Objective: To investigate the dosing patterns and treatment costs of erythropoietic agents in adult (>or= 18 years of age) cancer patients newly initiated on epoetin alfa (EPO) or darbepoetin alfa (DARB) in managed care organizations.
Methods: An analysis of US medical claims (30 million lives in over 35 health plans) in the period July 1, 2002-February 28, 2005 was conducted. Patients with >or= 1 cancer claim within 90 days prior to initiating EPO or DARB, and who received at least two doses of the same erythropoietic agent, were included in this analysis. Weighted average weekly dosing, cumulative treatment dose, associated drug cost, dosing frequency patterns, and the frequency of outpatient visits were evaluated. The EPO:DARB dose ratio, based on average cumulative treatment doses, was assessed.
Results: 5639 EPO and 2166 DARB patients met the inclusion and exclusion criteria. The EPO group was older (EPO 59.1 years; DARB 57.6 years; p < 0.001) with a higher proportion of men (EPO 38.1%; DARB 33.1%; p < 0.001). Variable dosing frequency was observed with similar treatment durations for the two groups (days: EPO 55.6; DARB 57.7; p = 0.122). A dose ratio of 236:1 was observed (average cumulative dose: EPO 252 856 U; DARB 1072 mcg). Average drug cost was significantly higher in the DARB group (drug cost: EPO 3077 dollars; DARB 4674 dollars; p < 0.001). The average number of hematology/oncology outpatient visits per patient (visits: EPO 7.4; DARB 7.3; p = 0.676) and outpatient visits for hemoglobin determination (visits: EPO 6.7; DARB 6.4; p = 0.093) during treatment was similar between the two groups.
Limitations: The results were based on medical claims only. The absence of information on actual injection dates in pharmacy claims prevented their incorporation in the analysis.
Conclusions: Based on the average cumulative doses, the EPO:DARB dose ratio was 236:1 (Units EPO: mcg DARB) with 52% greater drug cost in the DARB group. Despite the variable administration frequency observed between the two agents, the number of hematology/oncology outpatient visits was not different.