Participants receiving darbepoetin alpha also received periodic subcutaneous injections of the drug with the aim of increasing their levels of hemoglobin a protein in red blood cells that carries oxygen to a level of 13 grams per deciliter. If someone in the control group dropped to a dangerous hemoglobin level below 9 g/dl, he or she received "rescue therapy" with darbepoetin until the hemoglobin level returned to a level above 9 g/dl.
In analyzing the results, the researchers divided the participants into two groups: those whose hemoglobin levels promptly increased in response to early doses of darbepoetin alpha, and those whose bodies responded less strongly, with hemoglobin level staying low.
The participants who had poor initial responses to the drug had a higher rate of death, heart attack, stroke or heart failure, the researchers found.
The study cannot show whether those people had higher risk for those outcomes because they were in poorer health to begin with, or because of some action of the drug, the researchers stated.
However, it does raise the question of whether treatment for anemia should be customized according to a patient's response to the drug, Dr. Toto said.
"Our studies suggest that we might be able to use the initial dose response to identify high-risk groups in future studies," he said.
For instance, if a person's hemoglobin level doesn't improve within one or two months of anti-anemia treatment, it may be better to stop the drug and seek alternative treatment. A state of mild anemia might pose less cardiovascular risk in such a case than continuing or escalating the dose in an attempt to reach a normal hemoglobin level, Dr. Toto said. Conversely, for patients who respond quickly to the drug, treating them until they reach the normal goal range recommended by the Food an
|Contact: Aline McKenzie|
UT Southwestern Medical Center