The Optimum Number and Types of Plasma Samples Necessary for an Accurate Activated Partial Thromboplastin Time–Based Heparin Therapeutic Range

Marlar, Richard A.; Gausman, Jana N.

doi:10.5858/arpa.2011-0516-oa

Cited by 19 publications

(24 citation statements)

References 17 publications

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“…The reason for this is unknown but may relate to the patients included in the analysis as a wider range of 1.6-3.0 has been reported [10]. This reflects the lack of specificity of APTT for heparin effect and it is possible that analysis of a larger number of samples is required, as proposed by some authors [17], although others have suggested that 20 may be sufficient [18]. This reflects the lack of specificity of APTT for heparin effect and it is possible that analysis of a larger number of samples is required, as proposed by some authors [17], although others have suggested that 20 may be sufficient [18].…”

Section: Discussionmentioning

confidence: 99%

Evaluation of the Q analyzer, a new cap-piercing fully automated coagulometer with clotting, chromogenic, and immunoturbidometric capability

Kitchen

Woolley²

2013

Blood Coagulation &Amp; Fibrinolysis

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The Q analyzer is a recently launched fully automated photo-optical analyzer equipped with primary tube cap-piercing and capable of clotting, chromogenic, and immunoturbidometric tests. The purpose of the present study was to evaluate the performance characteristics of the Q analyzer with reagents from the instrument manufacturer. We assessed precision and throughput when performing coagulation screening tests, prothrombin time (PT)/international normalized ratio (INR), activated partial thromboplastin time (APTT), and fibrinogen assay by Clauss assay. We compared results with established reagent instrument combinations in widespread use. Precision of PT/INR and APTT was acceptable as indicated by total precision of around 3%. The time to first result was 3 min for an INR and 5 min for PT/APTT. The system produced 115 completed samples per hour when processing only INRs and 60 samples (120 results) per hour for PT/APTT combined. The sensitivity of the DG-APTT Synth/Q method to mild deficiency of factor VIII (FVIII), IX, and XI was excellent (as indicated by APTTs being prolonged above the upper limit of the reference range). The Q analyzer was associated with high precision, acceptable throughput, and good reliability. When used in combination with DG-PT reagent and manufacturer's instrument-specific international sensitivity index, the INRs obtained were accurate. The Q analyzer with DG-APTT Synth reagent demonstrated good sensitivity to isolated mild deficiency of FVIII, IX, and XI and had the advantage of relative insensitivity to mild FXII deficiency. Taken together, our data indicate that the Q hemostasis analyzer was suitable for routine use in combination with the reagents evaluated.

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Section: Discussionmentioning

confidence: 99%

Evaluation of the Q analyzer, a new cap-piercing fully automated coagulometer with clotting, chromogenic, and immunoturbidometric capability

Kitchen

Woolley²

2013

Blood Coagulation &Amp; Fibrinolysis

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“…The overall assessment of the ex vivo HTR method is that the same laboratory generates an accurate HTR if the same reagent lot and instrumentation methodology are used. Although these studies are not performed on all commercially available reagents or instruments but limited to a selection of the 2-3 different reagents, the same results are found [8,19]. Therefore, the basic findings can be applied to all reagents-instrument systems [8,19].…”

Section: Discussionmentioning

confidence: 82%

“…Both assays are calibrated using the manufacturer's calibrators (assigned against the WHO unfractionated heparin standard). In a comparison study of the two heparin assays, no significant difference in the heparin values is noted between assay kits (r = 0.95, slope = 0.99, P = 0.86) [8,19]. No difference in the heparin levels between unfrozen and frozen samples is found (data not shown).…”

Section: Heparin Antifactor Xa Assaymentioning

confidence: 91%

The effect of instrumentation and laboratory site on the accuracy of the APTT‐based heparin therapeutic range

Marlar

Gausman

2012

Int J Lab Hematology

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Summary Background Monitoring of unfractionated heparin therapy by activated partial thromboplastin time using the ex vivo method for determining the heparin therapeutic range (HTR) is the standard of practice. Many extrinsic and intrinsic factors influence accuracy of the HTR. This study investigates the affect of instrumentation and laboratory site on the accuracy of the ex vivo HTR method. Methods Patients on unfractionated heparin are used to determine the HTR by published guidelines. Various instruments and different laboratories are compared to investigate the affect of these variables on the HTR. Results The HTR is the same when the same model of instrument or even different models (same methodology) are used in the same laboratory. However, a significant clinical difference is observed when different hospital laboratories using same lot and instrument model are compared. Conclusions The ex vivo method for HTR is the best protocol currently available. The HTR should be determined and averaged on all of the same method instruments used in the laboratory. However, determination of the HTR in different laboratories should not be shared.

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“…However, different investigations demonstrated that standardization between laboratories using aPTT for monitoring UFH therapy is quite poor. Each laboratory should determine their aPTT reagent sensitivity to UFH and establish local heparin TI for every new reagent lot, reagent type or instrument which is very complicated in routine ( 11 , 18 , 19 ). …”

Section: Discussionmentioning

confidence: 99%

“…LMWH use has at least partly suppressed many aPTT testing issues in the context of heparin monitoring and replaced UFH as the preferred option in many clinical situations ( 19 ). As expected, survey respondents from Clinical Hospital Centres and Clinical Hospitals declared to use exclusively anti-Xa assay, while smaller hospital laboratories use aPTT for monitoring LMWH therapy.…”

Section: Discussionmentioning

confidence: 99%

Policies and practices in haemostasis testing among laboratories in Croatia: a survey on behalf of a Working Group for Laboratory Coagulation of the Croatian Society of Medical Biochemistry and Laboratory Medicine

Bronić¹,

Herak

Margetić³

et al. 2017

Biochem Med

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IntroductionThe objective of this survey was to assess current policies and practice in haemostasis testing among both hospital and outpatient laboratories in Republic of Croatia.Materials and methodsA questionnaire with seventy questions divided into nine sections was created in May 2015. Participants were asked about their practice related to test request form, sample collection, prothrombin time (PT) and activated partial thromboplastin time assays, other individual haemostasis assays, point-of-care testing (POCT), reporting of coagulation tests results and quality assurance of procedures, the personnel and other laboratory resources, as well as on issues related to education and implementation of additional coagulation assays in their laboratory. The survey was administered and data were collected between June and September 2015.ResultsA total survey response rate was 104/170 (61.2%). Most respondents were faced with incomplete information on prescribed therapy and diagnosis on the test request or inappropriate samples withdrawn on distant locations, but also do not have protocols for handling samples with high haematocrit values. Reporting of PT-INR and D-dimer results was different between laboratories. Although almost all laboratories developed a critical value reporting system, reporting a value to general practitioners is still a problem. Result on coagulation POCT testing showed that not all devices were supervised by laboratories, which is not in compliance with Croatian Chamber of Medical Biochemistry acts.ConclusionObtained results highlighted areas that need improvement and different practice patterns in particular field of haemostasis testing among laboratories. A harmonization of the overall process of haemostasis testing at national level should be considered and undertaken.

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The Optimum Number and Types of Plasma Samples Necessary for an Accurate Activated Partial Thromboplastin Time–Based Heparin Therapeutic Range

Cited by 19 publications

References 17 publications

Evaluation of the Q analyzer, a new cap-piercing fully automated coagulometer with clotting, chromogenic, and immunoturbidometric capability

Evaluation of the Q analyzer, a new cap-piercing fully automated coagulometer with clotting, chromogenic, and immunoturbidometric capability

The effect of instrumentation and laboratory site on the accuracy of the APTT‐based heparin therapeutic range

Policies and practices in haemostasis testing among laboratories in Croatia: a survey on behalf of a Working Group for Laboratory Coagulation of the Croatian Society of Medical Biochemistry and Laboratory Medicine

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