Multicentre ISI assignment and calibration of the INR measuring range of a new point-of-care system designed for home monitoring of oral anticoagulation therapy

2007 ◽  
Vol 97 (05) ◽  
pp. 586-861 ◽  
Author(s):  
Ingrid Leichsenring ◽  
Winfried Plesch ◽  
Volker Unkrig ◽  
Steve Kitchen ◽  
Dianne Kitchen ◽  
...  
Keyword(s):  
Polynomial Regression ◽  
Point Of Care ◽  
Anticoagulation Therapy ◽  
Coagulation Cascade ◽  
Sensitivity Index ◽  
Normal Donor ◽  
Who Guidelines ◽  
Measuring Range ◽  
The Mean ◽  
Coaguchek Xs

SummaryThe new CoaguChek XS system is designed for use in patient selftesting. It is the successor of the current CoaguChek S system. The detection principle is based on the amperometric measurement of the thrombin activity initiated by starting the coagulation cascade using a human recombinant thromboplastin. This study was performed to assign the International SEnsitivity Index (ISI) to the new test according to the WHO guidelines for thromboplastins and plasmas used to control anticoagulant therapy, and to establish the measuring range of the new system. At four study sites a total of 90 samples of normal donors and 291 samples of warfarin-, phenprocoumon- or acenocoumarol-treated patients were included in the study.The ISI value of the new test was assigned against the human recombinant reference thromboplastin rTF/95 at each site using the samples from stabilized patients in the International Normalized Ratio (INR) range between 1.5 and 4.5 only. The new point-of-care system’s measuring range between 0.8 and 8 INR was calibrated against the mean INR of rTF/95 and AD149 using polynomial regression. ISIs were (CV of the slope): Site 1: ISI 0.99 (1.1%); Site 2: ISI 1.02 (2.0%); Site 3: ISI 1.03 (1.1%); Site 4: ISI 1.00 (1.4%). All regression lines calculated from patient-only data pass through the normal donor data points.All CVs of the slopes of the orthogonal regression lines are well below 3%,thus fulfilling the requirements of the WHO guidelines. The mean ISI for the new CoaguChek XS PT Test is 1.01.

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.

The Reliability of Point-of-Care (POC) Prothrombin Time Testing - A Comparison of CoaguChek XS® INR Measurements with Hospital Laboratory Monitoring.

Blood ◽  
2007 ◽  
Vol 110 (11) ◽  
pp. 973-973 ◽  
Author(s):  
Fiona Ryan ◽  
Susan O’Shea ◽  
Thomas L. Ortel ◽  
Stephen Byrne
Keyword(s):  
Clinical Laboratory ◽  
Point Of Care ◽  
Venous Blood ◽  
Anticoagulation Therapy ◽  
University Hospital ◽  
External Quality ◽  
Hospital Laboratory ◽  
Laboratory Values ◽  
Venous Sample ◽  
Coaguchek Xs

Abstract Background The development of Point of Care (POC) testing devices enables patients to test their own International Normalised Ratio (INR) at home, and has lead to the development of patient self- testing (PST) programmes. This facilitates more frequent testing of anticoagulation levels which in turn improves time in therapeutic range (TTR) and reduces bleeding and thrombotic complications in patients on oral anticoagulation therapy (OAT).1 External quality control of POC devices is essential to ensure that results are robust. One approach is to collect a venous sample at the same time as POC testing, which is analysed using an appropriate hospital laboratory analyzer. It has been recommended that INR results should be within 0.5 of each other when measured by each method2. However, previous studies have shown that when compared with clinical laboratory values, POC devices may show statistically significant differences between the INR values.3 Aim The aim of this study is primarily to compare TTR and adverse events between two different approaches to OAT management and more specifically in this presentation to examine the intra patient variability of INR measurements performed by two different techniques. Methods 160 patients routinely attending the anticoagulant clinic of Cork University Hospital (CUH) were enrolled to take part in a prospective randomized controlled, cross-over design trial of supervised PST of warfarin therapy using an internet based expert system (Coagcare®, ZyCare, Inc) and POC testing device (CoaguChek XS®, Roche, UK) vs. rountine medical care in CUH. During the 6 months PST arm of the study a venous blood sample was taken from each patient for laboratory determination of the INR on 3 occasions; at enrolment, 2 months and 4 months. This measurement was then compared with the INR measured on the Coaguchek XS® machine using capillary blood from the patient’s fingertip. Results 88 patients have being enrolled in the PST arm of the study to date and 454 POC measurements have been compared with laboratory values. Good correlation has been shown between the two methods of INR determination (r2 = 0.8314), however, statistically significant differences did occur (p < 0.005). A Bland and Altman plot showed good agreement between the dual measurements at values between 2.0–3.5 INR units. However there seemed to be increasing disagreement between the two methods as the INR rose above 3.5. Four patients were excluded from the study because the differences in the INR measurements were greater than 0.5 INR units. Conclusion POC testing devices for OAT are reliable and safe. External quality assessment should be inherent to any programme involving these devices. Clinicians involved in the use of POC anticoagulation monitoring should be aware that POC and laboratory values may differ and intervene if there is not adequate correlation between the two INR measurements.

scholarly journals Assessment of the CoaguChek-XS portable prothrombin time point-of-care analyzer for horses

2019 ◽  
Vol 31 (3) ◽  
pp. 448-452 ◽  
Author(s):  
Noa Berlin ◽  
Efrat Kelmer ◽  
Gilad Segev ◽  
Itamar Aroch ◽  
Gal Kelmer
Keyword(s):  
Prothrombin Time ◽  
High Precision ◽  
Point Of Care ◽  
Reference Interval ◽  
Life Threatening ◽  
The Mean ◽  
Preliminary Study ◽  
Coaguchek Xs ◽  
Roche Diagnostics ◽  
Good Agreement

Coagulopathies in horses are common and potentially life-threatening. In equine field medicine, a portable point-of-care (POC) prothrombin time (PT) testing device could be useful to identify early changes in extrinsic clotting. The CoaguChek-XS (Roche Diagnostics) is a small, portable POC PT analyzer used in human medicine. Our preliminary study assessed the suitability of CoaguChek-XS for testing PT in horses and established the PT reference interval (PT RI) in healthy horses using this instrument. Blood samples collected from 102 healthy and ill horses were analyzed with the CoaguChek-XS and compared to a semi-automated coagulometric analyzer (SACA) as the gold standard. There was a significant positive correlation between the 2 measurement methods ( r = 0.765, p < 0.01), and very good agreement, with 97% of the samples falling within limits of agreement. The mean CoaguChek-XS PT coefficient of variation was 0.8%, indicating high precision. With high precision and good agreement with the coagulometric PT, the CoaguChek-XS should be further validated for PT measurement in horses.

Point-of-care monitoring of oral anticoagulation therapy in children

2009 ◽  
Vol 102 (07) ◽  
pp. 159-165 ◽  
Author(s):  
Anthea Greenway ◽  
Robyn Summerhayes ◽  
Fiona Newall ◽  
Janet Burgess ◽  
Lydia DeRosa ◽  
...  
Keyword(s):  
Prothrombin Time ◽  
Oral Anticoagulation ◽  
Gold Standard ◽  
Clinical Decision Making ◽  
Point Of Care ◽  
Anticoagulation Therapy ◽  
Clinical Decision ◽  
Gold Standard Reference ◽  
Coaguchek Xs ◽  
The Impact

SummaryPoint-of-care (POC) monitoring of oral anticoagulation has been widely adopted in both paediatric and adult patients. A new POC system, the CoaguChek XS® has recently been developed to measure the international normalised ratio (INR) and may offer significant advantages. The CoaguChek XS® utilises a new method of electrochemical clot detection based on thrombin generation. This system has not been previously evaluated in children with reference to the laboratory gold standard, the prothrombin time using reference thromboplastin. It was the objective to compare values obtained by the CoaguChek XS® system with both the venous INR and the gold standard for anticoagulant monitoring, prothrombin time with reference thromboplastin (rTF/95).To evaluate the impact of testing using the Coagu-Chek XS® on clinical anticoagulant dosing decisions. Fifty paired venous INR and capillary CoaguChek XS® results were obtained from 31 children (aged up to 16 years).The laboratory gold standard, a manual prothrombin time with reference thromboplastin (rTF/95) was additionally performed on 26 samples. Correlation between the CoaguChek XS® result and the venous INR was r= 0.810. Agreement between the CoaguChek XS result and the reference INR was shown to be higher (r=0.95), in the subset analysed by this method. Correlation between the venous INR and reference INR was r=0.90. Despite changes to the methodology of testing with the CoaguChek XS® POC monitoring system, the accuracy of this method when compared with both the venous INR and gold standard reference INR was satisfactory. This resulted in infrequent changes to clinical decision making regarding anticoagulation

scholarly journals Prospective Comparison of Point-of-Care Device and Standard Analyzer for Monitoring of International Normalized Ratio in Outpatient Oral Anticoagulant Clinic

2018 ◽  
Vol 24 (7) ◽  
pp. 1153-1158 ◽  
Author(s):  
Bushra Moiz ◽  
Anila Rashid ◽  
Muhammad Hasan ◽  
Lena Jafri ◽  
Ahmed Raheem
Keyword(s):  
Point Of Care ◽  
Hospital Setting ◽  
International Normalized Ratio ◽  
Mean Difference ◽  
Altman Plot ◽  
Prospective Comparison ◽  
Self Testing ◽  
The Mean ◽  
Coaguchek Xs ◽  
Laboratory Analyzer

Point-of-care testing (POCT) coagulometers are increasingly being used in the hospital setting and patients’ self-testing. We determined the agreement of prothrombin time international normalized ratio (INR) results by POCT coagulometer and laboratory instrument through a comparative analysis and investigated whether the results of POCT coagulometer can reliably be used without being confirmed by standard laboratory analyzer. A total of 200 INR measurements by POCT coagulometer (CoaguChek XS Pro) and laboratory analyzer (Sysmex CS2000i) were compared using Passing-Bablok regression analysis and Bland-Altman plot. Agreement of the INR measurement was further analyzed in relation to dosing decision. The correlation of INR measurements between CoaguChek XS Pro and Sysmex CS2000i was excellent (correlation coefficient = 0.973). The overall mean difference was 0.21 INR ± 0.32 (range: 1.7-0.44). The mean difference was found to get increased as INR results increased and was 0.09 in the subtherapeutic range (≤1.9 INR), 0.29 INR in the therapeutic range (2.0-3.0 INR), while 0.4 INR in the supratherapeutic range (>3.0 INR). The overall agreement was excellent (κ = 0.916) and overall 11 (5.5%) of 200 INR measurements showed a difference in dosing decision between the 2 instruments. The positive bias of POC-INR is evident in the supratherapeutic range which could affect the dosing decision requiring confirmation with the laboratory INR measurement.

scholarly journals Comparison of International Normalized Ratio Measurement between CoaguChek XS Plus and STA-R Coagulation Analyzers

2013 ◽  
Vol 2013 ◽  
pp. 1-6 ◽  
Author(s):  
Mina Hur ◽  
Hanah Kim ◽  
Chul Min Park ◽  
Antonio La Gioia ◽  
Sang-Gyu Choi ◽  
...  
Keyword(s):  
Point Of Care ◽  
Hospital Setting ◽  
International Normalized Ratio ◽  
Excellent Correlation ◽  
Point Of Care Testing ◽  
Altman Plot ◽  
Ratio Measurement ◽  
The Mean ◽  
Coaguchek Xs ◽  
Roche Diagnostics

Background. Point-of-care testing (POCT) coagulometers are increasingly being used in the hospital setting. We investigated whether the prothrombin time international normalized ratio (INR) results by CoaguChek XS Plus (Roche Diagnostics GmbH, Mannheim, Germany) can be used reliably without being confirmed with the INR results by STA-R system (Diagnostica Stago S.A.S, Asnières sur Seine, France).Methods. A total of 118 INR measurements by CoaguChek XS Plus and STA-R were compared using Passing/Bablok regression analysis and Bland-Altman plot. Agreement of the INR measurements was further assessed in relation to dosing decision.Results. The correlation of INR measurements between CoaguChek XS Plus and STA-R was excellent (correlation coefficient = 0.964). The mean difference tended to increase as INR results increased and was 0.25 INR in the therapeutic range (2.0-3.0 INR). The overall agreement was fair to good (kappa = 0.679), and 21/118 (17.8%) INR measurements showed a difference in dosing decision.Conclusion. The positive bias of CoaguChek XS Plus may be obvious even in the therapeutic INR range, and dosing decision based on the CoaguChek XS Plus INR results would be different from that based on the STA-R results. The INR measurements by POCT coagulometers still need to be confirmed with the laboratory INR measurements.

scholarly journals European Concerted Action on Anticoagulation. Evaluation of a Method for International Sensitivity Index Calibration of Two Point-of-Care Prothrombin Time (PT) Monitoring Systems (CoaguChek Mini and TAS PT-NC) with Fresh Plasmas Based on Whole-Blood Equivalent PT

2002 ◽  
Vol 48 (10) ◽  
pp. 1672-1680 ◽  
Author(s):  
Leon Poller ◽  
Michelle Keown ◽  
Nikhil Chauhan ◽  
Anton MHP van den Besselaar ◽  
Armando Tripodi ◽  
...  
Keyword(s):  
Prothrombin Time ◽  
Whole Blood ◽  
Point Of Care ◽  
Monitoring Systems ◽  
Sensitivity Index ◽  
Test Strips ◽  
Fresh Plasma ◽  
The Mean ◽  
The Difference ◽  
International Sensitivity Index

Abstract Background: The International Sensitivity Index (ISI) calibration of whole-blood prothrombin time (PT) monitors for point-of-care testing (POCT) described by Tripodi et al. (Thromb Haemost 1993;70:921–4) has been shown to be dependable but is too complex and demanding. The use of plasma would simplify calibration of whole-blood POCT PT monitors, but important differences may exist between the ISI for whole blood and plasma calibrations. Methods: In a 10-center calibration study of two POCT whole-blood monitoring systems (CoaguChek Mini and TAS PT-NC), we characterized the relationship between the log PT for whole blood and fresh plasma with use of single lots of test strips/cards. This relationship (linear) was used to correct the difference between the whole-blood and plasma ISI. The reliability of the correction with different lots of test strips/cards was assessed at three centers. The linear relationship was used to correct the difference in the whole-blood and plasma ISI with four other lots of TAS PT-NC cards and with two additional lots of CoaguChek Mini test strips. Results: The correction decreased the ISI difference from 13.3% to 0.9% for the TAS PT-NC and from 5.7% to 0.6% for the CoaguChek Mini. In assessments at three centers, which included different lots of test strips/cards, the mean ISI difference was markedly decreased with the TAS PT-NC but not with the CoaguChek Mini, for which the mean ISI difference increased slightly. Conclusions: The proposed correction resolves the discrepancy between whole-blood and fresh plasma ISI calibrations with TAS PT-NC test cards. The CoaguChek Mini systems could be calibrated without this correction.

scholarly journals European Concerted Action on Anticoagulation. Use of Plasma Samples to Derive International Sensitivity Index for Whole-Blood Prothrombin Time Monitors

2002 ◽  
Vol 48 (2) ◽  
pp. 255-260 ◽  
Author(s):  
Leon Poller ◽  
Michelle Keown ◽  
Nikhil Chauhan ◽  
Anton MHP van den Besselaar ◽  
Joyce Meeuwisse-Braun ◽  
...  
Keyword(s):  
Prothrombin Time ◽  
Whole Blood ◽  
Point Of Care ◽  
Chloride Concentration ◽  
Calibration Procedure ◽  
Sensitivity Index ◽  
Plasma Samples ◽  
Concerted Action ◽  
The Mean ◽  
International Sensitivity Index

Abstract Background: To simplify International Sensitivity Index (ISI) calibration, the possibility of substituting fresh plasma for fresh whole-blood samples with point-of-care testing (POCT) whole-blood monitors was investigated in a three-center study of three different POCT systems. Methods: A modified full WHO calibration procedure based on 20 healthy controls and 60 coumarin-treated patients was performed on three monitoring systems with whole-blood and plasma samples against plasma tested using the European Concerted Action on Anticoagulation (ECAA) rabbit reference plain thromboplastin and the manual prothrombin time (PT) method. Results: With one of the three systems, the mean ISI was 1.51 for whole blood and 1.49 for plasma; with the second system, the mean ISI was 1.08 for both whole blood and plasma. With the third system, however, the difference between the mean ISI for whole blood and that for plasma was greater (1.15 and 1.01, respectively). Overall, the precision of the calibrations was less than with traditional manual plasma PT testing. Conclusions: Provided that an appropriate calcium chloride concentration is used, the plasma PT results can be used for accurate ISI calibration of two of these three whole-blood POCT systems. Precision criteria need to be modified for POCT monitors.

Multi-Center Calibration of the Second Reference Material for Thromboplastin, Rabbit, Plain, Coded CRM 149R

1991 ◽  
Vol 65 (03) ◽  
pp. 263-267 ◽  
Author(s):  
A M H P van den Besselaar ◽  
R M Bertina
Keyword(s):  
Reference Material ◽  
Standard Error ◽  
Standard Errors ◽  
Sensitivity Index ◽  
Long Term Stability ◽  
Significant Bias ◽  
The Mean ◽  
The Relationship ◽  
International Sensitivity Index

SummaryIn a collaborative trial of eleven laboratories which was performed mainly within the framework of the European Community Bureau of Reference (BCR), a second reference material for thromboplastin, rabbit, plain, was calibrated against its predecessor RBT/79. This second reference material (coded CRM 149R) has a mean International Sensitivity Index (ISI) of 1.343 with a standard error of the mean of 0.035. The standard error of the ISI was determined by combination of the standard errors of the ISI of RBT/79 and the slope of the calibration line in this trial.The BCR reference material for thromboplastin, human, plain (coded BCT/099) was also included in this trial for assessment of the long-term stability of the relationship with RBT/79. The results indicated that this relationship has not changed over a period of 8 years. The interlaboratory variation of the slope of the relationship between CRM 149R and RBT/79 was significantly lower than the variation of the slope of the relationship between BCT/099 and RBT/79. In addition to the manual technique, a semi-automatic coagulometer according to Schnitger & Gross was used to determine prothrombin times with CRM 149R. The mean ISI of CRM 149R was not affected by replacement of the manual technique by this particular coagulometer.Two lyophilized plasmas were included in this trial. The mean slope of relationship between RBT/79 and CRM 149R based on the two lyophilized plasmas was the same as the corresponding slope based on fresh plasmas. Tlowever, the mean slope of relationship between RBT/79 and BCT/099 based on the two lyophilized plasmas was 4.9% higher than the mean slope based on fresh plasmas. Thus, the use of these lyophilized plasmas induced a small but significant bias in the slope of relationship between these thromboplastins of different species.

Multi-Center Study of Thromboplastin Calibration Precision – Influence of Reagent Species, Composition, and International Sensitivity Index (ISI)

1993 ◽  
Vol 69 (01) ◽  
pp. 035-040 ◽  
Author(s):  
A M H P van den Besselaar ◽  
R M Bertina
Keyword(s):  
Oral Anticoagulants ◽  
International Normalized Ratio ◽  
The Other ◽  
World Health ◽  
Rabbit Brain ◽  
Sensitivity Index ◽  
Bovine Plasma ◽  
Significant Difference ◽  
The Mean ◽  
International Sensitivity Index

SummaryFour thromboplastin reagents were tested by 18 laboratories in Europe, North-America, and Australasia, according to a detailed protocol. One thromboplastin was the International Reference Preparation for ox brain thromboplastin combined with adsorbed bovine plasma (coded OBT/79), and the second was a certified reference material for rabbit brain thromboplastin, plain (coded CRM 149R). The other two thromboplastin reagents were another rabbit plain brain thromboplastin (RP) with a lower ISI than CRM 149R and a rabbit brain thromboplastin combined with adsorbed bovine plasma (RC). Calibration of the latter two reagents was performed according to methods recommended by the World Health Organization (W. H. O.).The purpose of this study was to answer the following questions: 1) Is the calibration of the RC reagent more precise against the bovine/combined (OBT/79) than against the rabbit/plain reagent (CRM 149R)? 2) Is the precision of calibration influenced by the magnitude of the International Sensitivity Index (ISI)?The lowest inter-laboratory variation of ISI was observed in the calibration of the rabbit/plain reagent (RP) against the other rabbit/plain reagent (CRM 149R) (CV 1.6%). The highest interlaboratory variation was obtained in the calibration of rabbit/plain (RP) against bovine/combined (OBT/79) (CV 5.1%). In the calibration of the rabbit/combined (RC) reagent, there was no difference in precision between OBT/79 (CV 4.3%) and CRM 149R (CV 4.2%). Furthermore, there was no significant difference in the precision of the ISI of RC obtained with CRM 149R (ISI = 1.343) and the rabbit/plain (RP) reagent with ISI = 1.14. In conclusion, the calibration of RC could be performed with similar precision with either OBT/79 or CRM 149R, or RP.The mean ISI values calculated with OBT/79 and CRM 149R were practically identical, indicating that there is no bias in the ISI of these reference preparations and that these reference preparations have been stable since their original calibration studies in 1979 and 1987, respectively.International Normalized Ratio (INR) equivalents were calculated for a lyophilized control plasma derived from patients treated with oral anticoagulants. There were small but significant differences in the mean INR equivalents between the bovine and rabbit thromboplastins. There were no differences in the interlaboratory variation of the INR equivalents, when the four thromboplastins were compared.

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