Economic Evaluation of Weekly Epoetin Alfa versus Biweekly Darbepoetin Alfa for Chemotherapy-Induced Anaemia

Introduction: A 16-week, open-label, multicentre, randomised trial of weekly epoetin alfa 40 000 units versus biweekly darbepoetin alfa 200µg among 358 patients with solid-tumour cancers and chemotherapy-induced anaemia demonstrated superior haematological outcomes with epoetin alfa. We sought to compare resource use, costs and clinical outcomes between treatment groups and report the results using a cost-consequences framework.

Methods: Pre-specified methods were used to assign costs ($US, year 2004–5 values) to medical resources and patient time using a societal perspective. Costs for inpatient care, outpatient care and physician services were based on US Medicare reimbursement rates. Indirect costs assigned to patient time spent receiving study medication were based on the mean hourly wage in the US. In the base-case analysis, the average wholesale price was used to assign costs to medications. Clinical outcomes included all haemoglobin levels and transfusions recorded throughout the trial. Sensitivity analyses were performed to evaluate the impact of different costing methods, cost sources, perspectives and methods to assign haemoglobin values following a blood transfusion.

Results: Over a mean follow-up duration of 11.8 weeks, the average cost of study medications and their administration was the single largest component of total costs and was similar between groups (epoetin alfa $US5979 and darbepoetin alfa $US5935, difference $US44; 95% CI −590, 692). There were no significant differences in the proportions of patients hospitalised (epoetin alfa 24.6%, darbepoetin alfa 22.0%; p = 0.57). Patients randomised to epoetin alfa experienced more inpatient days, on average, than patients randomised to darbepoetin alfa (2.6 vs 1.6, 95% CI for the difference, 0.07, 2.27). However, with regard to transfusions, patients in the epoetin alfa arm required fewer units of blood than patients in the darbepoetin alfa arm (0.46 vs 0.88, 95% CI for the difference −0.77, −0.08). Mean total costs, comprising costs for study medications and their administration, inpatient care, transfusions, unplanned radiation therapy, haematology and laboratory services, chemotherapy and non-chemotherapy drugs and indirect costs were $US14 976 in the epoetin alfa arm compared with $US14 101 in the darbepoetin alfa arm, a difference of $US875 (95% CI for difference −849, 2607), of which 98% of the difference was attributable to higher inpatient costs in the epoetin alfa arm ($US2374 vs $US1520; 95% CI for difference −33, 1955). Assessments of multiple clinical measures demonstrated improved outcomes with epoetin alfa relative to darbepoetin alfa.

Conclusion: Most clinical outcome measures suggested greater improvement with epoetin alfa relative to darbepoetin alfa, but most costs for both agents appeared similar. Decision makers must evaluate the differences in costs and efficacy measures that are most relevant from their perspectives.