PS1199 SCREENING FOR HEREDITARY SPHEROCYTOSIS IN DAILY PRACTICE: WHICH IS THE BEST ALGORITHM USING ERYTHROCYTE AND RETICULOCYTE PARAMETERS?

Abstract

Background:Hereditary spherocytosis (HS) is the most common inherited chronic haemolytic anemia in Northern Europe. Its prevalence is estimated to 1 in every 2000 births. The actual guidelines for the screening and diagnosis of HS are based on clinical and family histories, physical examination and laboratory findings. Additional parameters based on complete blood count (CBC) and reticulocyte parameters have been developed on haematology analyzers leading to many publications about their effectiveness as HS screening tool.Aims:We evaluated and compared the effectiveness of four published algorithms for the screening of HS using two haematology analyzers i.e. the UniCel DxH800 (DxH; Beckman‐Coulter, Miami, FL) and the XN‐9000 (XN; Sysmex, Kobe, Japan) and determined which algorithm could be the most suitable in our daily clinical practice.Methods:A total of 96 EDTA samples obtained for HS screening were analyzed prospectively on both haematology analyzers and a CBC with extended reticulocyte parameters were collected. These included 12 confirmed HS patients and 84 non‐HS patients. The diagnosis of HS was based on clinical and family histories, cryohaemolysis test, eosin‐5’‐maleimide (EMA) dye binding test, ektacytometry and identification of the defective protein. The specific reticulocyte parameters used on the DxH800 were mean reticulocyte volume (MRV), immature reticulocyte fraction (IRF) and mean sphered cell volume (MSCV), and on the XN‐9000 were hypohaemoglobinized erythrocytes (Hypo‐He), microcytic erythrocytes (MicroR) and IRF. For each algorithm, we established sensitivity, specificity, negative predictive value (NPV) and positive predictive value (PPV).Results:The results are reported in Table 1. The only algorithm that provided a sensitivity of 100% was the algorithm published by Lazarova et al. in 2014 using the DxH800. The three algorithms published based on the Sysmex parameters showed much lower performances than the one based on the DxH800 parameters i.e. out of the 96 patients with HS, between 2 to 6 patients were screened as negative for HS. Three of the published algorithms were evaluated on a previous XE model i.e. XE‐5000, mode of HS diagnosis is not always comparable as well as the amount of patients involved in the different studies.Table 1: Performance characteristics of the different algorithms (original stated performance characteristics) tested prospectively on 12 HS and 84 non‐HS patients.Summary/Conclusion:To screen for HS in the daily practice, the extended reticulocyte parameters provided by the Sysmex analyzers seem promising but the clinical cut‐offs on the XN‐9000 should be reevaluated on a larger number of patients.image