A class of drug commonly used to treat anemia in patients with kidney disease appears to confer no benefit and subjects patients to several risks. This conclusion comes from an analysis of 27 previous studies of the drugs, called erythropoesis-stimulating agents (ESAs).

The reason for giving ESAs to patients with kidney disease is that they should improve a patient's overall quality of life. But the recent meta-analysis showed no such improvement. It did however show an increased risk of stroke and thrombosis (arterial blood clot).

Anemia (low red blood cell count) is a common side effect of kidney disease. ESAs cause the body to produce more red blood cells. Because they do not directly affect kidney disease, the reason for giving ESAs to patients with kidney disease is that they should improve a patient's overall quality of life. But the recent meta-analysis showed no such improvement. It did however show an increased risk of stroke and thrombosis (arterial blood clot).

Patients given sufficient ESA to normalize their red blood cell count had a 51% increased risk of stroke and a 33% increased risk of thrombosis. Increased risk of death (9%) and serious cardiovascular events such as heart attack (15%) were also found, but these increases were too low to be statistically significant.

Because of safety concerns, the FDA earlier this year required that ESAs contain a "black box warning" and also required that doctors prescribing ESAs to their patients inform them of the drug's risks and obtain signatures authorizing their use.

With increased risks and no obvious benefit, there is no reason that ESAs should be generally prescribed to patients with kidney disease. But there are reasons why individual patients might benefit from them.

Almost all the studies looked at were of elderly patients. Though the 27 studies included over 10,000 patients, few were under the age of 50 and many were over 60. Younger patients are the ones most likely to show a quality of life improvement from anemia treatment, as it may allow them to be more active. Yet the fact that ESAs currently cost Medicare $2 billion dollars a year indicates that they are often prescribed to the elderly.

Kidney disease patients who are undergoing dialysis generally have more severe anemia than other patients with kidney disease. The study authors suggest that they are a group that might show some benefit from ESAs.

Most studies have used sufficient ESA to boost patients' red cell count up to the normal range. It's possible that more modest treatment might not be so dangerous. Many patients with kidney disease have anemia severe enough to require blood transfusions. ESA treatment seeking to boost red cell count slightly above the level where blood transfusions are needed may be less risky than treatment at the dose currently used.

More studies are required to see whether ESA treatment of younger patients or low-level ESA treatment to avoid the need for blood transfusions would be safe and effective. But right now, there appears to be no rationale for ESA use as a standard treatment for patients with kidney disease.

An article detailing the study was first published online May 3, 2010 by Annals of Internal Medicine and is freely available. The article will also appear in the July 6 issue of the Journal.