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

Report of the International Council for Standardization in Haematology working group for standardization of reticulocyte parameters

INTRODUCTION

The International Council for Standardization in Haematology convened a working group to assess and propose improvements upon the state of standardization and harmonization of reticulocyte parameters among commercial hematology analyzers.

METHODS

An international group of laboratory hematologists prospectively collected and analyzed clinical samples using locally available IVD commercial hematology analyzers. Eight hundred and fifty-five total samples were collected at 6 sites using 9 distinct analyzer types. Samples were assessed for reticulocyte percent (RET%), immature reticulocyte fraction (IRF), and reticulocyte hemoglobin content (RHC). Method comparison and regression statistics were calculated. These analyses were used to determine whether statistical recalibration offered a potential avenue for increasing comparability between these methods.

RESULTS

While methods producing reticulocyte percent were the most comparable in this study, the state of harmonization for the IRF and RHC was reduced with pearson correlation coefficients ranging from 0.955 to 0.77 and 0.927 and 0.680, respectively. Nevertheless, use of parameters from the Passing Bablok regression substantially improved the comparability of the results. In addition, precision data was derived which also demonstrated substantial differences between analyzer systems.

CONCLUSION

While reticulocyte counting is correlated between the automated methods evaluated in this study, the current state of harmonization of other reticulocyte parameters is not as strong. A major challenge in moving this field forward is the need for commutable materials to facilitate comparisons between analyzers not co-located. A potential alternate approach to improve the current state would be instrument re-calibration. However, this is challenging both technically and due to national regulatory frameworks.

Navigating Quality Assessment Hurdles in Clinical Laboratory Services: A Comprehensive Review in Resource-Limited Settings

External quality assessment is the process of evaluating the performance of a laboratory and the competence of professionals. Participation in EQA and standardizing the quality of laboratory services are a mandatory requirements for accreditation. This review is aimed at identifying and discussing challenges that hinder the effective implementation of an EQA program in countries with resource limited setting. To obtain abundant information, articles were identified by searching the literature publishedin English using the National Library of Medicine, PubMed, Science Direct and AMC digital library databases. The articles identified in the references were manually searched and included. After the article was identified, it was imported to Endnote version 8.1 and exported to Microsoft Word for citation. Based on this review, the major identified challenges that hinder the implementation of an EQA program include the high cost of control materials, malfunction and lack of maintenance for equipment failure and breakdown, a knowledge gap among laboratory professionals, noncommutability of control samples, and difficulty in assigning target values. In addition, failing to participate in EQA and failing to take corrective action are the major challenges identified. As a result, applying to an EQA program in resource-limited counties was highly challenging. To attain high performance in the laboratory and to provide quality laboratory service for patient care, the EQA supplier and the user laboratory must pay attention to these issues and take appropriate corrective actions for ongoing quality improvement and accreditation.

Formation and Evaluation of Complete Blood Count Proficiency Testing Program

Introduction: The haematology external quality assessment (EQA) scheme is the most commonly used service of quality assurance. The provision of complete blood count (CBC) materials must meet the quality requirements at a reasonable cost. These requirements are the most significant challenges for EQA organisers in Vietnam. This study’s objective was to evaluate the homogeneity, long-term stability, and peer-group performance of 10-parameter stabilised CBC EQA samples. Methods: The CBC EQA material was prepared using the following steps, including (1) adjusting levels of stabilised erythrocyte, leukocyte, and platelet samples, (2) mixing those cells into batches at three levels, and (3) dispensing and storing them at 2–6 °C. A set of 10 and 30 specimens were randomly chosen from each batch to study the homogeneity and long-term stability following ISO 13528:2015. In total, 166 samples at two levels were randomly distributed to 40 participants, which reported 83 automatic cell counters among six automated analyser models in the CBC EQA program. Results: The 10-parameter stabilised CBC EQA materials at three levels became homogeneous and stable in 12 weeks when preserved at 2–6 °C. Meanwhile, for five parameters (RBC, Hb, MCH, MCV, and MPV), this process was prolonged for up to 16 weeks in stock condition. In terms of peer-group performance, the CV (%) values increased at the low concentration for almost all parameters, especially in platelet counts. Conclusions: The stabilised CBC EQA samples prepared using the partial fixation method with aldehyde and gutaraldehyde in this study meet the ISO 13528:2015 requirements of homogeneity and long-term stability for the CBC EQA scheme. Analytical performance evaluation should categorise participant methods into peer groups.

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

INTRODUCTION

In the hub and spoke laboratory network, the number of hematology analyzers (HAs) within each core center has increased, and the control of HAs alignment is becoming necessary requirement to ensure analytical quality. In this scenario, HA alignment can be assessed by analyzing the same control material used for internal quality control on multiple HAs, assuming its commutability. The aim of the study was to verify the applicability of a protocol for the alignment of HAs based on control material rather than on fresh whole-blood samples.

METHODS

The alignment of five HAs was evaluated for red (RBC, Hb, MCV, RET), white (WBC, NE, LY, MO, EO, BA, IG), and platelet (PLT) series parameters, following a protocol by SIBioC, using human sample (HS) and quality control material (QC), after the verification of commutability, according to the IFCC protocol. Maximum bias was derived from biological variation data.

RESULTS

A complete alignment between instruments was confirmed for the majority of the parameters investigated both for HS and QC material. Partial misalignments or inconcludent results were instead evident for MCV, MO, EO, BA, and IG. Interestingly, QC material was found to be not commutable for LY, MO, and BA.

CONCLUSION

The alignment of hematologic analyzers for main cell population parameters may be verified with both QC and HS, displaying consistent results and interpretation. The evaluation for some white series parameters (EO, BA, and IG) is critical, and particular attention must be paid to the values of the material used for the alignment.

Total haemoglobin – a reference measuring system for improvement of standardisation

Background

Total haemoglobin (Hb) concentration in blood belongs to the most requested measurands, and the HiCN method (hemiglobincyanide) is accepted as a reference. Although the reaction principle is clearly characterised, measurement conditions and settings are not consistently defined, some of them influencing the results. An improvement of standardisation is the object.

Methods

After method optimization, measurement results between different calibration laboratories (CL) were compared with each other and also with results of the National Metrology Institute of Germany (PTB), with target values of certified reference material, within the RELA scheme, and to >1500 results from routine laboratories.

Results

Overall deviations between three CLs were ≤0.5% (n = 24 samples) in a measurement range of 20 g/L to 300 g/L. A CV of 0.4% was determined in pooled blood (1 year long-term imprecision, 99.0%–101.1% recovery of the mean). For selected measurements (n = 4 samples) the PTB participated without significant differences to three CLs, and no significant differences were observed comparing CLs to certified values of reference materials. The expanded measurement uncertainty (probability 95%) was estimated as 1.1%.

Conclusions

A reference measuring system, comprising measuring instruments and other devices, including reagents and supply, to generate reference measurement values for total Hb concentration of high accuracy and low measurement uncertainty is presented. Measurement parameters are investigated and defined. The reference measuring system is ready to offer service to EQA providers and to the IVD industry for certifying control materials or calibrators.