The performance of the ESR parameter of the new Yumizen H500E analyser compared to the reference method (Mechatronics Inversa) and another 'Alternative' ESR measurement analyser (Alifax Test 1)

Introduction

The haematology department of University Hospital in Wales, Cardiff, is a large laboratory that supports both the Hospital (including many specialist units such as renal care, oncology, haematology and rheumatology) outpatient departments, and the surrounding general practitioner community. It therefore has access to samples from a broad range of patient demographics and pathological disorders.

Automated ‘alternative’ methods have been developed which focus on the early stage of the ESR process, the formation of rouleaux. These are faster, require less blood and many have improved precision over the reference method. The International Council of Standardization in Haematology (ICSH) mandates that results should be comparable to Westergren.

The new Yumizen H500E employs an ‘alternative’ optical methodology, incorporated into a routine CBC analyser, which tracks the agglomeration stage of red cells to provide an ESR result in 60 seconds.

Methodology

The analytical performances were assessed according CSLI EP09c - A3 guidelines and included method comparison vs reference method and another alternative method.

The study used residual blood from routine laboratory samples. For correlation studies, where there was sufficient blood, samples were run on a Yumizen H500E OT (HORIBA), a Yumizen H550E, a Test 1 (Alifax), and an Inversa RR (Mechatronics). The use of two different HORIBA instruments enabled a more comprehensive verification of method comparison and also inter-instrument comparison. The Test 1 instrument is in routine use in the laboratory.

The aim was to recruit sufficient samples over as wide as possible range of results.

Samples were also recruited across a wide range of clinical conditions. No exclusions were made on the basis of clinical details but very low haematocrit results <35 were not included in the method comparison with Westergren.

Any aberrant results were further investigated to explore clinical or sample conditions which may explain discrepancies

Instrument Technology

• Inversa RR (Mechatronics)
The Inversa is a semi-automatic Westergren ESR analyzer . Results can be provided after 30 minutes but for the purposes of this study, a 1 hour time was used in accordance with the reference methodology. The system aspirates around 1.4ml EDTA whole blood anticoagulated and dilutes it in the device with sodium citrate (4:1). The carousel contains twenty-four glass Westergren pipettes. The measurement is corrected according to the temperature and the test results are expressed in millimeters/hour.

• Alifax Test-1 (Alifax)
The Alifax ESR analyzers measure red blood cell aggregation. Using 175 μl of EDTA blood sample, the test result is expressed in mm/h. The analysis takes around 20 seconds, and the device has a capacity of 60 samples at a time.

• Yumizen H500E OT/CT and Yumizen H550E (HORIBA)
These are a range of haematology instruments that, in addition to full blood count analysis, are capable of producing an ESR result in 60 seconds from a standard EDTA whole blood sample utilizing an ESR technology called CoRA (Correlated Rouleaux Analysis).

Stage 1 - Aspiration
The transparent aspiration tubing contains diluent, which provides a blank value with each measurement, air to create a barrier and then whole blood. As the blood is aspirated, the shearing forces deform the red cells. This ‘stretching’ slightly reduces the ability of the cells to absorb light.

Stage 2 - Relaxation
The aspiration is stopped, allowing the red cells to relax back to their original shape. This action changes the optical absorption of the sample.

Stage 3 Agglomeration
With the blood sample static, the red cells are allowed to agglomerate over 30 seconds to form rouleaux (stacks or rolls of cells). As the rouleaux form, the interstitial spaces increase allowing an increase in light transmission. During all of these stages an optical measurement is made every 50ms and the transmission changes are tracked, allowing a plot called a syllectogram, to be generated. The data is sent to a specific processing chip which converts the results to an ESR measurement.

Discussion & Conclusion

The validation protocols performed by the laboratory confirmed the acceptable performance of the CoRA technology of the Yumizen H500 and Yumizen H550 analysers. The two analysers demonstrate acceptable correlation with the Westergren methodology, even with higher values and the inter–instrument correlation and K2 vs K3 EDTA comparisons were excellent, providing confidence that the technology can produce highly consistent results.

The correlation with the Test 1 was also acceptable and cross calibration could eliminate any bias. It is worth noting that there were no exclusions made on the basis of clinical condition. The clinical details of the patients were, however, recorded and this facilitated some additional observations regarding performance with specific pathologies, notably post-operative renal patients, patients post bone-marrow transplant, polytrauma, post-natal sepsis. In these patients, marginally higher values were observed. The values were not sufficient to invalidate the method comparison but, taken in isolation, it could suggest that the Yumizen ESR technology could be more sensitive to inflammation in these cases.

More work needs to be performed but this could lead to additional confirmatory signalling or improved outcome monitoring regarding certain conditions. Because alternative methods focus on only one stage and are less influenced by other non-inflammatory factors such as low haematocrit, blood pH, interferences such as hyperbilirubinemia or hyperlipidaemia can be reduced or eliminated. However, the importance of clinical conditions and the specific effect they have on the formation of rouleaux may skew these alternatives.

A combination approach (CBC + ESR) as used by the Yumizen H500E, would allow for a more rapid estimation of non-specific inflammation.

The compact footprint could also allow for a rapid near-care measure of ESR without requiring any secondary analyser capacity.

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The performance of the ESR parameter of the new Yumizen H500E analyser compared to the reference method (Mechatronics Inversa) and another 'Alternative' ESR measurement analyser (ALIFAX TEST 1)

The ESR is one of the most common screening tests worldwide; non-specific but used to detect inflammatory disease. The reference remains the Westergren method, which measures the sedimentation of erythrocytes in whole blood within a standardised tube over 1 hour. The new Yumizen H500E employs an ‘alternative’ optical methodology, incorporated into a routine CBC analyser, which tracks the agglomeration stage of red cells to provide an ESR result in 60 seconds.

The performance of the ESR parameter of the new Yumizen H500E analyser compared to the reference method (Mechatronics Inversa) and another 'Alternative' ESR measurement analyser (Alifax Test 1)

Introduction

Methodology

Instrument Technology

Results

Discussion & Conclusion

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