A multicenter retrospective cohort study of practice patterns and clinical outcomes of the use of darbepoetin alfa and epoetin alfa for chemotherapy-induced anemia

Abstract

Background: Darbepoetin alfa is the second erythropoietic protein to be approved for the treatment of chemotherapy-induced anemia (CIA). In the clinical setting, darbepoetin alfa can be administered less frequently than epoetin alfa with similar efficacy. Practice patterns and outcomes associated with the use of darbepoetin alfa and epoetin alfa in the clinical setting have not been reported. Objective: This study compared practice patterns and clinical outcomes of the use of darbepoetin alfa and epoetin alfa for CIA at oncology practices in the United States. Methods: This was a multicenter retrospective cohort study. Data were abstracted from the medical charts of consecutive patients who began darbepoetin alfa treatment between August 1 and October 4, 2002, or epoetin alfa treatment between April 1 and July 31, 2002, and were receiving concurrent chemotherapy. These data were used to determine the initial dose and dosing schedule, dose changes, and changes in hemoglobin concentrations after 4, 8, and 12 weeks of treatment, adjusted for red blood cell (RBC) transfusions, and the incidence of RBC transfusions over time. To minimize potential bias, the study protocol defined specific end points and prespecified analytic techniques for assessing clinical outcomes with the 2 agents. Results: The records of 1391 patients from 16 community and hospital outpatient oncology clinics were abstracted. Of these, 1293 patients (93.0%) received only 1 erythropoietic agent (darbepoetin alfa, 735 [56.8%]; epoetin alfa, 558 [43.2%]); the remainder received both agents. In the patients who received darbepoetin alfa, most (553 [75.2%]) received an initial dosage of 200 μg q2wk. A similar proportion (414 [74.2%]) received epoetin alfa at an initial dosage of 40,000 U qwk. As these were the regimens for the majority of patients whose records were abstracted, the results reported here are for these patients. The dose was increased in 63 darbepoetin alfa recipients (11.4%) and 58 epoetin alfa recipients (14.0%) at a median of 7 weeks. After 12 weeks, the 2 groups had an identical mean imputed change from baseline in hemoglobin concentration (1.0 g/dL), and the incidence of RBC transfusions during treatment was also similar between groups (darbepoetin alfa, 44 553 [8.0%]; epoetin alfa, 39 414 [9.4%]). Conclusions: Darbepoetin alfa 200 μg q2wk was used as a standard regimen for CIA at the 16 US oncology practices participating in this study. It appeared to be as effective as epoetin alfa 40,000 U qwk, with a reduced frequency of dosing.