First Results of an External Quality Assessment (EQA) Scheme for Molecular, Serological and Antigenic Diagnostic Test for SARS-CoV-2 Detection in Lombardy Region (Northern Italy), 2020–2022

For diagnosing SARS-CoV-2 infection and for monitoring its spread, the implementation of external quality assessment (EQA) schemes is mandatory to assess and ensure a standard quality according to national and international guidelines. Here, we present the results of the 2020, 2021, 2022 EQA schemes in Lombardy region for assessing the quality of the diagnostic laboratories involved in SARS-CoV-2 diagnosis. In the framework of the Quality Assurance Programs (QAPs), the routinely EQA schemes are managed by the regional reference centre for diagnostic laboratories quality (RRC-EQA) of the Lombardy region and are carried out by all the diagnostic laboratories. Three EQA programs were organized: (1) EQA of SARS-CoV-2 nucleic acid detection; (2) EQA of anti-SARS-CoV-2-antibody testing; (3) EQA of SARS-CoV-2 direct antigens detection. The percentage of concordance of 1938 molecular tests carried out within the SARS-CoV-2 nucleic acid detection EQA was 97.7%. The overall concordance of 1875 tests carried out within the anti-SARS-CoV-2 antibody EQA was 93.9% (79.6% for IgM). The overall concordance of 1495 tests carried out within the SARS-CoV-2 direct antigens detection EQA was 85% and it was negatively impacted by the results obtained by the analysis of weak positive samples. In conclusion, the EQA schemes for assessing the accuracy of SARS-CoV-2 diagnosis in the Lombardy region highlighted a suitable reproducibility and reliability of diagnostic assays, despite the heterogeneous landscape of SARS-CoV-2 tests and methods. Laboratory testing based on the detection of viral RNA in respiratory samples can be considered the gold standard for SARS-CoV-2 diagnosis.

Clinical significance of cell population data (CPD) on Sysmex XN-9000 in septic patients with our without liver impairment

BACKGROUND

This study evaluated the clinical significance of cell population data (CPD) parameters obtained on Sysmex XN-9000 in septic patients admitted to intensive care unit (ICU) and stratified according to liver function.

METHODS

The study population consisted in 84 patients, 44 of whom did not develop sepsis (NS), whereas the remaining 40 developed sepsis (SE) (n=24) or septic shock (SS) (n=16). Two hundred ostensibly healthy blood donors [healthy subjects (HS)], undergoing routine blood testing before a regular blood donation, were studied.

RESULTS

Except for neutrophils and lymphocytes cell size (NE-FCS and LY-Z), all other CPD values were significantly different in ICU patients compared to HS. Neutrophils and monocytes fluorescence intensity (NE-SFL and MO-X) values were significantly higher in SS compared to sepsis and not develop sepsis patients. The value of many parameters was also different according to liver function. Overall, MO-X and neutrophils fluorescence intensity (NE-SFL) exhibited the best performance for diagnosing sepsis in all patients (AUC, 0.75 and 0.72), as well as in those with (AUC, 0.95 and 0.89) or without (AUC, 0.72 for both) liver impairment. These parameters were also significantly correlated with Sequential Organ Failure Assessment (SOFA) score.

CONCLUSIONS

This study suggested that some novel CPD parameters (namely NE-SFL and MO-X) may provide useful information for diagnosis and management of sepsis.

Validation rules for blood smear revision after automated hematological testing using Mindray CAL-8000

BACKGROUND

This article was aimed to test the use of validation rules for blood smear review after automated hematological testing using Mindray CAL-8000 (two hematological analyzers and one autoslider).

METHODS

This study was based on 1013 peripheral blood samples (PB) referred for routine hematological testing. Results of testing on CAL-8000 were analyzed using both locally derived and International Consensus Group for Hematology (ICGH) validation rules, and then compared with data obtained by optical microscopy (OM). A workflow analysis was also completed.

RESULTS

The overall agreement with locally derived and ICGH criteria was 91% and 85%, but a higher sensitivity was observed for locally derived criteria (0.97 vs 0.95). The percentage of false negative and false positive samples was 2.1% and 7.1% using ICGH criteria, and was 1.4% and 14% using locally defined rules. The throughput of CAL-8000 system was 208 samples/h, with a percentage of OM analysis comprised between 14% and 17%, and sensitivity of 0.97. As regards personnel activity, we estimated 0.8 full-time equivalent (FTE) of technical staff and 0.7 FTE of personnel for clinical validation of data and blood smear review.

CONCLUSION

These results show that customization of validation rules is necessary for enhancing the quality of hematological testing and optimizing workflow.

Extended leukocyte differential count and C-reactive protein in septic patients with liver impairment: diagnostic approach to evaluate sepsis in intensive care unit

BACKGROUND

Sepsis is still a major cause of death in intensive care units (ICUs) worldwide. Patients with liver impairment express an imbalanced cytokine response which alters common sepsis biphasic nature. Cytokines measurement is expensive, often unavailable, whereas leukocytes (WBC) evaluation performed through hematology analyzers can provide a practical strategy for monitoring inflammatory response.

METHODS

A total of 200 healthy subjects (HS) and 84 patients (18 with, 66 without liver impairment) admitted to ICU, were assessed for International Sepsis Definitions, Sequential Organ Failure Assessment (SOFA) and Model for End-Stage Liver Disease (MELD) scores. We tested 1,022 peripheral blood samples using Sysmex XN-9000, estimating diagnostic accuracy of leukocyte differential count and nontraditional parameters through receiver operating characteristics (ROC) curves analysis compared to clinical classification.

RESULTS

Median value of all-leukocyte parameters was different in ICU patients compared to HS. Leukocytes, neutrophils (NE) and immature granulocytes (IGs) in sepsis and septic shock (SS) were higher than no sepsis (NS), with an area under the curve: 0.81, 0.82 and 0.78 respectively. Lymphocytes (LY) and monocytes (MO) were significantly associated with liver impairment.

CONCLUSIONS

Diagnostic accuracy of all-leukocyte parameters may provide valuable information for diagnosis and follow-up of sepsis in ICU patients, especially those with liver impairment.

Cell Population Data and reflex testing rules of cell analysis in pleural and ascitic fluids using body fluid mode on Sysmex XN-9000

BACKGROUND

Although optical microscopy (OM) remains the reference technique for analysis of ascitic (AF) and pleural (PF) fluids, novel hematological analyzers are equipped with modules for body fluid (BF) analysis. This study was aimed to analyze the performance of XN-BF module in Sysmex XN-9000, and to develop validation rules for automated cell counts in BFs.

METHODS

The evaluation of XN-BF module included assessment of carryover, Limit of Blank (LoB), Limit of Detection (LoD), Limit of Quantitation (LoQ), linearity, data comparison with OM, and development of rules for assisting the validation of automated analysis of BFs and activating reflex testing.

RESULTS

The carryover was negligible. The LoB, LoD, LoQ and linearity were always excellent. The comparison with OM was characterized by Pearson's correlations ranging from r=0.50 to r=0.99 (p<0.001), modest bias and high diagnostic concordance (Area Under the Curve between 0.85 and 0.99). The use of instrument-specific cut-offs further increased diagnostic concordance. The implementation of reflex testing rules based on XN-BF data increased sensitivity and specificity of BFs classification to 0.98 and 0.95.

CONCLUSIONS

Our results suggest that the XN-BF module on Sysmex-9000 may be a suitable alternative to OM for screening BF samples, especially when specific validation rules are used.