Article Abstract

Harmonization of red blood cell distribution width (RDW): an attainable target?

Authors: Giuseppe Lippi, Silvia Pipitone, Emmanuel J. Favaloro


Background: Although red blood cell distribution width (RDW), an indirect measure of anisocytosis, is receiving increasing interest as a diagnostic and prognostic factor in a vast array of human disorders, harmonization of this measure remains an unmet target. In the current study, we explored whether a novel statistic approach may help achieving a major degree of harmonization for this measure.
Methods: The first part of the study was based on measurement of six reference samples with four different hematologic analyzers (Siemens Advia 2120, Sysmex XE5000, Mindray BC6800, Abbott Sapphire). A polynomial curve was constructed by interpolating the values obtained with the four analyzers. The validation study was based on measurement of 126 inpatient samples analyzed with the same four instruments. The raw values and those recalculated according to the coefficients of the polynomial curves were finally compared.
Results: The distribution of raw values obtained with the four hematological analyzers was always significantly different, but in no case did the differences remain significant after RDW values were recalculated with instrument-specific polynomial curves. The man bias of RDW values obtained with the different hematological analyzers could be considerably reduced after recalculation of values. In all cases except one the slopes and the intercepts of the Deming’s fits were significantly improved after recalculation.
Conclusions: The results of this pilot study show that a major degree of harmonization of RDW values measured by different hematological analyzers may be simply achieved by recalculating values according to instrument-specific polynomial curves.