Abstract
Background: Epoetin alfa (EPO) and darbepoetin alfa (DARB) are commonly used for the treatment of chemotherapy-induced anemia (CIA). To date, three randomized head-to-head studies have compared EPO dosed 40,000 Units once weekly (QW) and DARB dosed 200mcg once every two weeks (Q2W). As transfusion results across these studies were inconsistent a meta-analysis was undertaken to provide a pooled estimate of the comparative difference in red blood cell transfusion rates between DARB and EPO treatment groups.Methods: Demographic and transfusion rate data were extracted from the three publicly available head-to-head comparison studies (pooled N=940 for DARB and N=933 for EPO). Odds ratios, risk ratios and risk differences of transfusion rates from week 1 to the end of treatment between DARB and EPO groups were analyzed using both fixed- and random-effects meta-analysis methods; the latter incorporated between-study variation in addition to within-study variation. A multivariate logistic regression model weighted by the number of patients in each study arm and including population-level characteristics from each study arm, was conducted to isolate the treatment effect on the risk of transfusion after controlling for differences in baseline characteristics between DARB and EPO patients.Results: Fixed- and random-effects models generated similar results (p>0.42 for homogeneity test across studies), both demonstrating that the DARB Q2W group had a statistically significantly higher transfusion rate than the EPO QW group. Using the random-effects model, the odds ratio of transfusion in the DARB group was 1.28 of that in the EPO group (95%CI: 1.03– 1.59). The corresponding risk ratio and risk difference were 1.21 (95%CI: 1.02–1.43) and 4% (95%CI: 0.3%–8%), respectively. Multivariate regression analysis further confirmed DARB Q2W had a higher transfusion rate compared to EPO QW, after controlling for age, baseline hemoglobin and the proportion of breast cancer patients (adjusted odds ratio=1.45, 95%CI: 1.10–1.91).Conclusion: This meta-analysis demonstrates that, in patients with CIA, EPO 40,000 units QW is more effective at reducing RBC transfusion requirements than DARB 200 mcg Q2W.
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