffer said.

"But this use of ESAs exceeded the data," he said. "Now we have the data, and we will revisit how the drug is used now."

Dr. Phillip Marsden, a professor of medicine at the University of Toronto and author of an accompanying journal editorial, said these findings mean that doctors and patients will have to discuss whether or not to start the medication.

"For most of these patients, the modest improvement in quality of life will not be enough to subject themselves to the increased risk of stroke and death," he said.

ESAs have been used for two decades, Marsden noted. "It is a bit shocking that it took us 20 years to address whether or not these drugs were safe -- and now we know more."

Dr. Ajay Singh, clinical chief of the renal division and director of dialysis at Brigham and Women's Hospital, said this "landmark study" raises the fundamental question of whether epoetin or darbepoetin should routinely be used in treating anemia of chronic kidney disease.

"Earlier studies raised the specter of increased risk with ESA treatment. This study definitively confirms that there is meaningful risk with routine use of ESAs," said Singh, also an associate professor of medicine at Harvard Medical School.

"In my own practice, I will be cautious in using ESAs for most patients with chronic kidney disease, balancing risk with benefits and reserving treatment largely for patients who need frequent blood transfusions or who are candidates for a kidney transplant," he said.

More information

For more information on ESAs, visit the U.S. Food and Drug Administration.

SOURCES: Marc A. Pfeffer, M.D., Ph.D., professor of medicine, cardiovascular division, Brigham and Women's Hospital, Boston; Phillip Marsden, M.D., professor of medicine, University of Toronto, Canada; Ajay Singh, M.D., clinical chief, renal division, director, dialysis, Brigham and Women's Hospital, and associate professor, medicine, Harvard Medical School, Boston; Oct. 30, 2009, New England Journal of Medicine, online

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