Comparison of Epoetin Alfa and Darbepoetin Alfa Dosing and Costs in an Inpatient Population with Myelodysplastic Syndromes

Background: Prevalent in the majority of patients at diagnosis, anemia associated with myelodysplastic syndromes (MDS) may increase in incidence and severity during the course of the disease. Red blood cell (RBC) transfusion support is often used to manage symptomatic anemia. Epoetin alfa (EPO) and darbepoetin alfa (DARB), two erythropoiesis-stimulating agents (ESAs), are frequently used as supportive care in the treatment of MDS-related anemia to reduce RBC transfusions. To date, limited information on dosing patterns and the associated costs of these agents for MDS patients in the hospital inpatient setting is available. This study examined cumulative ESA dosing and costs in MDS patients treated with ESAs in acute care hospitals.

Methods: An analysis of electronic inpatient records from the Premier Perspective Comparative Hospital Database was conducted. The Premier database encompasses detailed inpatient services from patients admitted to more than 500 hospitals nationwide. A retrospective parallel-group design was used to compare two cohorts of MDS patients treated with EPO or DARB during their hospitalization. Study subjects were identified through hospitalization records between 4Q2006 and 1Q2008. Patients were ≥18 years of age, had an admitting diagnosis of MDS (ICD-9 codes: 238.72–238.75), and were treated with EPO or DARB during their hospital stay. Patients were excluded if they had cancer, received renal dialysis, or were treated with both ESAs. To minimize effect of outliers, 2% of patients, based on the upper and lower 1% patients with extreme doses in each group were excluded from the dosing analysis. Mean cumulative dose and July 2008 wholesale acquisition costs (EPO: $13.13/1,000 Units, DARB: $4.722/mcg) were used to calculate ESA costs.

Results: A total of 3,312 inpatient stays were identified with a primary or secondary diagnosis of MDS (EPO: 2,719, DARB: 593). Mean age and gender distribution were comparable between groups (age: EPO 77.5 years, DARB 78.0 years; % women: EPO 49.4%, DARB 49.2%, p>.05 for both). Mean hospitalization length of stay was also similar for both groups (EPO: 8.8 days; DARB: 8.9 days; p>.05). The two groups were also comparable in terms of medical history at baseline, including hypertension, diabetes mellitus, cardiovascular disease, congestive heart failure, febrile neutropenia, chronic kidney disease, and sepsis. The mean cumulative dose per inpatient stay was 59,379 ± 66,002 Units for EPO and 230 ± 239 mcg for DARB, corresponding to a dose ratio of 258:1 (Units EPO: mcg DARB). Mean cumulative dose of EPO and DARB remained relatively stable over the period from 4Q2006 to 1Q2008. ESA treatment cost per inpatient stay was significantly lower in the EPO group, compared with DARB (EPO $780 vs. DARB $1,085; P<.0001). Sensitivity analysis including the 2% of outliers in each group corroborated the study findings.

Conclusions: The current study, based on recent real-life clinical practice data from an inpatient setting, observed a dose ratio of 258:1 (Units EPO: mcg DARB) in patients with MDS. Based on the cumulative dose administered during hospitalization, EPO was associated with a cost savings of 28% compared to DARB. These results are similar to those observed in MDS patients in the outpatient setting and consistent with reported findings in the chronic kidney disease and oncology populations both in outpatient and inpatient settings.