Evaluation and implementation of the STA R Max® hemostaseology analyzer in the central laboratory of a major hospital
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Babette Hofmann
Abstract
Due to a change of provider at Zentrum für Diagnostik at Klinikum Chemnitz a comprehensive validation of the STA R Max® analyser from Stago was undertaken. Alongside intra-assay and inter-assay determinations, a broad range of comparative measurements using pooled patient plasma were also carried out against the previous routine method (BCS XP from Siemens). Results obtained from routine and emergency sample testing are presented in this publication. Good to very good results were observed which allowed for a swift switchover in systems. Furthermore, user friendliness, reagents, turnaround times (TAT) and general susceptibilities of the new system were evaluated. After various adaptations to the diagnostic process, the transition to routine operation successfully took place.
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Introduction
At the end of 2015 the Zentrum für Diagnostik Chemnitz GmbH changed providers for coagulation diagnostic equipment from Siemens to Stago. An essential part of this process involved the validation of new methods and a comparison of methods for the following parameters: Prothrombin time (PT) (Quick %), international normalized ratio (INR), activated partial thromboplasin time (aPTT), fibrinogen according to Clauss, thrombin time, reptilase, D-dimer, antithrombin, activated protein C resistance (APCR), C1-esterase inhibitor activity, protein C, protein S, F.II, V, VII, VIII, IX, X, XI and XII, F.XIII, von Williebrand factor (vWF) antigen and activity, plasminogen, lupus anticoagulant, anti-Xa activity of low molecular weight heparin (LMWH), UFH, danaparoid and fondaparinux.
For this publication, parameters have been selected that are of interest to basic hemostaseological testing. PT (Quick %), INR, aPTT, fibrinogen according to Clauss, thrombin time, D-dimer, antithrombin, anti-Xa activity for LMWH.
Materials and methods
Materials
Commercial reagents and control materials from the companies Stago, Siemens and Haemochrom, pooled patient plasma and individual patient samples.
Equipment
An optical coagulometer (BCS® XP; Siemens, Erlangen, Germany) and a mechanical coagulometer (STA R Max®, Stago, Paris, France) were compared. The parameters PT (Quick %), INR, aPTT, fibrinogen according to Clauss and thrombin time were measured using the respective methods. Antithrombin and anti-Xa activity LMWH were measured chromogenically, and D-dimers immunologically.
Methods of validation
The following test series were used to determine precision:
Intra-assay precision:
Measurement of 20 parameters each of two QC levels
Measurement of 20 parameters from a total of three pools of patient plasma with average values in the reference and/or pathological ranges of each parameter
Only two pool series were tested for AT
Inter-assay precision:
Measurement of 15 parameters each of two QC levels on consecutive days
Measurement of 12–15 parameters from a total of three pools of patient plasma with average values in the reference and/or pathological ranges of each parameter
No pool data were collected on anti-Xa activity LMWH
The comparison of methods was based on the following test series:
Measurement of pairs of parameters using the old and new methods on 40 patient plasma samples per parameter with a large variance over the reference ranges and/or pathological areas
Results
The data collected for intra- and inter-assay precision with control materials are shown in Tables 1–8 . With one exception (D-dimer Pool 1 and 3), no control and pool sample series produced a coefficient of variation (CV) >10%.
Reagents used for the determination of precision.
| Parameter | Old (Siemens) | New (Stago) |
|---|---|---|
| PT (Quick %)/INR | Innovin® | STA® Neoplastin® CI Plus |
| aPTT | Pathromtin® SL | STA® Cephascreen® |
| Fibrinogen according to Clauss | Multifibren® U | STA® fibrinogen 5 |
| Thrombin time | BC® thrombin | STA® thrombin |
| D-dimer | Innovance® D-dimer | STA® LIATEST® D-Di Plus |
| Antithrombin | Innovance® antithrombin | STA® STACHROM® AT III |
| Anti-Xa activity LMWH | Coamatic® heparin (third-party reagent from Haemochrom) | STA® LQUID ANTI-Xa |
PT – inter-assay and intra-assay precision.
| PT (Quick %) | ||||
|---|---|---|---|---|
| Sample/control | Target value, % | Average, % | SD, % | CV, % |
| Intra-assay precision | ||||
| STA® Quali-Clot I | 93.5 | 91.4 | 1.6 | 1.7 |
| STA® Quali-Clot II | 40.0 | 39.8 | 0.7 | 1.8 |
| Pool 1 | – | 111.8 | 2.7 | 2.4 |
| Pool 2 | – | 52.8 | 0.8 | 1.5 |
| Pool 3 | – | 72.3 | 3.1 | 4.4 |
| Sample | ||||
| Inter-assay precision | ||||
| STA® Quali-Clot I | 93.5 | 94.1 | 3.9 | 4.2 |
| STA® Quali-Clot II | 40.0 | 41.1 | 1.4 | 3.5 |
| Pool 1 | – | 104.0 | 4.7 | 4.5 |
| Pool 2 | – | 81.8 | 2.7 | 3.2 |
| Pool 3 | – | 67.5 | 3.1 | 4.7 |
| Siemens N | 97 | 3.2 | ||
| Siemens P | 35 | 3.0 | ||
aPTT – inter-assay and intra-assay precision.
| aPTT | ||||
|---|---|---|---|---|
| Sample/control | Target value, s | Average, s | SD, s | CV, % |
| Intra-assay precision | ||||
| STA® Quali-Clot I | 30.0 | 29.5 | 0.2 | 0.6 |
| STA® Quali-Clot II | 46.5 | 44.5 | 0.3 | 0.6 |
| Pool 1 | – | 27.5 | 0.3 | 0.9 |
| Pool 2 | – | 94.8 | 1.4 | 1.5 |
| Pool 3 | – | 33.9 | 0.4 | 1.0 |
| Sample | ||||
| Inter-assay precision | ||||
| STA® Quali-Clot I | 30.0 | 30.7 | 0.5 | 1.5 |
| STA® Quali-Clot II | 46.5 | 45.0 | 0.5 | 1.1 |
| Pool 1 | – | 28.9 | 0.3 | 0.9 |
| Pool 2 | – | 34.2 | 0.3 | 0.9 |
| Pool 3 | – | 39.7 | 0.6 | 1.6 |
| Siemens N | 32.2 | 1.8 | ||
| Siemens P | 93.0 | 2.2 | ||
Fibrinogen according to Clauss – inter-assay and intra-assay precision.
| Fibrinogen according to Clauss | ||||
|---|---|---|---|---|
| Sample/control | Target value, g/L | Average, g/L | SD, g/L | CV, % |
| Intra-assay precision | ||||
| STA® Quali-Clot I | 2.9 | 2.7 | 0.05 | 1.7 |
| STA® Quali-Clot II | 1.2 | 1.1 | 0.02 | 1.8 |
| Pool 1 | – | 3.4 | 0.06 | 1.6 |
| Pool 2 | – | 1.3 | 0.03 | 2.1 |
| Pool 3 | – | 5.6 | 0.07 | 1.2 |
| Sample | ||||
| Inter-assay precision | ||||
| STA® Quali-Clot I | 2.9 | 2.7 | 0.09 | 3.4 |
| STA® Quali-Clot II | 1.2 | 1.1 | 0.04 | 3.1 |
| Pool 1 | – | 3.9 | 0.17 | 4.3 |
| Pool 2 | – | 4.4 | 0.14 | 3.1 |
| Pool 3 | – | 2.8 | 0.06 | 2.3 |
| Siemens N | 2.6 | 3.8 | ||
| Siemens P | 0.9 | 5.3 | ||
Thrombin time – inter-assay and intra-assay precision.
| Thrombin time | ||||
|---|---|---|---|---|
| Sample/control | Target value, s | Average, s | SD, s | CV, % |
| Intra-assay precision | ||||
| STA® Quali-Clot I | 17.0 | 16.8 | 0.2 | 0.9 |
| STA® Quali-Clot III | 34.5 | 34.2 | 0.7 | 2.1 |
| Pool 1 | – | 15.9 | 0.2 | 1.1 |
| Pool 2 | – | 15.3 | 0.2 | 1.2 |
| Pool 3 | – | 34.2 | 2.4 | 1.9 |
| Sample | ||||
| Inter-assay precision | ||||
| STA® Quali-Clot I | 17.0 | 17.0 | 0.1 | 1.1 |
| STA® Quali-Clot III | 34.5 | 34.1 | 0.6 | 1.6 |
| Pool 1 | – | 16.7 | 0.4 | 2.3 |
| Pool 2 | – | 19.8 | 0.7 | 3.4 |
| Pool 3 | – | 18.0 | 0.4 | 2.0 |
| Siemens N | 20.6 | 4.7 | ||
| Siemens P | 37.3 | 7.1 | ||
D-dimer – inter-assay and intra-assay precision.
| D-dimer | ||||
|---|---|---|---|---|
| Sample/control | Target value, μg/mL | Average, μg/mL | SD, μg/mL | CV, % |
| Intra-assay precision | ||||
| STA® D-Di Control 1 | 0.85 | 0.80 | 0.03 | 4.2 |
| STA® D-Di Control 2 | 2.35 | 2.24 | 0.04 | 2.0 |
| Pool 1 | – | 0.33 | 0.08 | 22.9 |
| Pool 2 | – | 2.80 | 0.09 | 3.4 |
| Pool 3 | – | 0.73 | 0.07 | 10.1 |
| Sample | ||||
| Inter-assay precision | ||||
| STA® D-Di Control 1 | 0.85 | 0.87 | 0.06 | 7.0 |
| STA® D-Di Control 2 | 2.35 | 2.35 | 0.22 | 9.2 |
| Pool 1 | – | 0.93 | 0.06 | 6.8 |
| Pool 2 | – | 2.80 | 0.09 | 3.4 |
| Pool 3 | – | 3.50 | 0.15 | 4.4 |
| Innovance D-DIM 1 | 0.34 | 5.7 | ||
| Innovance D-DIM 2 | 2.72 | 3.5 | ||
Antithrombin – inter-assay and intra-assay precision.
| Antithrombin | ||||
|---|---|---|---|---|
| Sample/control | Target value, % | Average, % | SD, % | CV, % |
| Intra-assay precision | ||||
| STA® Quali-Clot I | 100.5 | 96.3 | 1.6 | 1.7 |
| STA® Quali-Clot II | 40.0 | 38.9 | 1.8 | 4.7 |
| Pool 1 | – | 60.6 | 1.0 | 1.6 |
| Pool 2 | – | 98.4 | 1.5 | 1.6 |
| Sample | ||||
| Inter-assay precision | ||||
| STA® Quali-Clot I | 100.5 | 100.1 | 4.5 | 4.5 |
| STA® Quali-Clot II | 40.0 | 40.3 | 2.9 | 7.2 |
| Pool 1 | – | 98.0 | 3.4 | 3.5 |
| Pool 2 | – | 95.8 | 4.0 | 4.1 |
| Pool 3 | – | 58.2 | 3.4 | 5.9 |
| Siemens N | 100 | 3.9 | ||
| Siemens P | 36 | 5.7 | ||
Anti-Xa activity – inter-assay and intra-assay precision.
| Anti-Xa activity NMH | ||||
|---|---|---|---|---|
| Sample/control | Target value, IU/mL | Average, IU/mL | SD, IU/mL | CV, % |
| Intra-assay precision | ||||
| STA® HBPM/LMWH 1 | 0.90 | 0.93 | 0.04 | 3.9 |
| STA® HBPM/LMWH 2 | 1.65 | 1.64 | 0.04 | 2.5 |
| Pool 1 | – | 4.38 | 0.16 | 3.6 |
| Pool 2 | – | 1.00 | 0.02 | 2.2 |
| Pool 3 | – | 0.27 | 0.27 | 2.8 |
| Sample | ||||
| Inter-assay precision | ||||
| STA® HBPM/LMWH 1 | 0.90 | 0.92 | 0.03 | 3.4 |
| STA® HBPM/LMWH 2 | 1.65 | 1.72 | 0.09 | 5.2 |
| Technoview LMH L | 0.3 | 12.1 | ||
| Technoview LMH M | 0.64 | 9.23 | ||
| Technoview LMH H | 1.3 | 4.86 | ||
The data collected as part of the comparison of methods are shown in Figures 1–8. Fundamentally different measurement methods and reagent properties did not give rise to an expectation of ideal linear correlations. The correlation coefficients (range from 0.60 to 0.90), with the exception of PT (0.94) and D-dimer (0.97).
Correlation of PT on STA R Max and BCS XP.
The respective reference ranges are shown as dashed lines.
Correlation of INR on STA R Max and BCS XP.
Correlation of aPTT on STA R Max and BCS XP.
The respective reference ranges are shown as dashed lines.
Correlation of fibrinogen according to Clauss on STA R Max and BCS XP.
The respective reference ranges are shown as dashed lines.
Correlation of thrombin time on STA R Max and BCS XP.
The respective reference ranges are shown as dashed lines.
Correlation of D-dimer on STA R Max and BCS XP.
The cut-off limits are shown as dashed lines.
Correlation of antithrombin on STA R Max and BCS XP.
The respective reference ranges are shown as dashed lines.
Correlation of anti-Xa LMWH on STA R Max and BCS XP.
Inter- and intra-assay precision
Three pool series each of varying concentrations were included in the validation of the D-dimer test alongside two quality controls. The QC targets were at 0.85 and/or 2.35 μg/mL; the corresponding CV of intra-assay precision at 4.2 and/or 2.0%. In two of the three pool series, the average concentration was at 0.33 and/or 0.73 μg/mL and, thus, below the QC targets. These series produced a CV of 22.9% and/or 10.1%. The company Stago indicates a limit of quantitation (LoQ) of 0.27 μg/mL. The suitability of the pool series with the average concentration of 0.33 μg/mL must be put into question. As for the third pool series with an average concentration of 2.8 μg/mL, the CV was 3.4%.
Discussion
Previous coagulation diagnostics by means of the BCS® XP from Siemens were based on photometry. With the change to Stago as provider, mechanical coagulometry (VBDS) becomes the basis of analysis. The methodology of the viscosity-based detection system (VBDS) is significantly less susceptible to interference by lipemia and icterus. Detailed studies on the influence of hemolysis, icterus and lipemia were published by Wooley et al. [1]. The cap-piercing method saves an extra working step, and in large laboratories with a high throughput, it substantially supports process optimization [2]. The higher dead volumes resulting from the application of cap piercing occur where special analytics are provided and where the care of premature and newborn babies must be ensured, taken into account and addressed through appropriate measures. We managed to implement a solution for this issue at our laboratory by conducting open measurements on one (STA Compact Max®) out of a total of three (2 STA R Max®, 1 STA Compact Max®) devices available. Stago may require somewhat longer reconstitution times (e.g. AT: Siemens ready for use, Stago 60 min and reptilase: Siemens ready for use, Stago 30 min). This can be integrated well into everyday routine thanks to experiential time management. The reagents crucial to the routine are pre-calibrated in a user-friendly manner, such as for determining PT (Quick %), INR, fibrinogen according to Clauss and D-dimer. Pre-calibration reduces the users’ hands-on time and allows for a standardized application. Like the associated controls, the D-dimer reagent is available in liquid form, ready for use, and the STA analyzer facilitates very short measuring times. Fibrinogen is also determined by means of a liquid reagent. The advantage of these liquid reagents lies in easy handling and high-grade standardization, as well as long-lasting stability, even when on board. These advantages are relativized in part by greater expenditure in the overall process.
F.XIII, APCR and vWF activity can be measured with external reagents. A proposed application for STA R Max®, validated by Stago, is available to analyze vWF activity on the basis of external reagents.
The measurement method of the new STA R Max® and STA Compact Max® analyzers allows for reliable analyses. The numerous liquid and ready-to-use reagents, as well as the pre-calibration of essential parameters offer a high degree of standardization and shorter hands-on time.
Intra- and inter-assay precisions, measured with control materials, are at least comparable to the previous routine method. It must be noted, however, that the Guideline of the German Medical Association on Quality Assurance in Medical Laboratory Examinations (RiliBÄK), as amended [3], only contains provisions on the relative square measurement deviation of aPTT (10.5%).
The reference ranges specified by the manufacturer were tested on healthy, adult subjects. As for premature and newborn babies, it was necessary to draw on the method-specific information contained in the literature, because there were only some reagent-specific limits, and because it was impossible to obtain them through our own patient material [4], [5], [6], [7], [8].
For this publication, parameters were selected from the entire validated spectrum that are significant in basic diagnostics and, therefore, are of great interest. These include PT (Quick %), INR and aPTT as so-called global parameters, fibrinogen as a key parameter in the care of polytraumatized patients and emergency cases of hemorrhaging, D-dimer as the pillar of cardiopulmonary differential diagnostics and DIC diagnostics, antithrombin, in addition to aPTT, to control unfractionated heparin (UFH) therapy as well as thrombin time and anti-Xa activity for LMWH, which allow for a remaining concentration of direct-acting oral anticoagulants (DOACs) in the blood to be ruled out and/or detected.
Comparison of methods
Reagents for the determination of PT (Quick %), INR and aPTT of various manufacturers, as is well known, exhibit different sensitivities to factor deficiencies, lupus anticoagulants and heparin, depending on their content of phospholipids and activators. As a result, manufacturers generally recommend that users conduct comparative measurements on materials from their own patient populations in order to determine reference and/or therapeutic target ranges. But this approach is very complex and feasible in the necessary scope only to a limited extent, which is why the ranges obtained from manufacturers or the literature should be verified – at a minimum, by random checks – on one’s own patient population. As for our comparison of methods, the correlation coefficients, in connection with the intercept and slope, yielded acceptable readings for almost all parameters (see Figures 1–8).
The change in the measurement system should be pointed out to submitters due to the correlation coefficients of 0.94 for PT and 0.91 for INR. Here, too, it became clear that INR cannot be used to achieve a full standardization of the measured values.
The influence of intravenously applied UFH on the results of the comparative measurement must be emphasized for aPTT. The reduced heparin sensitivity of the aPTT reagent from the company Stago requires a definition of new therapeutic target ranges based on experience. In case of doubt, and if insufficient aPTT control is presumed, we refer to the UFH-calibrated determination of anti-Xa activity. However, the cited target range is not method- or reagent-specific [9], [10].
For fibrinogen according to Clauss, D-dimer (immunoturbidimetric test) and anti-Xa activity for LMWH, the results correlate well.
Metrologically speaking, a 1:40 dilution occurred for values >140% on the STA R Max during the validation phase in accordance with the antithrombin test configuration. There was no dilution with the Siemens test method. The comparative measurements of antithrombin revealed a wider variance in the upper reference range (≥120%). Under scientific consensus, elevated antithrombin levels are not clinically relevant. The dilution step on the machine is therefore unnecessary.
The variance of the comparative measured values of thrombin time cannot be explained conclusively. The reagent from the company Stago contains 1.5 IU/mL thrombin; the reagent from Siemens, 1.0 IU/mL. These different concentrations are not offset entirely by the mixing ratios of sample and reagent in the assays. Despite identical reference ranges for both tests (adults: 19–21 s), the Stago reagent tends to measure shorter thrombin times, as opposed to the Siemens reagent. The differentiation between pathological and normal remained unaffected in 37 or 40 value pairs. Differences were found for three samples for which the Siemens test produced a value just above the upper reference range limit, while a measured value within the reference range was obtained with the Stago reagent. These samples did not contain any dabigatran.
Author contributions: All the authors have accepted responsibility for the entire content of this submitted manuscript and approved submission.
Research funding: None declared.
Employment or leadership: None declared.
Honorarium: None declared.
Competing interests: The funding organization(s) played no role in the study design; in the collection, analysis, and interpretation of data; in the writing of the report; or in the decision to submit the report for publication.
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Article note:
The original version in German is available at: http://www.degruyter.com/view/j/labm.2017.41.issue-2/labmed-2016-0089/labmed-2016-0089.xml. The German article was translated by Compuscript Ltd. and authorized by the authors.
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