No Marker IDs Nonresponders to IV Iron
The finding comes from the Dialysis Patients' Response to IV Iron with Elevated Ferritin (DRIVE) study, a six-week randomized controlled trial. The study examined the ability of anemic hemodialysis patients with elevated serum ferritin, low TSAT, and sufficient epoetin doses to mount adequate hemoglobin response to IV iron, defined as a rise of 2 g/dL or greater at any point during the study.
Contrary to expectations, investigators found that a higher baseline reticulocyte hemoglobin content (CHr) was associated with a greater likelihood of responding to IV ferric gluconate. Even the patients in the lowest CHr quartile had a 20% response rate, indicating that a low CHr is not an effective predictor of iron responsiveness in this patient population.
“These findings are very important because 20% of the dialysis population has a high ferritin and a low TSAT, and generally we struggle to treat their anemia,” said investigator
The study had 129 patients, of whom 65 received no iron and 64 received ferric gluconate. The mean age was approximately 59 years and about 50% were African American. The two groups were similar in demographics, history of kidney disease, and baseline epoetin dose and biochemical parameters. All the patients received a 25% increase in epoetin dose during the six weeks. The IV iron group received 1 gram sodium ferric gluconate complex (SFGC).
SFGC was more effective than no iron in improving hemoglobin levels overall and in helping to maintain CHr levels. Hemoglobin responses occurred in 46.9% of the SFGC group and 29.2% in the no-iron group. Among the patients in the IV iron group, those with CHr levels of 31.2 pg/cell were 5.3 times more likely to have a hemoglobin response than patients with lower CHr levels. Having CHr levels less than 31.2 pg/cell did not rule out response in the SFGC group.
Although patients with C-reactive protein (CRP) levels greater than 14.1 mg/L were less likely to respond than those with lower levels, the differences were not sufficient to recommend using this test clinically to decide who should receive iron, according to the investigators. TSAT, serum ferritin, soluble transferrin receptor, and change in epoetin dose had no effect on likelihood of response. Within the no-iron group, patients' likelihood of response was driven only by the magnitude of increase in epoetin dose.
“This study adds new information that may be of relevance to the guidelines process,” Dr. Singh said, adding that the Kidney Disease Outcome Quality Initiative (KDOQI) guidelines for CKD anemia management that came out in May 2006 noted a lack of efficacy data for IV iron when ferritin levels are above 500 ng/mL. “This study demonstrates efficacy in anemia pa-tients with high ferritin.”
The DRIVE study was designed by Daniel Coyne, MD, Wadi Suki, MD, and Dr. Singh.