Dosing Patterns and Transfusion Use in Cancer Patients Treated with Erythropoietic Agents: Results of an Observational Study of over 8,000 Patients.

Background: Epoetin alfa (EPO) and darbepoetin alfa (DARB) are FDA approved for the treatment of chemotherapy-related anemia in patients with non-myeloid malignancies. To understand current utilization patterns, this retrospective study examined real-world EPO and DARB treatment patterns (administration frequency, dosing, and treatment duration), frequency of physician visits, and red blood cell (RBC) transfusion use in adult patients with cancer.

Methods: An analysis of medical claims from July 2002 through February 2005 using the Integrated Health Care Information services (IHCIS) national database, which encompasses over 35 health plans, was conducted. Patients included in the study were ≥ 18 years old, had ≥ 1 claim for cancer within 90 days prior to treatment initiation, were newly initiated on EPO or DARB, and received ≥ 2 treatment doses. Patient dosing frequency was classified into three mutually exclusive categories: (a) once weekly (QW; ≤ 9 days), (b) once every other week (Q2W; 9.1 to 18 days), and (c) once every three weeks or longer (≥ Q3W; >18 days), based on the average dosing interval during treatment. Dose only ratio (Units EPO: mcg DARB) was calculated using the ratio of cumulative dose of erythropoietic agents. Frequencies of outpatient hematologist and/or oncologist visits were summarized for EPO and DARB patients. RBC transfusions were identified using the medical procedure codes and the proportion of patients transfused was compared between the two groups.

Results: 5,796 EPO and 2,226 DARB patients met inclusion criteria. Patients receiving EPO were slightly older (59.1 vs. 57.5 years, P<.001) with a lower proportion of female patients (62% vs. 67%, P<.001), compared to those patients receiving DARB. Variability of administration frequency was observed in both treatment groups (EPO: QW 53%, Q2W 38%, ≥ Q3W 9%; DARB: QW 11%, Q2W 67%, ≥ Q3W 22%). Mean treatment duration was similar for both groups (EPO: 58 days; DARB: 59 days; p=0.339). The mean cumulative dose was 269,811 Units for the EPO group and 1,154 mcg for the DARB group, corresponding to a dose only ratio of 234:1 (Units EPO: mcg DARB). While the majority of patients received fixed dosing of EPO 40,000 Units and DARB 200 mcg, extended dosing intervals (≥ Q2W) observed with both agents resulted in a mean weekly EPO dose of 29,281 Units and mean weekly DARB dose of 114 mcg. Frequencies of outpatient hematologist or oncologist visits during treatment were similar between the two groups (visits: 7.7 for EPO vs. 7.5 for DARB, P=0.462). Finally, RBC transfusion was administered to 6.9% of EPO patients compared to 8.4% of DARB patients (p=0.023).

Conclusion: The treatment patterns and dose only ratio from the current study provide greater understanding of the relative effectiveness of these two erythropoietic agents. This observational study of over 8,000 patients shows that the dose only ratio from EPO to DARB is 234:1, frequencies of outpatient hematologist or oncologist visits are similar across the two groups, and transfusion rate is significantly lower in patients treated with EPO, compared to patients treated with DARB. These findings confirm similar results from past research.