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Bang HI, Lee JY, Kim HY, Shin S, Nam MH, Kim IS, Kim JM, Yoon JH, Shin MG, Hwang SM, Kong SY. Coagulation Testing in Real-World Setting: Insights From a Comprehensive Survey. Clin Appl Thromb Hemost 2024; 30:10760296241228239. [PMID: 38321776 PMCID: PMC10851719 DOI: 10.1177/10760296241228239] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2023] [Revised: 12/18/2023] [Accepted: 01/07/2024] [Indexed: 02/08/2024] Open
Abstract
The objective of this survey was to gain a real-world perspective on coagulation testing by evaluating the availability of various coagulation laboratory tests, assessing specific analytic and postanalytic steps in clinical laboratories in Korea.Participants were surveyed using a 65-question questionnaire specifically focused on their coagulation testing practices related to prothrombin time (PT), activated partial thromboplastin time (aPTT), plasma-mixing studies, lupus anticoagulant (LA) tests, platelet function tests, coagulation factor assays, and the composition of hemostasis and thrombosis test panels. The survey was performed between July and September 2022.The survey achieved a 77.9% (81 of 104) response rate. PT or aPTT tests were performed directly at all participating institutions, followed by D-dimer and fibrinogen tests, platelet function test, and plasma-mixing studies in order of frequency. Variations existed in the performance of mixing test and LA assessment. Patterns of coagulating testing differed depending on the size of the hospital. The survey revealed that most laboratories conducted coagulation tests following the international guidelines such as Clinical Laboratory Standards Institute guidelines and the Korean Laboratory Certification system. However, some coagulation tests, including mixing test and LA tests, are yet to be standardized in Korea.Continuous education on coagulation test methods and internal and external quality control are required to encourage laboratories to enhance the performance of coagulation testing.
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Affiliation(s)
- Hae In Bang
- Department of Laboratory Medicine, Soonchunhyang University Seoul Hospital, Seoul, The Republic of Korea
| | - Ja Young Lee
- Department of Laboratory Medicine, Inje University Busan Paik Hospital, Busan, The Republic of Korea
| | - Hyun-Young Kim
- Department of Laboratory Medicine and Genetics, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, The Republic of Korea
| | - Saeam Shin
- Department of Laboratory Medicine, Yonsei University College of Medicine, Seoul, The Republic of Korea
| | - Myung Hyun Nam
- Department of Laboratory Medicine, Korea University Anam Hospital, Seoul, The Republic of Korea
| | - In-Suk Kim
- Department of Laboratory Medicine, Pusan National University Yangsan Hospital, Yangsan, The Republic of Korea
| | - Ji Myung Kim
- Department of Laboratory Medicine, Chungnam National University College of Medicine, Daejeon, The Republic of Korea
| | - Jong-Hyun Yoon
- Department of Laboratory Medicine, Seoul National University Boramae Medical Center, Seoul, The Republic of Korea
| | - Myung-Geun Shin
- Department of Laboratory Medicine, Chonnam National University Medical School and Chonnam National University Hwasun Hospital, Hwasun, The Republic of Korea
| | - Sang Mee Hwang
- Department of Laboratory Medicine, Seoul National University Bundang Hospital, Seongnam, The Republic of Korea
| | - Sun-Young Kong
- Department of Laboratory Medicine, National Cancer Center Hospital, Goyang, The Republic of Korea
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Chan J, Michaelsen K, Estergreen JK, Sabath DE, Gollakota S. Micro-mechanical blood clot testing using smartphones. Nat Commun 2022; 13:831. [PMID: 35149711 PMCID: PMC8837659 DOI: 10.1038/s41467-022-28499-y] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2021] [Accepted: 01/26/2022] [Indexed: 11/09/2022] Open
Abstract
Frequent prothrombin time (PT) and international normalized ratio (INR) testing is critical for millions of people on lifelong anticoagulation with warfarin. Currently, testing is performed in hospital laboratories or with expensive point-of-care devices limiting the ability to test frequently and affordably. We report a proof-of-concept PT/INR testing system that uses the vibration motor and camera on smartphones to track micro-mechanical movements of a copper particle. The smartphone system computed the PT/INR with inter-class correlation coefficients of 0.963 and 0.966, compared to a clinical-grade coagulation analyzer for 140 plasma samples and demonstrated similar results for 80 whole blood samples using a single drop of blood (10 μl). When tested with 79 blood samples with coagulopathic conditions, the smartphone system demonstrated a correlation of 0.974 for both PT/INR. Given the ubiquity of smartphones in the global setting, this proof-of-concept technology may provide affordable and effective PT and INR testing in low-resource environments. Therapy with anticoagulants requires frequent monitoring. Here the authors describe a proof-of-concept study of a simple and affordable blood clot test that uses a smartphone’s vibration motor and camera to track micro-movements in a single drop of blood.
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Affiliation(s)
- Justin Chan
- Paul G. Allen School of Computer Science and Engineering, University of Washington, Seattle, WA, USA.
| | - Kelly Michaelsen
- Department of Anesthesiology & Pain Medicine, University of Washington, Seattle, WA, USA.
| | - Joanne K Estergreen
- Department of Laboratory Medicine & Pathology, University of Washington, Seattle, WA, USA
| | - Daniel E Sabath
- Department of Laboratory Medicine & Pathology, University of Washington, Seattle, WA, USA
| | - Shyamnath Gollakota
- Paul G. Allen School of Computer Science and Engineering, University of Washington, Seattle, WA, USA.
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Reliability of Point-of-Care International Normalized Ratio Measurements in Various Patient Populations. POINT OF CARE 2020. [DOI: 10.1097/poc.0000000000000197] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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Kim B, Jang S, Lee YJ, Park N, Cho YU, Park CJ. The rivaroxaban-adjusted normalized ratio: use of the prothrombin time to monitor the therapeutic effect of rivaroxaban. Br J Biomed Sci 2019; 76:122-128. [DOI: 10.1080/09674845.2019.1605648] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Affiliation(s)
- B Kim
- Department of Laboratory Medicine, Soonchunhyang University Cheonan Hospital, Soonchunhyang University College of Medicine, Cheonan, Republic of Korea (South Korea)
| | - S Jang
- Department of Laboratory Medicine, University of Ulsan College of Medicine and Asan Medical Center, Seoul, Republic of Korea (South Korea)
- Asan Clinical Research Center, Seoul, Republic of Korea (South Korea)
| | - YJ Lee
- Asan Clinical Research Center, Seoul, Republic of Korea (South Korea)
| | - N Park
- Asan Clinical Research Center, Seoul, Republic of Korea (South Korea)
| | - YU Cho
- Department of Laboratory Medicine, University of Ulsan College of Medicine and Asan Medical Center, Seoul, Republic of Korea (South Korea)
| | - CJ Park
- Department of Laboratory Medicine, University of Ulsan College of Medicine and Asan Medical Center, Seoul, Republic of Korea (South Korea)
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Lee HJ, Kim JE, Lee HY, Lim HS, Kim HK. Significance of local international sensitivity index systems for monitoring warfarin and liver function. Am J Clin Pathol 2014; 141:542-50. [PMID: 24619756 DOI: 10.1309/ajcp2ry1pirrpuow] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022] Open
Abstract
OBJECTIVES Use of a local calibrator has been recommended for standardization of the international normalized ratio (INR) and international sensitivity index (ISI). We investigated the performance of two commercial local calibrators for warfarin monitoring and determined the significance of liver-specific INR. METHODS ISI values were determined using the World Health Organization (WHO) method and two commercial local calibrators. Liver-specific ISI was determined using plasma samples from patients with liver cirrhosis and normal controls. RESULTS In warfarin monitoring, the two local ISIs determined by the two local calibrators showed better consistency than uncorrected ISI, although they were inferior to the ISIs calibrated using the WHO method. Alternative calibration using calibration plasma from patients with liver cirrhosis instead of warfarinized plasma reduced the INR variability. CONCLUSIONS Local ISI determined by a commercial local calibrator improved INR standardization among thromboplastins. The alternative ISI calibration using liver-specific calibration plasma is expected to reduce INR variability for the evaluation of liver function.
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Affiliation(s)
- Hwa Jeen Lee
- Department of Laboratory Medicine, Seoul National University College of Medicine, Seoul, Korea
| | - Ji-Eun Kim
- Cancer Research Institute, Seoul National University College of Medicine, Seoul, Korea
| | - Hye Yeon Lee
- Department of Laboratory Medicine, Seoul National University College of Medicine, Seoul, Korea
| | - Hae Sook Lim
- Department of Laboratory Medicine, Seoul National University College of Medicine, Seoul, Korea
| | - Hyun Kyung Kim
- Department of Laboratory Medicine, Seoul National University College of Medicine, Seoul, Korea
- Cancer Research Institute, Seoul National University College of Medicine, Seoul, Korea
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Use of INR calibrator plasmas in the routine coagulation laboratory: a study of two thrombolastin reagents. Thromb Res 2012; 130:e158-62. [PMID: 22682443 DOI: 10.1016/j.thromres.2012.05.015] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2012] [Revised: 04/29/2012] [Accepted: 05/11/2012] [Indexed: 11/22/2022]
Abstract
INR values may be either calculated with the ISI values supplied by thromboplastin manufacturers or are directly extrapolated from certified INR calibrator plasmas. We tested the principle of local INR calibration using INR calibrator plasmas (PT-Multi Calibrator, Siemens), two thromboplastin reagents (Neoplastin Plus, rabbit brain, Stago, coagulometer-specific ISI 1.31, and Innovin, recombinant human tissue factor, Siemens) and the same coagulometer (STA-R, Stago) in 100 patients on warfarin. Using a ISI value of 0.77 with Tomenson correction for Innovin (correction factor=1.09), INR values of patients were similar with the two reagents, with a bias of 0.03 INR units and no significant regression of the difference over the average INR by method comparison analysis. With the INR calibrator plasmas, INR values with Neoplastin Plus were lower than Innovin values with an average bias of 0.39 INR units and a significant regression of the difference over the average INR (r=-0.91). Significant bias (0.16 INR units, p<0.00001) and regression (r=-0.77) was also observed by comparison of Neoplastin Plus INRs with Innovin calibrated INRs. Based on a therapeutic INR interval of 2.0 to 3.5, discordance in warfarin dosing was approximately 3 times higher with INR calibration (27% vs 11%). Because of non commutability with fresh plasma samples, local INR calibration with lyophilized calibrator plasmas may not be valid for some reagent-instrument combinations.
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Christensen TD, Larsen TB. Precision and accuracy of point-of-care testing coagulometers used for self-testing and self-management of oral anticoagulation therapy. J Thromb Haemost 2012; 10:251-60. [PMID: 22118602 DOI: 10.1111/j.1538-7836.2011.04568.x] [Citation(s) in RCA: 71] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/31/2023]
Abstract
BACKGROUND Oral anticoagulation therapy is monitored by the use of the International Normalized Ratio (INR). Patients who perform self-testing or self-management use a point-of-care testing (POCT) coagulometer (INR monitor) to estimate their INRs. A precondition for a correct dosage of coumarins is a correct INR estimation, and the method and apparatus used for providing the INR measurements are crucial in this context. Several studies have been published regarding the precision and accuracy of these POCT coagulometers, and have led to diverse conclusions. It is difficult and challenging to perform an overview of the literature, owing to the vast amount of papers, with differences in design, statistical analysis, etc. OBJECTIVES The aim of this systematic review was to analyze the current literature, especially regarding the precision and accuracy of the POCT coagulometers, to provide recommendations for clinical use and quality control, and to point out areas for future research. METHODS We included a total of 22 studies, of which four were characterized as high-quality studies. RESULTS The precision of the POCT coagulometers was generally adequate for clinical use. Their performance in terms of accuracy has to be viewed in the context of the inherent inaccuracies of INR measurements. CONCLUSIONS The accuracy of POCT coagulometers seems, in this respect, to be generally acceptable, and they can be used in a clinical setting.
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Affiliation(s)
- T D Christensen
- Department of Cardiothoracic and Vascular Surgery & Institute of Clinical Medicine, Aarhus University Hospital, Aarhus N., Denmark.
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Marlar RA, Gausman JN. Do You Report an Accurate International Normalized Ratio? Find Out Using Local Verification and Calibration. Lab Med 2011. [DOI: 10.1309/lm36lusedxeh0gcv] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
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Poller L, Ibrahim S, Keown M, Pattison A, Jespersen J. The prothrombin time/international normalized ratio (PT/INR) Line: derivation of local INR with commercial thromboplastins and coagulometers--two independent studies. J Thromb Haemost 2011; 9:140-8. [PMID: 20942851 DOI: 10.1111/j.1538-7836.2010.04109.x] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
BACKGROUND The WHO scheme for prothrombin time (PT) standardization has been limited in application, because of its difficulties in implementation, particularly the need for mandatory manual PT testing and for local provision of thromboplastin international reference preparations (IRP). METHODS The value of a new simpler procedure to derive international normalized ratio (INR), the PT/INR Line, based on only five European Concerted Action on Anticoagulation (ECAA) calibrant plasmas certified by experienced centres has been assessed in two independent exercises using a range of commercial thromboplastins and coagulometers. INRs were compared with manual certified values with thromboplastin IRP from expert centres and in the second study also with INRs from local ISI calibrations. RESULTS In the first study with the PT/INR Line, 8.7% deviation from certified INRs was reduced to 1.1% with human reagents, and from 7.0% to 2.6% with rabbit reagents. In the second study, deviation was reduced from 11.2% to 0.4% with human reagents by both local ISI calibration and the PT/INR Line. With rabbit reagents, 10.4% deviation was reduced to 1.1% with both procedures; 4.9% deviation was reduced to 0.5% with bovine/combined reagents with local ISI calibrations and to 2.9% with the PT/INR Line. Mean INR dispersion was reduced with all thromboplastins and automated systems using the PT/INR Line. CONCLUSIONS The procedure using the PT/INR Line provides reliable INR derivation without the need for WHO ISI calibration across the range of locally used commercial thromboplastins and automated PT systems included in two independent international studies.
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Affiliation(s)
- L Poller
- EAA Central Facility, Faculty of Life Sciences, University of Manchester, Manchester, UK.
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Poller L, Ibrahim S, Keown M, Pattison A, Jespersen J. Simplified Method for International Normalized Ratio (INR) Derivation Based on the Prothrombin Time/INR Line: An International Study. Clin Chem 2010; 56:1608-17. [DOI: 10.1373/clinchem.2009.141937] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
BACKGROUND
The need to perform local International Sensitivity Index (ISI) calibrations and in particular the requirement for a manual method for prothrombin time (PT) determination, have proved to be obstacles to application of the WHO scheme for PT standardization.
METHODS
We used international normalized ratio (INR) derived with a set of only 5 European Concerted Action on Anticoagulation (ECAA) lyophilized calibrant plasmas, certified manually by expert centers with reference thromboplastins, to determine a local PT/INR Line. We compared results of an independent set of validation plasmas with INRs from conventional ISI calibrations and with manually certified INRs.
RESULTS
The mean certified INR of 5 lyophilized validation plasmas was 2.41 with human thromboplastin, 2.04 with bovine/combined, and 2.80 with rabbit. With 42 human reagents, the mean observed INR of the validation plasmas was 2.68 (11.2% deviation from certified INR). Deviation was reduced to 0.4% with both local ISI calibration and the PT/INR Line. Eight results based on bovine/combined thromboplastin gave an INR deviation of 4.9%, becoming 0.5% after ISI calibration and 2.4% with the PT/INR Line. Six results with rabbit reagents deviated from certified INR by 2.5%. After ISI calibration, deviation became 1.1%, and with the PT/INR Line, 0.7%. The PT/INR Line gave similar results with both linear and orthogonal regression analysis. The total proportion of validation plasmas giving INR within 10% deviation from certified values was 42.5% with uncorrected INR, which increased to 92.1% with local ISI calibration and 93.2% with the PT/INR Line.
CONCLUSIONS
The PT/INR Line procedure with 5 ECAA calibrant plasmas successfully substitutes for local ISI calibrations in deriving reliable INRs.
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Affiliation(s)
- Leon Poller
- European Action on Anticoagulation (EAA) Central Facility, Faculty of Life Sciences, University of Manchester, Oxford Road, Manchester, UK
| | - Saied Ibrahim
- European Action on Anticoagulation (EAA) Central Facility, Faculty of Life Sciences, University of Manchester, Oxford Road, Manchester, UK
| | - Michelle Keown
- European Action on Anticoagulation (EAA) Central Facility, Faculty of Life Sciences, University of Manchester, Oxford Road, Manchester, UK
| | | | - Jørgen Jespersen
- Department of Clinical Biochemistry, Hospital of South West Denmark, Esbjerg, and Department for Thrombosis Research, Institute of Public Health, University of Southern Denmark, Esbjerg, Denmark
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Favaloro EJ, McVicker W, Hamdam S, Hocker N. Improving the harmonisation of the International Normalized Ratio (INR): time to think outside the box? Clin Chem Lab Med 2010; 48:1079-90. [DOI: 10.1515/cclm.2010.216] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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CHA CH, PARK CJ, KIM DH, KIM MJ, CHO YU, JANG S, CHI HS. Direct international normalized ratio determination using multicalibrators is more responsive than the conventional method for measuring prothrombin time. Int J Lab Hematol 2009; 32:392-7. [DOI: 10.1111/j.1751-553x.2009.01195.x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
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Briggs C, Guthrie D, Hyde K, Mackie I, Parker N, Popek M, Porter N, Stephens C. Guidelines for point-of-care testing: haematology. Br J Haematol 2008; 142:904-15. [DOI: 10.1111/j.1365-2141.2008.07274.x] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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Gardiner C, Kitchen S, Dauer RJ, Kottke-Marchant K, Adcock DM. Recommendations for Evaluation of Coagulation Analyzers. ACTA ACUST UNITED AC 2006; 12:32-8. [PMID: 16513544 DOI: 10.1532/lh96.05031] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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Chantarangkul V, Frontoni R, Gresele P, Oca G, Paniccia R, Pellegrini L, Tripodi A. Usefulness of lyophilized calibration plasmas for International Normalized Ratio determination with the bovine combined thromboplastin (Thrombotest): results of a collaborative study. Blood Coagul Fibrinolysis 2005; 16:157-63. [PMID: 15741805 DOI: 10.1097/01.mbc.0000161571.04883.6c] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
The logical solution to account for the influence of coagulometers on the International Sensitivity Index (ISI) is local calibration with freeze-dried plasmas. However, because of their unpredictable behavior these plasmas must be validated before large-scale implementation. We report on a collaborative exercise designed to evaluate the suitability of a set of such plasmas used with Thrombotest in combination with a coagulometer provided by the manufacturer to be used with that reagent. This was a two-step study. First, one lot of reagent was calibrated against the international standard OBT/79 in two expert laboratories. The calibrated lot was then used as an intermediate standard to calibrate two additional lots of the same reagent in four field laboratories where the ISI was determined for both plasma and native blood. The International Normalized Ratio (INR) for the patient plasmas tested in each laboratory were calculated using two algorithms: the World Health Organization-recommended ISI mode (gold standard), and the simplified calibration plasma mode. In the latter, the INR was derived from the local calibration curve constructed by plotting the certified INR versus local coagulation times obtained with calibration plasmas. The between-algorithm INR differences indicate that this set of calibration plasmas may be employed for local INR calibration of the investigated reagent/instrument combination, especially when plasma is used for INR determination where the average INR (range) difference is 5% (3-13%) or 2% (3-8%) according to whether the INRs to calibration plasmas were assigned by the manufacturer or by the two expert laboratories. A slight but measurable difference of the INR may be predicted [9% (6-20%) or 6% (8-15%)] if this set of calibration plasmas is used for local calibration when native blood is employed for INR determination. Whether this bias is of practical significance is to be determined.
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Affiliation(s)
- Veena Chantarangkul
- Angelo Bianchi Bonomi Hemophilia and Thrombosis Center, Department of Internal Medicine, University and IRCCS Maggiore Hospital, Milano, Italy
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van den Besselaar AMHP, Barrowcliffe TW, Houbouyan-Réveillard LL, Jespersen J, Johnston M, Poller L, Tripodi A. Guidelines on preparation, certification, and use of certified plasmas for ISI calibration and INR determination. J Thromb Haemost 2004; 2:1946-53. [PMID: 15550026 DOI: 10.1111/j.1538-7836.2004.00970.x] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Reliable international normalized ratio (INR) determination depends on accurate values for international sensitivity index (ISI) and mean normal prothrombin time (MNPT). Local ISI calibration can be performed to obtain reliable INR. Alternatively, the laboratory may determine INR directly from a line relating local log(prothrombin time [PT]) to log(INR). This can be done by means of lyophilized or frozen plasmas to which certified values of PT or INR have been assigned. Currently there is one procedure for local calibration with certified plasmas which is a modification of the WHO method of ISI determination. In the other procedure, named 'direct' INR determination, certified plasmas are used to calculate a line relating log(PT) to log(INR). The number of certified plasmas for each procedure depends on the method of preparation and type of plasma. Lyophilization of plasma may induce variable effects on the INR, the magnitude of which depends on the type of thromboplastin used. Consequently, the manufacturer or supplier of certified plasmas must assign the values for different (reference) thromboplastins and validate the procedure for reliable ISI calibration or 'direct' INR determination. Certification of plasmas should be performed by at least three laboratories. Multiple values should be assigned if the differences between thromboplastin systems are greater than 10%. Testing of certified plasmas for ISI calibration may be performed in quadruplicate in the same working session. It is recommended to repeat the measurements on three sessions or days to control day-to-day variation. Testing of certified plasmas for 'direct' INR determination should be performed in at least three sessions or days. Correlation lines for ISI calibration and for 'direct' INR determination should be calculated by means of orthogonal regression. Quality assessment of the INR with certified plasmas should be performed regularly and should be repeated whenever there is a change in reagent batch or in instrument. Discrepant results obtained by users of certified plasmas should be reported to manufacturers or suppliers.
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Affiliation(s)
- A M H P van den Besselaar
- Hemostasis and Thrombosis Research Center, Department of Hematology, Leiden University Medical Center, The Netherlands.
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Affiliation(s)
- L Poller
- The University of Manchester, Manchester, UK.
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Brien WF, Crawford L, Raby A, Richardson H. In-house calibration of the international sensitivity index or calibration curve for determination of the international normalized ratio. Arch Pathol Lab Med 2004; 128:308-12. [PMID: 14987157 DOI: 10.5858/2004-128-308-icotis] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
CONTEXT The international normalized ratio (INR) has been used since 1983 to standardize prothrombin time results for patients on oral anticoagulants. However, significant interlaboratory variations have been noted. Attempts have been made to address these differences with the use of instrument-specific International Sensitivity Index (ISI) values and in-house calibration of ISI values. OBJECTIVE To assess the performance of laboratories using a calibration curve for INR testing. DESIGN Attempts to improve performance of the INR include the use of instrument-specific ISI values, model-specific ISI values, in-house calibration of ISI values, and more recently, the preparation of a calibration curve. Several studies have shown an improvement in performance using these procedures. In this study of licensed laboratories performing routine coagulation testing in the Province of Ontario, Canada, the determination of the INR by a calibration curve was compared with the laboratories' usual method of assessment. These methods were subsequently analyzed by comparing the results to instrument-specific ISI, model-specific ISI, and in-house calibrators. International normalized ratios derived by both methods were analyzed for accuracy and precision. The stability of a calibration curve was also investigated. RESULTS Performance of INR testing has improved with use of a calibration curve or in-house calibrators. CONCLUSION The results confirm that either in-house calibrators or the calibration curve improve performance of INR testing. The calibration curve may be easier to use and appears stable up to 4 months.
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Affiliation(s)
- William F Brien
- University Health Network, Department of Laboratory Hematology, Toronto, Ontario
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19
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van den Besselaar AMHP, Houdijk WPM. Use of Lyophilized Calibrant Plasmas for Simplified International Normalized Ratio Determination with a Human Tissue Factor Thromboplastin Reagent Derived from Cultured Human Cells. Clin Chem 2003; 49:2006-11. [PMID: 14633871 DOI: 10.1373/clinchem.2003.023531] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Abstract
Background: For monitoring of treatment with oral anticoagulants, the clotting time obtained in the prothrombin time (PT) test is transformed to the International Normalized Ratio (INR) with use of a system-specific International Sensitivity Index (ISI). The calibrant plasma procedure (CPP) is an alternative approach to INR calculation based on the use of a set of lyophilized plasmas with assigned INRs.
Methods: With the CPP, a linear relationship is established between log(PT) and log(INR), using orthogonal regression. CPP was validated for Simplastin HTF, a new human tissue factor reagent derived from cultured human cells. CPP precision was assessed as the CV of the slope of the regression line. The accuracy of the CPP was determined by comparing the INR obtained with the CPP with that obtained with the established ISI-based reference method. INRs of the calibrants were assigned by different routes: by manufacturer (consensus labeling) or by use of Simplastin HTF or International Reference Preparations (IRPs; rTF/95 or RBT/90).
Results: The mean CV of the CPP regression slope ranged from 1.0% (Simplastin HTF reagent-specific INR) to 2.4% (INR assigned with rTF/95). INRs calculated with the CPP were similar to those obtained with the reference method, but when the routes for assigning INRs to the calibrant plasmas were compared, the mean difference in INR between CPP and the reference method was smaller with Simplastin HTF reagent-specific values. In several (but not all) cases, this difference was significant (P <0.05, t-test).
Conclusion: CPP can be used for local INR determination, but better precision and accuracy are obtained with reagent-specific INRs compared with INR assignment by consensus labeling or IRP.
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Affiliation(s)
- Anton M H P van den Besselaar
- Haemostasis and Thrombosis Research Center, Department of Haematology, Leiden University Medical Center, Leiden, The Netherlands
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