Survey material choices in haematology EQA: a confounding factor in automated counting performance assessment

Abstract

The complete blood count (CBC) is one of the most frequently requested tests in laboratory medicine, performed in a range of healthcare situations. The provision of an ideal assay material for external quality assessment is confounded by the fragility of the cellular components of blood, the lack of commutability of stabilised whole blood material and the lack of certified reference materials and methods to which CBC results can be traced. The choice of assay material between fresh blood, extended life assay material and fully stabilised, commercially prepared, whole blood material depends upon the scope and objectives of the EQA scheme. The introduction of new technologies in blood counting and the wider clinical application of parameters from the extended CBC will bring additional challenges for the EQA provider.

Formation and Evaluation of Complete Blood Count Proficiency Testing Program

“…This preparation method was based on WHO guidelines [ 4 ] and has been applied by many EQA providers worldwide. The stability of the EQA material produced by this method can be prolonged for several weeks [ 8 ]. Thus, this material can be produced in large volumes for the CBC EQA scheme at a reasonable cost in Vietnam.…”

“…Whole-blood specimen pools were dispensed, bottled, and stored at 2–6 °C for up to 4 months. The total of 150 2mL aliquots were prepared from each pool, and three level ranges were chosen in this study to make three batches [ 8 , 9 ]: Level 1: RBC (1.5–3.0 10 12 /L), WBC (2–4 10 9 /L), and PLT (40–150 10 9 /L) Level 2: RBC (3.5–4.5 × 10 12 /L), WBC (5–9 × 10 9 /L), and PLT (150–350 × 10 9 /L) Level 3: RBC (4.5–6.0 × 10 12 /L), WBC (9–30 × 10 9 /L), and PLT (400–700 × 10 9 /L) …”

Standardization and harmonization in hematology: Instrument alignment, quality control materials, and commutability issue

“…The HAs have been characterized since the beginning by wide heterogeneity of analytical methods, further amplified by parallel evolution of fluidics, hardware, and software 7 . The development of innovative technologies in flow cytometry has also allowed the commercialization of a new generation of HAs over the past few years, which are capable to reduce the turnaround time (TAT) and generate quantitative and qualitative information, with high degree of analytical efficiency 5,7,8 …”

“…Nonetheless, the rapid technological progress of the latest generation of HAs has not been paralleled by a similar improvement of reference methods and control materials suitable for the CBC 2‐5,7‐10 . HA calibration and optimization still rely on whole‐blood samples of healthy subjects, collected with the appropriate anticoagulant 11 .…”

“…The CBC is a multiparameter analysis, where only a minority of parameters (hemoglobin (Hb), white blood cell (WBC), red blood cells (RBC), mean corpuscular volume (MCV), platelets (PLT), and reticulocytes (RET)) are simultaneously and directly measured by different instrumental channels. Moreover, HAs may use different measurement principles (optical, impedance, fluorescence) to detect cellular characteristics 2‐5,7‐10 . Finally, complexity in development of appropriate control material is proportional to the number of cell classes identified by the HA in the channels for automated differential counts: two‐part differential (polymorphonucleated and mononucleated), three‐part differential (polymorphonucleated, monocytes, and lymphocytes), five‐part differential (neutrophils (NE), eosinophils (EO), basophils (BA), monocytes (MO), and lymphocytes (LY)), or even more.…”