OBJECTIVES: Epoetin alfa (EPO) and darbepoetin alfa (DARB) are approved for the treatment of anemia in patients with chronic kidney disease (CKD) not on dialysis; however, little is known about their dosing patterns in the elderly population. The objective of this analysis was to evaluate the frequency of administration, dosage, and associated drug cost of EPO and DARB in patients =65 years of age with CKD not on dialysis. METHODS: A retrospective analysis was conducted using medical claims from approximately 30 health plans during the period of 07/2002 through 02/2004. To be included in the analysis, patients were required to be =65 years old, have =2 EPO or DARB claims, have a CKD diagnosis and not be on dialysis, have no prior cancer diagnosis, and be newly treated with either agent. 2003 wholesale acquisition costs (WAC) were used to calculate drug costs. RESULTS: 149 EPO and 35 DARB patients met the inclusion criteria. More males were in the EPO group (54.4% vs. 34.3%, p=0.03). Age was similar between the groups (mean years; EPO 74.4±5.3; DARB 74.4±5.6, p=0.96), as was average therapy duration (days; EPO 86.7±86.5; DARB 81.2±78.8, p=0.73). Weekly and extended (=Q2W) dosing regimens were found in both groups (EPO – QW: 40.3%, Q2W: 40.3%, =Q3W: 19.5%; DARB – QW: 14.3%, Q2W: 54.3%, =Q3W: 31.4%). The average time interval between drug administrations was 13.0±6.9 days for the EPO group and 15.6±5.4 days for the DARB group. The average weighted weekly dose was 11,121±10,773 Units for EPO and 46.0±29.9 mcg for DARB, corresponding to an average weekly drug cost of $124 for EPO and $184 for DARB. CONCLUSION: Extended dosing (=Q2W) of EPO and DARB was identified in a majority of elderly anemic CKD patients not on dialysis, with lower drug acquisition costs observed in the EPO group compared to the DARB group.