B-048 New technology for Erythrocyte Sedimentation Rate (ESR). Comparison between automated measure and modified Westergren method in pediatric population. Is a change of methodology possible?

Abstract

Background ESR is based on the principle that the sedimentation of red blood cells in plasma provides an indirect measure of the level of acute-phase proteins and therefore of inflammation, assessing the acute phase response in pathological conditions. Although the International Council for Standardization in Hematology (ICSH) considers the Westergren as the reference method, the larger sample volume required limits its use in pediatrics. The technical innovations significantly improved on the existing procedures. One of the main advantages of automated systems includes the use of ethylenediaminetetraacetic acid (EDTA) that increases sample stability and allows using a single sample for both ESR and other hematological tests, thus enhancing patient safety, optimizing the workflow and increasing personnel safety by using closed systems and shortening turnaround time. Due to the wide variety of methods available, all new technologies must be evaluated against the Westergren reference method before being introduced into clinical use. The aim of this study was to evaluate ESR values obtained by an automated analyzer which integrates measurement of ESR with routine complete blood count (CBC) compared with modified Westergren method (ESRw) currently used. Methods Outpatients and hospitalized pediatric patients (1-18 years) were included (n=120). The manual measurement (3.8% sodium citrate tubes, 1 ml, Vitis®) using the ESRw was performed according to the ICSH’s recommendations. The Mindray? BC 6800 Plus ESR was measured in 1.3 ml EDTAK3 tubes (Tecnon®), simultaneously with CBC. Samples were stored at room temperature and analyzed by a dedicated technologist within 4 hours of collection. The analyzer measures ESR value using near-infrared photometry to determine the degree of red blood cell aggregation that occurs in the first phase (rouleaux formation) of sedimentation. Reportable ESR parameter (ESRm) and the Research-Use-Only ESR-correction parameter (ESRmc, independent of hematocrit value) were performed. The data was statistically analyzed and compared among different methods: Pearson correlation, Bland-Altman and Passing-Bablok (p-value < 0.05 was considered statistically significant). Results Both ESRm and ESRmc methods show very good correlation with the reference method: 0.9081 and 0.9169 respectively. Although ESRm has a very good correlation, it shows an associated systematic and proportional error, which is not observed in ESRmc (Figure 1-4). Conclusion Automation of ESR measurement is currently an attractive alternative even more in the pediatric population, where the sample volume is usually a limitation and the turnaround time of the results is critical. Taking this into account, the new technology allows the same sample used for CBC and provides results in 90 seconds. However, validation and comparison against the Westergren reference method is required. If the change of methodology is established, the existence of a bias should be considered when ESRm is used, especially at high values. The parameter that showed the highest comparability was found to be ESRmc. However, given that it’s a research-use-only parameter, it cannot be included in the clinical report currently.