Introduction: Epoetin alfa (EPO) and darbepoetin alfa (DARB) are two erythropoietic agents currently available in the United States for the treatment of anemia in patients with pre-dialysis chronic kidney disease (CKD). The goal of this study was to assess and compare EPO- and DARB-treated CKD patients with respect to dosing patterns, hematologic outcomes, and associated costs.
Materials and methods: In this multicenter, retrospective chart review, 400 charts of anemic predialysis CKD patients (200 treated with EPO and 200 treated with DARB) were sequentially selected from a large self-insured employer health insurance database. The database included both employees and their dependents. Selection criteria included patients newly initiated on EPO or DARB between July 2002 and December 2003 who had at least 24 weeks of dosing and hematologic laboratory data available. Patients with a diagnosis of malignancy or on dialysis were excluded. Dosing frequency was categorized as once weekly (QW), once every 2 weeks (Q2W), every 3 weeks (Q3W), or every 4 weeks (Q4W). Hemoglobin (Hb) levels and dates/doses of EPO and DARB administrations were recorded. Costs were calculated using 2005 wholesale acquisition costs.
Results: Baseline demographics were similar in the EPO and DARB groups with respect to race, sex, renal function, and Hb. Extended dosing (defined as > or =Q2W) was common in both groups. The predominant dosing frequency was Q2W (59.5% of patients) for EPO and Q3W (68.0% of patients) for DARB. Hematologic response (defined as Hb > or = 11 g/dL) was significantly greater in the EPO group at early time points (week 4: EPO 28%, DARB 12%; week 8: EPO 39%, DARB 21%; week 12: EPO 98%, DARB 89%). In both groups, 99% of patients achieved hematologic response by week 24. The mean cumulative dose during the first 12 weeks (initiation phase) was EPO 141,481 +/- 32,426 units and DARB 499 +/- 152 microg. The 24 week mean cumulative dose (initiation and maintenance phase) was EPO 243,715 +/- 39,264 units and DARB 902 +/- 265 microg, corresponding to a drug cost of EPO $2,966 and DARB $3,933 and a dose ratio of 270:1 (units EPO:microg DARB).
Conclusion: Extended dosing frequency (> or = Q2W) was common in both groups. EPO treatment was associated with a significantly greater hematologic response at early time points (weeks 4, 8, and 12). Erythropoietic agent cost was 33% higher in the DARB group.