Point-of-care testing and INR within-subject variation in patients receiving a constant dose of vitamin K antagonist

2015 ◽  
Vol 114 (12) ◽  
pp. 1260-1267
Author(s):  
Joseph S. Biedermann ◽  
Marieke J. H. A. Kruip ◽  
A. M. H. P. van den Besselaar
Keyword(s):  
Blood Coagulation ◽  
Vitamin K ◽  
Whole Blood ◽  
Point Of Care ◽  
Vitamin K Antagonists ◽  
Professional Staff ◽  
Self Testing ◽  
Target Intensity ◽  
Constant Dose ◽  
Coaguchek Xs

SummaryMany patients treated with vitamin K antagonists (VKA) determine their INR using point-of-care (POC) whole blood coagulation monitors. The primary aim of the present study was to assess the INR within-subject variation in self-testing patients receiving a constant dose of VKA. The second aim of the study was to derive INR imprecision goals for whole blood coagulation monitors. Analytical performance goals for INR measurement can be derived from the average biological within-subject variation. Fifty-six Thrombosis Centres in the Netherlands were invited to select self-testing patients who were receiving a constant dose of either acenocoumarol or phenprocoumon for at least six consecutive INR measurements. In each patient, the coefficient of variation (CV) of INRs was calculated. One Thrombosis Centre selected regular patients being monitored with a POC device by professional staff. Sixteen Dutch Thrombosis Centres provided results for 322 selected patients, all using the CoaguChek XS. The median within-subject CV in patients receiving acenocoumarol (10.2 %) was significantly higher than the median CV in patients receiving phenprocoumon (8.6 %) (p = 0.001). The median CV in low-target intensity acenocoumarol self-testing patients (10.4 %) was similar to the median CV in regular patients monitored by professional staff (10.2 %). Desirable INR analytical imprecision goals for POC monitoring with CoaguChek XS in patients receiving either low-target intensity acenocoumarol or phenprocoumon were 5.1 % and 4.3 %, respectively. The approximate average value for the imprecision of the CoaguChek XS, i. e. 4 %, is in agreement with these goals.

Point-of-care monitoring of vitamin K-antagonists: validation of CoaguChek XS test strips with International Standard thromboplastin

2012 ◽  
Vol 65 (11) ◽  
pp. 1031-1035 ◽  
Author(s):  
Anton M H P van den Besselaar ◽  
Nathalie C V Péquériaux ◽  
Marij Ebben ◽  
Joke van der Feest ◽  
Kerst de Jong ◽  
...  
Keyword(s):  
The Netherlands ◽  
Vitamin K ◽  
Point Of Care ◽  
Vitamin K Antagonists ◽  
Capillary Blood ◽  
Blood Samples ◽  
Test Strips ◽  
International Standard ◽  
The Mean ◽  
Coaguchek Xs

AimsMany patients treated with vitamin K-antagonists (VKA) use point-of-care (POC) whole blood coagulometers for self-testing. The majority of patients in the Netherlands use one type of POC coagulometer, that is, the CoaguChek XS. Each new lot of test strips for the CoaguChek XS is validated by a group of collaborating thrombosis centres. We assessed the International Normalised Ratio (INR) differences between each of 51 new lots of test strips and the International Standard for thromboplastin rTF/95 or its successor rTF/09.MethodsEach year, a particular lot of CoaguChek XS test strips was used as reference lot. The reference lot was validated by comparison to the International Standard, yielding a relationship between the reference lot INR and International Standard INR. Successive lots of test strips were compared to the reference lot by three centres using 19–29 capillary blood samples obtained from VKA-treated patients. Each patient provided two blood drops from the same finger prick, one for the reference lot strip and one for the new lot.ResultsThe mean INR differences between each lot and the International Standard varied between −8% and +4%. The mean absolute values of the relative differences varied between 2.4% and 8.1%. There were small but clinically unimportant differences in INR between the first and second drop of blood.ConclusionsAccuracy of CoaguChek XS INR determinations can be assessed by a group of collaborating centres using a limited number of capillary blood samples. As the mean INR differences with the International Standard were smaller than 10%, the lots were approved for use by the Netherlands Thrombosis Services.

Vitamin K antagonists

ESC CardioMed ◽  
2018 ◽  
pp. 262-264
Author(s):  
Jørgen Jespersen ◽  
Jane Skov
Keyword(s):  
Vitamin K ◽  
Point Of Care ◽  
Vitamin K Antagonists ◽  
International Normalized Ratio ◽  
World Health ◽  
Computer Assisted ◽  
Clinical Settings ◽  
Self Testing ◽  
Clinical Control ◽  
Health Organization

Vitamin K antagonists are widely used for prevention of thrombosis in patients at high risk. Dosage requirements differ greatly among individuals, and interactions are observed with other pharmaceuticals or dietary compounds, necessitating frequent control of the anticoagulant effect. This can be achieved through monitoring of the international normalized ratio. For providing high-quality treatment with vitamin K antagonists, both laboratory and clinical elements must be optimized. The international normalized ratio is measured in the laboratory or by point-of-care devices, in both cases values according to World Health Organization standardization should be reported and external quality assessment established. Clinical control includes measurements of treatment stability for individual patients and the entire clinic. Novel procedures such as computer-assisted dosage and patient self-testing or self-management can improve clinical quality. The vast existing knowledge of vitamin K antagonists and the ongoing research efforts notwithstanding, treatment of optimal quality is still not achieved in all clinical settings and countries.

Abstract 20: Specific Point-of-care Testing of Coagulation in Patients Treated with Non-vitamin K Antagonist Oral Anticoagulants Part I (SPOCT-NOAC I)

Stroke ◽  
2017 ◽  
Vol 48 (suppl_1) ◽  
Author(s):  
Florian J Härtig ◽  
Andreas Peter ◽  
Charlotte Spencer ◽  
Matthias Ebner ◽  
Christine Meyer-Zuern ◽  
...  
Keyword(s):  
Vitamin K ◽  
Whole Blood ◽  
Point Of Care ◽  
Vitamin K Antagonists ◽  
Oral Anticoagulants ◽  
Rapid Assessment ◽  
Plasma Concentrations ◽  
Vitamin K Antagonist ◽  
Point Of Care Testing ◽  
Blood Samples

Introduction: Non-vitamin K antagonist oral anticoagulants (NOAC) are increasingly replacing vitamin K antagonists for prevention of thromboembolism in atrial fibrillation (AF). Despite treatment, stroke rate in NOAC-treated AF-patients remains 1-2% per year. Subsequently, stroke physicians face a growing number of NOAC-treated patients with acute stroke. Rapid assessment of coagulation in NOAC-treated patients is vital prior to thrombolysis or reversal therapy, but existing point-of-care testing (POCT) is suboptimal. For the first time we evaluate NOAC-specific POCT. Hypothesis: Ecarin clotting time (ECT)- and anti-Xa activity (ENOX)-POCT predict plasma concentrations of dabigatran and apixaban/edoxaban/rivaroxaban. Methods: 80 patients receiving first NOAC-dose and 80 already on NOAC-treatment are enrolled in the SPOCT-NOAC I trial (N=40 for each NOAC). Subjects receiving other anticoagulants are excluded. Six blood samples are collected from each patient: before drug intake, 30min, 1, 2, and 8h after intake, and before next dose. NOAC-concentrations are measured by mass spectrometry. Results: 240 blood samples of 40 dabigatran-treated patients were analyzed. Dabigatran-concentrations ranged from 0-274ng/mL. ECT-POCT ranged from 20-196s. Pearson’s correlation coefficient showed strong correlation between ECT-POCT and dabigatran-concentrations (r=0.87). Performance was improved through the use of citrated in place of non-citrated whole blood (r=0.93). Dabigatran-concentrations >50ng/mL (threshold for thrombolysis according to expert recommendation) were detected by ECT-POCT >50s with 98% sensitivity and 79% specificity. Baseline-samples not containing any dabigatran yielded normal ECT values. Conclusions: This is the first study evaluating NOAC-specific POCT. Final results in the dabigatran group of SPOCT-NOAC show excellent correlation between ECT-POCT and dabigatran plasma concentrations; performance of ECT-POCT is even increased through the use of citrated whole blood. Relevant dabigatran-concentrations are detected with excellent sensitivity and specificity. In addition to ECT-POCT, we will present data on ENOX-POCT from apixaban-, edoxaban- and rivaroxaban-treated patients.

Accuracy of the CoaguChek XS for point-of-care international normalized ratio (INR) measurement in children requiring warfarin

2008 ◽  
Vol 99 (06) ◽  
pp. 1097-1103 ◽  
Author(s):  
Karina Black ◽  
Mary Massicotte ◽  
Michelle Bauman ◽  
Stefan Kuhle ◽  
Susan Howlett-Clyne ◽  
...  
Keyword(s):  
Point Of Care ◽  
Vitamin K Antagonists ◽  
Venous Blood ◽  
International Normalized Ratio ◽  
Test Results ◽  
Standard Laboratory ◽  
Limits Of Agreement ◽  
Time Points ◽  
Coaguchek Xs ◽  
Roche Diagnostics

SummaryPoint-of-care INR (POC INR) meters can provide a safe and effective method for monitoring oral vitamin K antagonists (VKAs) in children. Stollery Children’s Hospital has a large POC INR meter loan program for children requiring oral VKAs. Our protocol requires that POC INR results be compared to the standard laboratory INR for each child on several consecutive tests to ensure accuracy of CoaguChek XS® (Roche Diagnostics, Basel Switzerland) meter. It was the objective of the study to determine the accuracy of the CoaguChek XS by comparing whole blood INR results from the CoaguChek XS to plasma INR results from the standard laboratory in children. POC INR meter validations were performed on plasma samples from two time points from 62 children receiving warfarin by drawing a venous blood sample for laboratory prothrombin (PT)-INR measurements and simultaneous INR determinations using the POC-INR meter. Agreement between CoaguChek XS INR and laboratory INR was assessed using Bland-Altman plots. Bland-Altman's 95% limits of agreement were 0.11 (-0.20; 0.42) and 0.13 (-0.22; 0.48) at the two time points, respectively. In conclusion, the CoaguChek XS meter appraisal generates an accurate and precise INR measure in children when compared to laboratory INR test results.

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