NN&I - August 2010

Clinical 18 Nephrology News & Issues August 2010Subscribe to our free eNewsletter at www.nephronline.com Hematide may cause heart problems in CKD patientsResearchers find location of gene linked to hereditary kidney diseasePopular heart drug may be unsafe for some kidney patientsDebate arises over blood pressure guidelinesPhase 3 results for Affymax Inc.'s ane-mia drug Hematide released June 21 showed the drug to be as effective as Epogen and Aranesp in raising hemo-globin levels, but also may increase the risk of cardiovascular problems among patients with chronic kidney disease. The findings showed 21.6% of non-dialysis kidney patients taking Hematide had a cardiovascular com-plication, compared with 17.1% of CKD patients taking Aranesp. More Hematide users died from heart-relat -ed problems (8.8%) than those taking Aranesp (6.7%) in the CKD population. The heightened risk for heart prob-lems only appeared in non-dialysis patients. In a separate study of renal patients on dialysis, heart-related com -plications affected 23% of Hematide users and 24% on Epogen (For financial implications, see Business on page 15).Researchers conducting a study of a family with multiple generations affected by kidney disease have identified a pre-viously unknown location for a gene abnormality that causes focal segmental glomerulosclerosis (FSGS). Published in the July 8 issue of the Journal of the American Society of Nephrology, researchers from Duke University Medical Center in Durham, N.C. identified a region in the human genome on chromosome 2p linked to FSGS in a large family with more than 12 affected individuals, said the study's lead researcher Rasheed Gbadegesin, MD, MBBS. The family is from central Europe and the FSGS goes back five generations. The affected family members devel-oped kidney disease at different times and all rapidly progressed to end-stage renal disease before age 30. The study only shows the location of the abnormal gene. "Our ultimate goal is to identify the defective gene in this fam- ily and try to understand how it causes FSGS," Gbadegesin said. "Presently we have narrowed the disease to a region of one million bases, out of over three billion bases present in humans." For dialysis patients, the widely used heart medication digoxin may lead to an increased risk of premature death, according to a study appearing in the June 25 issue of the Journal of the American Society of Nephrology. Researchers monitored more than 120,000 dialysis patients receiving treatment at more than 1,800 clinics across North America for four years. "We were surprised to find that digox-in use increased death risk in dialysis patients, especially in patients on higher doses," said researcher Kevin Chan, MD, MSci, senior director of clinical out-comes research and medical analytics at Fresenius Medical Care North America. He added that although digoxin is a mainstay, proper studies of its effective-ness have never been conducted. The risk of death was 28% high-er for dialysis patients taking digoxin, after adjustment for other factors. The increased risk was greater for those with higher digoxin levels in their blood or with lower serum potassium levels. Recent guidelines from the National Kidney Foundation's Kidney Disease Outcomes Quality Initiative call for lower target blood pressure levels in patients with chronic kidney disease. But there is a chance this recommendation could do more harm than good, according to a special article in the June issue of the Journal of the American Society of Nephrology. "The new low blood pressure goals are not definitively supported by data, would be costly to the health care system, and potentially harmful to patients," said Julia B. Lewis, MD, of Vanderbilt University in Nashville, Tenn., who performed a critical review of the research evidence. Issued this past year, updated national guidelines for CKD patients call for a target blood pressure level of less than 130/80 mm Hg to help preserve kidney function. The recom-mendation was based on observational studies showing "a continuous benefit of reducing blood pressure to lower and lower levels." But since patients in the obser -vational studies were not randomly assigned to different blood pressure goals, the apparent benefit of lower blood pressures could result from other "confounding" factors, Lewis said. "The data supporting the current blood pres-sure guidelines for patients with CKD do not meet the standard of a primary outcome of a randomized trial," Lewis said. The data may simply reflect the fact that patients with less severe kidney disease have lower blood pressure, Lewis said. In studies where patients were randomly assigned to treatments, the benefits of lower blood pres-sure were seen only in a subgroup of patients, or several years after the end of treatment. Compiled by Rebecca Zumoff Clinical_NN&I_0810_3.indd 18 7/15/10 1:58:17 PM