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Piacenza F, Galeazzi R, Cardelli M, Moroni F, Provinciali M, Pierpaoli E, Giovagnetti S, Appolloni S, Marchegiani F. Precision and accuracy of the new XPrecia Stride mobile coagulometer. Thromb Res 2017; 156:51-53. [PMID: 28586696 DOI: 10.1016/j.thromres.2017.05.032] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2016] [Revised: 04/26/2017] [Accepted: 05/29/2017] [Indexed: 10/19/2022]
Abstract
INTRODUCTION Oral anticoagulation therapy (OAT) with coumarins (vitamin K antagonist) is the most used against thromboembolism. Prothrombin time (PT) International Normalized Ratio (INR) monitoring is fundamental to establish coumarins dosage and prevent bleeding complications or thrombotic events. In this contest, the method and apparatus used for providing the INR measurements are crucial. Several studies have been published regarding the precision and accuracy of mobile coagulometers with different conclusions. No studies have been published regarding the new XPrecia Stride Mobile Coagulometer (Siemens). The aim of this work is to analyze precision and accuracy of the new XPrecia Stride mobile coagulometer to provide recommendations for clinical use and quality control. MATERIALS AND METHODS A total of 163 patients (mean age=77.4years old) under Warfarin OAT for whom the INR was assessed by both the traditional cs 2100i Sysmex and the new Xprecia Stride Mobile Coagulometer were included in this pilot study. RESULTS AND CONCLUSIONS The precision of the new mobile coagulometer resulted very good (CV<3%). The analytical accuracy was also within the acceptable ranges of reliability (Lin's concordance=0.962). Finally, the clinical accuracy was also acceptable (deviation>15% from the true value in 20% of cases). Considering the overall results obtained by the new Xprecia Stride in comparison to that ones obtained from the other commercial devices, we can conclude that the new coagulometer is enough reliable for clinical settings. However, a larger trial to confirm these data is needed.
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Affiliation(s)
- Francesco Piacenza
- Translational Research Centre of Nutrition and Aging, Scientific and Technological Pole, National Institute of Health and Science on Aging, INRCA-IRCCS, Ancona, Italy.
| | - Roberta Galeazzi
- Clinical Laboratory and Molecular Diagnostics, INRCA-IRCCS, Ancona, Italy
| | - Maurizio Cardelli
- Advanced Technology Center for Aging Research, Scientific and Technological Pole, National Institute of Health and Science on Aging, INRCA-IRCCS, Ancona, Italy
| | - Fausto Moroni
- Clinical Laboratory and Molecular Diagnostics, INRCA-IRCCS, Ancona, Italy
| | - Mauro Provinciali
- Advanced Technology Center for Aging Research, Scientific and Technological Pole, National Institute of Health and Science on Aging, INRCA-IRCCS, Ancona, Italy
| | - Elisa Pierpaoli
- Advanced Technology Center for Aging Research, Scientific and Technological Pole, National Institute of Health and Science on Aging, INRCA-IRCCS, Ancona, Italy
| | - Simona Giovagnetti
- Clinical Laboratory and Molecular Diagnostics, INRCA-IRCCS, Ancona, Italy
| | - Stefania Appolloni
- Clinical Laboratory and Molecular Diagnostics, INRCA-IRCCS, Ancona, Italy
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Johnson SA, Vazquez SR, Fleming R, Lanspa MJ. Correction factor to improve agreement between point-of-care and laboratory International Normalized Ratio values. Am J Health Syst Pharm 2016; 74:e24-e31. [PMID: 28007718 DOI: 10.2146/ajhp150813] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
PURPOSE Results of a research project to quantify and improve the accuracy of point-of-care (POC) International Normalized Ratio (INR) values are reported. METHODS The accuracy of POC INR values relative to laboratory-measured INR values was retrospectively assessed in a cohort of patients with same-day INR determinations by both methods. Univariate linear regression was performed to derive a correction factor for POC INR values of >3; this correction factor was validated in a second cohort. RESULTS In the derivation cohort (259 patients and 344 paired INR results), agreement of POC values with corresponding laboratory INR values at two specified thresholds (±15% and ±25%) was 51.2% and 66.6%, respectively; for POC INR values of >3 (n = 205), agreement was lower (24.9% and 44.9%, respectively). Univariate linear regression yielded a coefficient of 0.77 (95% confidence interval, 0.76-0.79; p < 0.001). Applying a correction factor of 0.8 to POC INR values in a validation cohort (169 patients and 209 paired INR values) significantly improved the accuracy of POC INR values of >3 relative to laboratory values (from 7% to 71.1% at the lower threshold and from 23.5% to 88.8% at the higher threshold, p < 0.0001 for both comparisons). CONCLUSION Agreement between POC and laboratory INR results in one institution was poor, especially when POC INR values exceeded 3. Application of an institution-specific correction factor to POC INR values of >3 improved agreement with laboratory INR results but would not have significantly reduced differences in protocol-based warfarin dosage adjustments.
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Affiliation(s)
- Stacy A Johnson
- University of Utah Health Care Thrombosis Service, Salt Lake City, UT .,Department of Internal Medicine, University of Utah School of Medicine, Salt Lake City, UT.
| | - Sara R Vazquez
- University of Utah Health Care Thrombosis Center, Salt Lake City, UT
| | - Ryan Fleming
- University of Utah Health Care Thrombosis Center, Salt Lake City, UT
| | - Michael J Lanspa
- Division of Pulmonary and Critical Care Medicine, University of Utah and Intermountain Medical Center, Murray, UT
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Comparison of international normalized ratio measurement between CoaguChek XS Plus and STA-R coagulation analyzers. BIOMED RESEARCH INTERNATIONAL 2012; 2013:213109. [PMID: 23509691 PMCID: PMC3591144 DOI: 10.1155/2013/213109] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/22/2012] [Accepted: 10/10/2012] [Indexed: 11/17/2022]
Abstract
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.
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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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Petersen JR, Vonmarensdorf HM, Weiss HL, Elghetany MT. Use of error grid analysis to evaluate acceptability of a point of care prothrombin time meter. Clin Chim Acta 2009; 411:131-4. [PMID: 19913526 DOI: 10.1016/j.cca.2009.11.010] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2009] [Revised: 09/01/2009] [Accepted: 11/09/2009] [Indexed: 11/19/2022]
Abstract
BACKGROUND Statistical methods (linear regression, correlation analysis, etc.) are frequently employed in comparing methods in the central laboratory (CL). Assessing acceptability of point of care testing (POCT) equipment, however, is more difficult because statistically significant biases may not have an impact on clinical care. We showed how error grid (EG) analysis can be used to evaluate POCT PT INR with the CL. MATERIALS AND METHODS We compared results from 103 patients seen in an anti-coagulation clinic that were on Coumadin maintenance therapy using fingerstick samples for POCT (Roche CoaguChek XS and S) and citrated venous blood samples for CL (Stago STAR). To compare clinical acceptability of results we developed an EG with zones A, B, C and D. RESULTS Using 2nd order polynomial equation analysis, POCT results highly correlate with the CL for CoaguChek XS (R(2)=0. 955) and CoaguChek S (R(2)=0. 93), respectively but does not indicate if POCT results are clinically interchangeable with the CL. Using EG it is readily apparent which levels can be considered clinically identical to the CL despite analytical bias. CONCLUSION We have demonstrated the usefulness of EG in determining acceptability of POCT PT INR testing and how it can be used to determine cut-offs where differences in POCT results may impact clinical care.
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Affiliation(s)
- John R Petersen
- University of Texas Medical Branch, Galveston, Texas 77555-0551, United States.
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MADDOX JM, BOGO PH, McGREGOR E, PIPPARD MJ, KERR R. Quality assurance for point-of-care testing of oral anticoagulation: a large-scale evaluation of the Hemochron Junior Signature Microcoagulation System. Int J Lab Hematol 2009; 31:142-50. [DOI: 10.1111/j.1751-553x.2007.01013.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Weinblatt E, Biro D, Chang T, Rand JH, Fox AS. Correlation of the Roche CoaguCheck to Laboratory Plasma International Normalized Ratio at High International Normalized Ratio Values. POINT OF CARE 2009. [DOI: 10.1097/poc.0b013e3181971755] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Park R, Kim YH, Kwon KO, Na J, Won YS, Sung KB, Lee NH, Choi TY, Shin JW, Shin HB, Lee YW, Lee YK. Utility of CoaguChek XS for Monitoring the Prothrombin Time. Tuberc Respir Dis (Seoul) 2008. [DOI: 10.4046/trd.2008.65.6.471] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Affiliation(s)
- Rojin Park
- Department of Laboratory Medicine, Soonchunhyang University Hospital, Seoul, Korea
| | - Yong-Hyun Kim
- Department of Laboratory Medicine and Genetics, Soonchunhyang University Bucheon Hospital, Bucheon, Korea
| | - Kyung Ock Kwon
- Department of Laboratory Medicine and Genetics, Soonchunhyang University Bucheon Hospital, Bucheon, Korea
| | - Jongsung Na
- Department of Laboratory Medicine and Genetics, Soonchunhyang University Bucheon Hospital, Bucheon, Korea
| | - Yong Soon Won
- Department of Thoracic and Cardiovascular Surgery, Soonchunhyang University Bucheon Hospital, Bucheon, Korea
| | - Ki Bum Sung
- Department of Neurology, Soonchunhyang University Bucheon Hospital, Bucheon, Korea
| | - Nae-Hee Lee
- Department of Internal Medicine, Soonchunhyang University Bucheon Hospital, Bucheon, Korea
| | - Tae Youn Choi
- Department of Laboratory Medicine, Soonchunhyang University Hospital, Seoul, Korea
| | - Jeong Won Shin
- Department of Laboratory Medicine, Soonchunhyang University Hospital, Seoul, Korea
| | - Hee Bong Shin
- Department of Laboratory Medicine and Genetics, Soonchunhyang University Bucheon Hospital, Bucheon, Korea
| | - Yong-Wha Lee
- Department of Laboratory Medicine and Genetics, Soonchunhyang University Bucheon Hospital, Bucheon, Korea
| | - You Kyeong Lee
- Department of Laboratory Medicine and Genetics, Soonchunhyang University Bucheon Hospital, Bucheon, Korea
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Lippi G, Salvagno GL, Montagnana M, Manzato F, Guidi GC. Influence of the centrifuge time of primary plasma tubes on routine coagulation testing. Blood Coagul Fibrinolysis 2007; 18:525-8. [PMID: 17581331 DOI: 10.1097/mbc.0b013e3281eec945] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Preparation of blood specimens is a major bottleneck in the laboratory throughput. Reliable strategies for reducing the time required for specimen processing without affecting quality should be acknowledged, especially for laboratories performing stat analyses. The present investigation was planned to establish a minimal suitable centrifuge time for primary samples collected for routine coagulation testing. Five sequential primary vacuum tubes containing 0.109 mol/l buffered trisodium citrate were collected from 10 volunteers and were immediately centrifuged on a conventional centrifuge at 1500 x g, at room temperature for 1, 2, 5, 10 and 15 min, respectively. Hematological and routine coagulation testing, including prothrombin time, activated partial thromboplastin time and fibrinogen, were performed. The centrifugation time was inversely associated with residual blood cell elements in plasma, especially platelets. Statistically significant variations from the reference 15-min centrifuge specimens were observed for fibrinogen in samples centrifuged for 5 min at most and for the activated partial thromboplastin time in samples centrifuged for 2 min at most. Meaningful biases related to the desirable bias were observed for fibrinogen in samples centrifuged for 2 min at most, and for the activated partial thromboplastin time in samples centrifuged for 1 min at most. According to our experimental conditions, a 5-10 min centrifuge time at 1500 x g may be suitable for primary tubes collected for routine coagulation testing.
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Affiliation(s)
- Giuseppe Lippi
- Sezione di Chimica Clinica, Dipartimento di Scienze Morfologico-Biomediche, Università degli Studi di Verona, Ospedale Policlinico G.B.Rossi, Verona, Italy.
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Williams VK, Griffiths AB. Acceptability of CoaguChek S and CoaguChek XS generated international normalised ratios against a laboratory standard in a paediatric setting. Pathology 2007; 39:575-9. [DOI: 10.1080/00313020701684797] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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Hemkens LG, Hilden KM, Hartschen S, Kaiser T, Didjurgeit U, Hansen R, Bender R, Sawicki PT. A randomized trial comparing INR monitoring devices in patients with anticoagulation self-management: evaluation of a novel error-grid approach. J Thromb Thrombolysis 2007; 26:22-30. [PMID: 17965836 DOI: 10.1007/s11239-007-0070-4] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/08/2007] [Accepted: 06/05/2007] [Indexed: 11/25/2022]
Abstract
BACKGROUND In addition to the metrological quality of international normalized ratio (INR) monitoring devices used in patients' self-management of long-term anticoagulation, the effectiveness of self-monitoring with such devices has to be evaluated under real-life conditions with a focus on clinical implications. An approach to evaluate the clinical significance of inaccuracies is the error-grid analysis as already established in self-monitoring of blood glucose. Two anticoagulation monitors were compared in a real-life setting and a novel error-grid instrument for oral anticoagulation has been evaluated. METHODS In a randomized crossover study 16 patients performed self-management of anticoagulation using the INRatio and the CoaguChek S system. Main outcome measures were clinically relevant INR differences according to established criteria and to the error-grid approach. RESULTS A lower rate of clinically relevant disagreements according to Anderson's criteria was found with CoaguChek S than with INRatio without statistical significance (10.77% vs. 12.90%; P = 0.787). Using the error-grid we found principally consistent results: More measurement pairs with discrepancies of no or low clinical relevance were found with CoaguChek S, whereas with INRatio we found more differences with a moderate clinical relevance. A high rate of patients' satisfaction with both of the point of care devices was found with only marginal differences. CONCLUSIONS A principal appropriateness of the investigated point-of-care devices to adequately monitor the INR is shown. The error-grid is useful for comparing monitoring methods with a focus on clinical relevance under real-life conditions beyond assessing the pure metrological quality, but we emphasize that additional trials using this instrument with larger patient populations are needed to detect differences in clinically relevant disagreements.
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Affiliation(s)
- Lars G Hemkens
- DIeM - Institute for Evidence Based Medicine, Venloer Str. 301-303, 50823 Cologne, Germany.
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Hentrich DP, Fritschi J, Müller PR, Wuillemin WA. INR comparison between the CoaguChek® S and a standard laboratory method among patients with self-management of oral anticoagulation. Thromb Res 2007; 119:489-95. [PMID: 16765423 DOI: 10.1016/j.thromres.2006.04.003] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2006] [Revised: 03/21/2006] [Accepted: 04/27/2006] [Indexed: 10/24/2022]
Abstract
INTRODUCTION Portable coagulation monitors have been developed to measure International Normalised Ratio (INR) in orally anticoagulated patients using capillary whole blood from a finger stick. Because of unsatisfactory precision of some of the monitors in comparison with laboratory methods new devices are being developed. In the present study we compared INR determination with the CoaguChek S device with a standard laboratory method among patients with self-management of oral anticoagulation (OAC). METHODS Two hundred and forty-two patients performing self-management of OAC were enrolled into this study. Parallel INR measurements were performed within one hour. Capillary INR measurements (INRcap) were done by the patients with the CoaguChek S and venous INR (INRven) by qualified medical staff using a standard laboratory method. RESULTS We found a correlation coefficient (r(S)) of 0.85 (95% CI: 0.81-0.88) among the 242 patients between INRven and INRcap. In 84.4% of the INR parallel measurements the difference between the two values was below 0.5 INR units. In only 2 of 242 cases the difference was >1 INR unit (1.1 and 1.3). The slope of the Passing Bablok regression line was 0.91 (95% CI: 0.83-1.0) and the y-intercept 0.06 (95% CI: -0.20-0.25). Agreement between both methods was 90.5% (95% CI: 86.8-94.2) and standard-agreement even 97.1% (95% CI: 95-99.2). CONCLUSIONS INR measurement with CoaguChek S device by trained patients revealed reliable results in comparison to the values obtained with a standard laboratory method.
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Affiliation(s)
- Dorota Palka Hentrich
- Division of Hematology and Central Hematology Laboratory, Kantonsspital, Lucerne, 6000 Lucerne 16, Switzerland
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Phillips EM, Buchan DA, Newman N, Rajan A, Zia S. Low-molecular-weight heparin may alter point-of-care assay for international normalized ratio. Pharmacotherapy 2006; 25:1341-7. [PMID: 16185178 DOI: 10.1592/phco.2005.25.10.1341] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
STUDY OBJECTIVE To compare the international normalized ratio (INR) measured by a point-of-care testing device with that measured by a reference laboratory method for patients receiving either warfarin only or warfarin plus low-molecular-weight heparin (LMWH). DESIGN Retrospective study. SETTING Outpatient anticoagulation clinic. SUBJECTS Ninety-one patients receiving warfarin for various indications; 59 of them receiving only warfarin and 32 receiving warfarin plus LMWH. INTERVENTION Capillary blood was obtained for INR determination by a point-of-care device, and venous blood was obtained for INR determination in a standard reference laboratory. MEASUREMENTS AND MAIN RESULTS Ninety-one patients had INR pairs run on a point-of-care device and by the laboratory. In both the patients receiving only warfarin and in those receiving warfarin plus LMWH, the mean INR as determined by the point-of-care testing device was statistically significantly higher than the mean INR determined by the laboratory. Although the differences were statistically significant in both groups, the clinical significance of this difference was accentuated in the patients receiving warfarin plus LMWH. The measure of divergence between the point-of-care and laboratory methods was greater in the group receiving warfarin plus LMWH than in the warfarin-only group, with a mean +/- SD percent change between the INR values of 24.19 +/- 27.54% in the warfarin plus LMWH group and 7.21 +/- 17.73% in the warfarin-only group. In assessing the clinical impact of such variability, a greater degree of discordance in dosing adjustment decisions was noted for patients receiving warfarin plus LMWH. In this group, a 25% rate of discordance was noted compared with 8% in the warfarin-only group. Such discrepancy in dosing decisions based on the point-of-care INR would have resulted in discontinuation of LMWH therapy before the patient acquired a true therapeutic INR, with use of the laboratory measurement. CONCLUSION The INR measured with the point-of-care device in patients receiving concurrent LMWH and warfarin therapy may be inaccurate. Patients receiving LMWH in addition to warfarin should have INRs checked by means of the standard reference laboratory method.
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Affiliation(s)
- Elizabeth M Phillips
- Department of Medicine, State University of New York Upstate Medical University, Syracuse, New York, USA
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Gardiner C, Williams K, Mackie IJ, Machin SJ, Cohen H. Patient self-testing is a reliable and acceptable alternative to laboratory INR monitoring. Br J Haematol 2005; 128:242-7. [PMID: 15638860 DOI: 10.1111/j.1365-2141.2004.05300.x] [Citation(s) in RCA: 79] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
SAn ageing population and the continuing expansion of clinical indications for coumadin therapy have increased pressure on hospital anticoagulant clinics. One solution is patient self-testing (PST) of the international normalized ratio (INR) using capillary blood samples on point-of-care coagulation monitors at home. We conducted a prospective study to determine whether patients can achieve accurate INR values through PST, using the CoaguChek S (Roche Diagnostics, Lewes, UK). The main outcome measurements were: comparability of INR values obtained by PST and the hospital laboratory, patient acceptability as assessed by a questionnaire and anticoagulant control. Eighty-four patients [53 men, 31 women; median age 59 years (range 26-83)], receiving long-term oral anticoagulation (warfarin), were recruited from our Anticoagulation Clinic. Patients were randomized to weekly self-testing or continuing 4-weekly hospital laboratory monitoring of INR. Comparison of INRs (n = 234) showed no significant differences between the CoaguChek (median INR 3.02) and laboratory testing (median INR 3.07). There was excellent correlation between the two methods (r = 0.95), with 85% of CoaguChek results within 0.5 INR units of the laboratory method. On four occasions, differences of >1 unit INR were obtained, but in each case the patient's anticoagulation was unstable (INR >4.5 by both methods) and the differences in INR would not have altered patient management. 87% of patients found self-testing straightforward, 87% were confident in the result they obtained and 77% preferred self-testing. We conclude that PST is a reliable alternative to hospital clinic attendance and is acceptable to the majority of suitably trained patients.
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Affiliation(s)
- Chris Gardiner
- Department of Haematology, University College London Hospitals NHS Trust, London, UK.
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Abstract
PURPOSE OF REVIEW The increasing numbers of patients on oral anticoagulants may challenge the traditional organization of patient monitoring. The availability of portable coagulometers capable of measuring prothrombin time (PT) international normalized ratio (INR) in a drop of capillary blood facilitates decentralization of monitoring by self-testing. This article reviews the literature on use of portable coagulometers. RECENT FINDINGS Numerous studies have evaluated the reliability of portable coagulometers in testing the PT-INR. This has been assessed by statistically as well as clinically relevant criteria. Other studies have been devoted to developing calibration models fulfilling the criteria recommended by the World Health Organization (WHO) for the calibration of INR measuring systems. Finally, studies have assessed the value of schemes for patient training and for the long-term quality assurance of portable coagulometers. SUMMARY It can be concluded from the published studies that PT-INR self-testing may be considered as a suitable alternative to conventional laboratory testing. For the PT-INR to be reliable, manufacturers of portable coagulometers should calibrate their devices against international standards for thromboplastin with procedures similar to those recommended by WHO for conventional measuring systems. Training of patients and implementation of appropriate quality assessment schemes are also essential prerequisites for the success of PT-INR self-testing.
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Affiliation(s)
- Armando Tripodi
- Angelo Bianchi Bonomi Hemophilia and Thrombosis Center, Department of Internal Medicine, University and IRCCS Maggiore Hospital, Via Pace 9, 20122 Milan, Italy.
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