Abstract
BackgroundThis study was designed to evaluate if erythropoietin (EPO) is effective in the treatment of cancer related anemia, and if its effect remains unchanged when data are analyzed according to various clinical and methodological characteristics of the studies. We also wanted to demonstrate that cumulative meta-analysis (CMA) can be used to resolve uncertainty regarding clinical questions.MethodsSystematic Review (SR) of the published literature on the role of EPO in cancer-related anemia. A cumulative meta-analysis (CMA) using a conservative approach was performed to determine the point in time when uncertainty about the effect of EPO on transfusion-related outcomes could be considered resolved. Participants: Patients included in randomized studies that compared EPO versus no therapy or placebo. Main outcome measures: Number of patients requiring transfusions.ResultsNineteen trials were included. The pooled results indicated a significant effect of EPO in reducing the number of patients requiring transfusions [odds ratio (OR) = 0.41; 95%CI: 0.33 to 0.5; p < 0.00001;relative risk (RR) = 0.61; 95% CI: 0.54 to 0.68]. The results remain unchanged after the sensitivity analyses were performed according to the various clinical and methodological characteristics of the studies. The heterogeneity was less pronounced when OR was used instead of RR as the measure of the summary point estimate. Analysis according to OR was not heterogeneous, but the pooled RR was highly heterogeneous. A stepwise metaregression analysis did point to the possibility that treatment effect could have been exaggerated by inadequacy in allocation concealment and that larger treatment effects are seen at hb level > 11.5 g/dl. We identified 1995 as the point in time when a statistically significant effect of EPO was demonstrated and after which we considered that uncertainty about EPO efficacy was resolved.ConclusionEPO is effective in the treatment of anemia in cancer patients. This could have already been known in 1995 if a CMA had been performed at that time.
Highlights
This study was designed to evaluate if erythropoietin (EPO) is effective in the treatment of cancer related anemia, and if its effect remains unchanged when data are analyzed according to various clinical and methodological characteristics of the studies
The variables related to the design and clinical features which possible could affect the treatment effect of EPO were entered in the equation We found no statistically significant association between any of the variables with the treatment effect of EPO when all data were simultaneously entered in a multiregression equation(data not shown)
Our findings suggest that 65% of the cancer patients included in this Systematic reviews (SR) participated in placebo controlled clinical trials that were reported after EPO was shown to be superior to placebo
Summary
This study was designed to evaluate if erythropoietin (EPO) is effective in the treatment of cancer related anemia, and if its effect remains unchanged when data are analyzed according to various clinical and methodological characteristics of the studies. Some randomized trials (RCT) assessed the role of EPO in anemia related the cancer [2,3]. Many of these trials were underpowered and failed to identify clinically meaningful benefits of EPO treatment. A recent comprehensive SR [5,6] addressed the role of EPO in treatment-related anemia in cancer patients. This SR included non-randomized studies and performed a meta-analysis (MA) of 12 RCTs showing a significant effect of EPO in reducing the need to transfuse patients who are receiving chemotherapy. Some issues were not addressed in this previous SR/MA: a formal quantitative synthesis (meta-analysis) was not performed according to different clinical aspects and to main methodological quality dimensions empirically linked to bias [7]
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