To follow or not to follow the recommendations regarding microscopic analysis of the Clinical and Laboratory Standards Institute H20-A2 to validate the criteria for blood smear review?

Evaluation of the Sysmex DI-60 digital morphology analyzer on Wright-stained samples with a focus on prevalence-dependent quality indicators

BACKGROUND

This study aims to evaluate the trueness of the DI-60 Digital Cell Imaging Analyzer on Wright-stained samples with a focus on prevalence-dependent quality indicators for differential blood counts requested from non-hematology wards.

METHODS

Two hundred and ninety-nine samples were included into this performance evaluation study at the Department of Laboratory Medicine, Medical University of Vienna. The following aspects were verified: (a) the reliability of automatedly pre-classified differential counts, (b) the concordance of DI-60 counts with manual-microscopic differential counts and (c) the agreement of DI-60 and manual-microscopic results regarding clinically relevant findings.

RESULTS

82.3% of all leukocytes were correctly pre-classified. Cell categories with a low prevalence (eosinophils, basophils, progenitors/precursors) in non-hematological patients presented with a low positive predictive value (PPV), indicating a high frequency of false positives. Comparisons between visually adjusted results of the DI-60 and manual-microscopic differential counts revealed a good concordance for neutrophil and lymphocyte counts. Besides the detection of precursors/progenitors and normoblasts, no relevant systemic errors were detected. However, due to their low prevalence and technical aspects, the detection of basophilia, monocytosis or the presence of precursors/progenitors showed comparably low accuracies (error rates of 7.4%-24.1%).

CONCLUSION

The DI-60 system works well for Wright-stained samples collected in the non-hematology ward. Due to the varying prevalence of cell categories found in peripheral blood, a low PPV can be expected with automatic assignment for those cells with low prevalence (e.g., basophils, eosinophils, precursor and progenitor cells, plasma cells). If the pre-test probability of these conditions is increased, manual microscopic processing may be recommended.

Evaluation of the WBC-differential flagging performances and accuracy of the HORIBA Yumizen H2500 cell counter in oncology patients from a single institution

INTRODUCTION

The Yumizen H2500 (YH2500) cell analyser was compared to the Pentra DX Nexus (both from HORIBA Medical) to evaluate the efficiency of the new YH2500 technology for the WBC-differential in samples from oncology patients with WBC-diff abnormalities.

MATERIAL AND METHODS

The 220 samples with slide review criteria on the Nexus were systematically analysed on the YH2500. The WBC-diff was compared to flow cytometry (FCM). The 100 additional samples with Monocyte/Neutrophil separation flags were evaluated. The flagging performance and the accuracy of the WBC-diff were analysed.

RESULTS

The YH2500 generated fewer flags than the Nexus (47.73% vs 66.64%; p < .0001), except for Monocyte/Neutrophil flag (15.5% vs. 2.7%; p < 0.0001). Overall performances were higher on the YH2500 (Sensitivity, 100 vs. 89.6%; Specificity 81.0% vs. 50.9%; PPV, 74.3% vs. 62.9%; NPV, 100% vs. 69.5%; Efficiency, 87.7% vs. 69.5%). YH2500 showed a statistically significant better correlation with FCM for the 6-part differential than the Nexus. On 134 samples with Monocyte/Neutrophil separation flag, it was shown that, in samples with less than 10% monocytes on the YH2500, the results of monocyte and neutrophil counts were comparable to the manual count, and that these samples did not need a slide review if no other main criterion for review was present.

CONCLUSION

The YH2500 demonstrated better performance characteristics than the previous cell counter, the Nexus. Its implementation in our laboratory routine work significantly improved the practice workflow, decreased the number of manual cell counts and increased the pertinence of slide review and reporting of the microscopic count.

Policies and practices in the field of laboratory hematology in Croatia - a current overview and call for improvement

OBJECTIVES

In 2019 The Croatian Working Group for Laboratory Hematology, on behalf of the Croatian Society of Medical Biochemistry and Laboratory Medicine, wanted to explore the background in field of laboratory hematology routine practice among Croatian laboratories in order to develop future strategies for producing national recommendations, if needed.

METHODS

During April and May 2019, a comprehensive survey covering all main parts of the total testing process within the field of laboratory hematology among Croatian medical laboratories was conducted. The survey comprised 49 inquiries. Data was collected using Survey Monkey (Palo Alto, CA, USA). All collected data was anonymized.

RESULTS

The response rate was 72%. There is still a substantial number of laboratories that have only three-part differential hematology analyzers (9%). Furthermore, a very high number of laboratories did not perform analyzer verification prior to implementation into routine work (31%). Out of those who have verified their analyzers, a diversity of guidelines and recommendations were used. Nearly 10% of the laboratories do not have a defined policy regarding specimen rejection. The majority of the participants perform internal quality control daily (83%), however, only 51% of respondents evaluate the agreement between different hematology analyzers on daily basis. Although more than 90% of Croatian laboratories have a defined policy regarding specimen rejection, only 61% of respondents continuously monitor quality indicators in routine practice.

CONCLUSIONS

The survey revealed substantial differences in all aspects of laboratory hematology practices among Croatian medical laboratories, indicating the need for universal recommendations at the national level.

Evaluation of criteria of manual blood smear review following automated complete blood counts in a large university hospital

Background

There is great interest in reducing the number of automated complete blood counts requiring manual blood smear reviews without sacrificing the quality of patient care. This study was aimed at evaluating and establishing appropriate screening criteria for manual blood smear reviews to improve the performance in a hematology laboratory.

Method

A total of 1977 consecutive samples from the daily workload were used to evaluate four sets of screening criteria for manual blood smear reviews to identify samples with positive smear findings. Three sets of screening criteria were arbitrarily proposed in this study: Group 1 (narrow ranges), Group 2 (intermediate ranges), and Group 3 (wide limits) and one set (Group 4) was adapted from the International Society for Laboratory Hematology. All samples were run on Sysmex hematology analyzers and were investigated using manual blood smear reviews. Diagnostic accuracy and agreement were performed for each set of screening criteria, including an investigation of microscopic review rate and efficiency.

Results

The microscopic review rates for Groups 1, 2, 3 and 4 were 73.85%, 54.52%, 46.33% and 46.38%, respectively; the false-negative rates were 0.50%, 1.97%, 2.73% and 3.95%, respectively. The efficiency and negative predictive values of Group 3 were 73.04% and 4.91%, respectively.

Conclusions

Group 3 had the best relationship between safety (false-negative rate: ≤3%) and efficiency to estimate the limits of automation in performing complete blood counts. This study strengthens the importance of establishing screening criteria for manual blood smear reviews, which account for the different contexts in which hematological determinations are performed. Each laboratory should optimize the screening criteria for manual blood smear reviews in order to maximize their efficiency and safety.