Epoetin Alfa Resistance: Valuation of a Management Algorithm
Marketed in the last decade, epoetin alfa (Eprex, Janssen-Ortho Inc., Toronto, Ontario) has improved the quality of life of patients with anemia associated with chronic renal disease. This anemia is primarily the result of inadequate erythropoietin production and other factors such as iron deficiency. Anemia causes cardiac ischemia and left ventricular hypertrophy, both of which predispose patients with chronic renal disease to cardiac morbidity. Most patients on chronic dialysis require administration of epoetin alfa for the optimal management and prevention of anemia.
Most patients with chronic renal disease respond to a subcutaneous epoetin alfa dose of 300 IU kg-1 week-1 (or 450 IU kg-1 week-1 IV) within 4 to 6 months. However, the epoetin alfa doses required to achieve a target hemoglobin of 110 to 120 g/L vary considerably. Patients who require large doses of epoetin alfa to achieve and maintain the target hemoglobin or who do not achieve that target despite large doses are usually considered epoetin alfa-resistant or hyporesponsive. Viagra Super Active
The Kidney Disease Outcomes Quality Initiative (KDOQI) guidelines define an inadequate response to epoetin alfa as the inability to achieve the target hemoglobin or hematocrit in the presence of adequate iron stores within 4 to 6 months of the initiation of epoetin alfa therapy (450 IU kg-1 week-1 IV or 300 IU kg-1 week-1 SC). A more dynamic definition classifies as poor responders those patients whose hemoglobin concentration does not increase more than 10 g L-1 month-1, despite epoetin alfa doses of more than 200 IU kg-1 week-1.
The economic and clinical consequences of untreated epoetin alfa resistance include escalating epoetin alfa doses and the associated costs. Failure to deal with the underlying and potentially correctable causes of epoetin alfa resistance robs patients of the health benefits of maintaining their target hemoglobin and wastes health care dollars.
The identified causes of epoetin alfa resistance include medical conditions and deficiencies commonly seen in patients with chronic dialysis such as iron deficiency, blood loss, underdialysis, vitamin B12 and folic acid deficiency, infection, inflammation, aluminum toxicity, osteitis fibrosa cystica, and epoetin alfa noncompliance. Other possible causes of epoetin alfa resistance include hemoglobinopathies, multiple myeloma, malnutrition, hemolysis, and pure red cell aplasia.
Before the project described in this paper, a physician, pharmacist, and nurse assessed anemia monthly in patients with chronic dialysis seen in the hemodialysis unit at St Paul’s Hospital, Saskatoon, Saskatchewan, and adjusted epoetin alfa doses according to a protocol. However, epoetin alfa resistance was not systematically identified and managed. canadian cialis online
The objective of the project described here was to develop and validate an algorithm to guide the investigation and management of suspected epoetin alfa resistance in patients on chronic dialysis. This report describes the experience of staff at the Renal Risk Reduction Centre at St Paul’s Hospital with the algorithm from October 2000 to March 2001.