While studies were done in an attempt to determine optimal hemoglobin levels using such drugs in these patients, no trial was conducted comparing the drug with a placebo, until TREAT - Trial to Reduce Cardiovascular Events with Aranesp Therapy.

"From a scientific perspective, TREAT is the most rigorous," Dr. Toto said. "It's a randomized, double-blind, placebo-controlled trial."

From August 2005 until March 2009, researchers from 24 countries gave subjects with chronic kidney disease, type 2 diabetes or anemia either a placebo or darbepoetin alfa. Twenty four subjects were from UT Southwestern.

Cardiac death or events occurred in 31 percent of the darbepoetin alfa group and in 29 percent of the placebo group. Kidney disease death or progression to dialysis occurred in 32 percent of the darbepoetin alfa group and in 31 percent of the placebo group.

Researchers did find a modest decrease in reported fatigue levels and a decrease in the need for blood transfusion in subjects taking darbepoetin alfa.