Correction towards Normal Hemoglobin Values in Chronic Kidney Disease: What Is the Current Evidence regarding Mortality and Morbidity Outcomes?

Abstract

Background: Recent studies, in which the cardiovascular risk and mortality associated with high and low hemoglobin target values, respectively, have been investigated, challenged the concept that hemoglobin normalization improves prognosis. Methods: The results of these studies are reviewed with respect to differences in study populations, study design and methodological limitations to provide guidance for their interpretation and relevance for clinical practice. Results: There are important differences with respect to enrolled populations, design and conduct of the studies. Each study has its specific, inherent methodological limitations. Importantly, there is no statistically significant and consistent pattern of negative results for cardiovascular and mortality outcomes, although in general outcomes are not in favor of hemoglobin normalization. On the other hand, the reported data on quality of life are consistently and significantly better with higher hemoglobin values. Conclusions: Recent evidence from large outcome studies suggested an increased risk associated with hemoglobin normalization. On the other side, several study-inherent and methodological limitations must be considered before simply extrapolating the negative findings of these studies into clinical practice. However, until new evidence becomes available from ongoing and future clinical studies, an upper Hb limit of 12 g/dl should not be exceeded.