Amy Mottl, MD
Director, UNC Anemia Clinic
Chronic kidney disease can result in multiple problems including anemia. The kidneys make a hormone called erythropoietin (EPO) which is important to the production of red blood cells. As the kidney loses function, it is less able to make this hormone, and patients often become anemic. Symptoms of anemia include shortness of breath and fatigue (feeling tired). In some patients, anemia can become severe, resulting in chest pain and an increased risk of heart disease.
Until the late 1980s, when synthetic EPO (epogen, procrit, aranesp) came to market, kidney patients often were dependent on blood transfusions to treat their anemia. This put them at risk of infectious complications such as hepatitis and HIV. EPO medications are a much better solution for the treatment of anemia due to kidney disease than transfusion. Still, there has been much debate over what the target blood count should be for anemia patients. It seems logical that a higher blood count would be better than a lower blood count since blood carries oxygen which is important to the functioning of the body’s tissues. Many observational studies have indicated this to be true, with patients having higher blood counts feeling better, more energetic and having less heart trouble. Several small clinical trials also seemed to support this idea that a higher blood count is better. As a result, the National Kidney Foundation (NKF) recently changed its recommendations for target hemoglobin (blood count) levels to be 11-13mg/dl rather than the previous recommendation of 10-12mg/dl which is what the Food and Drug Administration (FDA) had originally approved. You can read the NKF's hemoglobin guidelines here.
In the past, observational studies and small trials have occasionally given misleading information. The November 16th issue of The New England Journal of Medicine published two large prospective randomized trials both demonstrating that targeting blood counts to the ‘normal’ levels do not reduce the risk of heart disease or stroke. Each of these trials randomly assigned half of the patients to a ‘normal’ blood count and the other half to a lower than normal blood count. One of these two trials found that the group with a normal blood count (hemoglobin 12-12.5mg/dl) had a higher risk of heart disease and stroke than those with a lower blood count (hemoglobin 11-11.5). Over the three year trial, 17.5% of those with a higher blood count had a cardiovascular outcome (death, heart attack, stroke, hospitalization for heart failure) versus 13.5% of those with a lower blood count. ‘Quality of life’ measured with two different questionnaires were similar. The other study which was smaller, showed no difference in cardiovascular outcomes but did find an improved ‘quality of life’ in those with a higher blood count.
These recent findings are unexpected, as these two trials were initially begun with the thought that a higher blood count would lower the risk of heart disease. There has been an upheaval amongst patients, medical providers and insurers over this new information. Caring for patients is first and foremost in the minds of all, however, EPO medications are also very expensive. The vast majority of EPO is paid for by Medicare, funded by U.S. taxpayers. It has been suggested that patients were receiving higher than necessary doses of EPO for payment purposes. Although this may be true in rare cases of less ethical providers, it’s certainly does not explain the reason most providers may have been trying to increase their patients’ blood counts. Until the release of these recent findings in the New England Journal of Medicine, it was felt by most medical providers that a higher blood count would make patients feel better and be at LESS risk of heart disease or stroke.
The National Kidney Foundation has established a committee to review these studies and come out with new guidelines for the treatment of anemia of chronic kidney disease. The U.S. Congress has also met regarding this issue to determine whether they should pass laws for the payment of EPO drugs by Medicare and Medicaid. You can read about the congressional meeting here.
It’s natural for patients receiving EPO medications to have questions about what this means for their medical care. It’s important to put these findings into perspective, however. EPO medicines have greatly improved the health and quality of life of patients with anemia of chronic kidney disease. The risk of having severe anemia (hemoglobin less than 10mg/dl) is greater than being treated with EPO to maintain a slightly lower than normal blood count (hemoglobin 10-12mg/dl). The reasons for an increased risk of cardiovascular disease with a higher blood count are not known, although the patients in this group also received higher doses of EPO. More studies are being planned to clarify the relationship between a higher blood count and possible increased risk of heart disease or stroke.
Anemia Clinic Letter to Patients
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