Objective: Few observational studies have evaluated the use of epoetin alfa (EPO) and darbepoetin alfa (DARB) in chronic kidney disease (CKD) patients with anemia. The objective of this study was to investigate dosing patterns, hematologic outcomes, and intervention costs with EPO and DARB in anemic CKD patients treated in an ambulatory care setting.
Methods: This was a multicenter, retrospective, chart review of predialysis CKD patients with anemia treated with EPO or DARB. Charts were sequentially selected from 435 EPO and 432 DARB patients naive to erythropoietic therapy and treated for > or = 24 weeks. Hemoglobin (Hb) levels, dates, and EPO/DARB doses were recorded. Drug costs using 2005 wholesale acquisition costs (WAC) and Federal Supply Schedule (FSS) pricing were based on the mean cumulative drug dose over the 24-week study period.
Results: A total of 393 EPO and 396 DARB charts met all criteria with predominantly male subjects (EPO: 94%; DARB: 96%). Mean baseline GFR and Hb levels were similar. Once-weekly and extended dosing (> or = Q2W) was common in both groups. At Weeks 4, 8, and 12 following initiation of therapy, a greater proportion of EPO than DARB patients reached target Hb levels (> or = 11 g/dL) (p < 0.0001); at Week 24, all patients reached target Hb levels. Mean 24-week cumulative doses were EPO 279 336 +/- 68 302 units and DARB 1084 +/- 246 microg. Drug cost was higher for DARB independent of pricing utilized (WAC: EPO = 3400 US dollars, DARB = 4726 US dollars; FSS: EPO = 1528 US dollars, DARB = 2379 US dollars).
Conclusions: Extended dosing (Q2W) was common in EPO- and DARB-treated patients with CKD-related anemia, with EPO-treated patients experiencing a significantly greater hematologic response (at Weeks 4, 8, and 12). In addition, drug cost was 39-56% higher in the DARB group. The male predominance may limit generalizability, warranting further research in other populations.