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Abstract
Point-of-care-testing (POCT) is performance of a laboratory assay outside the laboratory by nontrained personnel. The advantages of POCT are: more rapid medical decisions, avoidance of long sample transports, and small samples. The disadvantages of POCT are: no laboratory personnel, insufficient calibration, quality control and maintenance, poor documentation, high costs, difficult comparability POCT/central laboratory. Therefore, disposing of a 24-hour central laboratory, the POCT spectrum should be limited to the vital parameters: K+, Ca++, Na+, glucose, creatinine, blood gases, hemoglobin or hematocrit, NH3, lactate. POCT offers no advantages, if the hospital has a rapid transport system such as a pneumatic delivery to the central laboratory. The rapid diagnosis of the acute hemostasis state of a patient should be performed in the 24-hour central laboratory that is connected to all hospital wards via a good pneumatic delivery.
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Affiliation(s)
- Thomas W Stief
- Department of Clinical Chemistry, Philipps-University Hospital, Marburg, Germany.
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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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3
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Ageno W, Gallus AS, Wittkowsky A, Crowther M, Hylek EM, Palareti G. Oral anticoagulant therapy: Antithrombotic Therapy and Prevention of Thrombosis, 9th ed: American College of Chest Physicians Evidence-Based Clinical Practice Guidelines. Chest 2012; 141:e44S-e88S. [PMID: 22315269 PMCID: PMC3278051 DOI: 10.1378/chest.11-2292] [Citation(s) in RCA: 1026] [Impact Index Per Article: 85.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/31/2011] [Indexed: 12/11/2022] Open
Abstract
BACKGROUND The objective of this article is to summarize the published literature concerning the pharmacokinetics and pharmacodynamics of oral anticoagulant drugs that are currently available for clinical use and other aspects related to their management. METHODS We carried out a standard review of published articles focusing on the laboratory and clinical characteristics of the vitamin K antagonists; the direct thrombin inhibitor, dabigatran etexilate; and the direct factor Xa inhibitor, rivaroxaban RESULTS The antithrombotic effect of each oral anticoagulant drug, the interactions, and the monitoring of anticoagulation intensity are described in detail and discussed without providing specific recommendations. Moreover, we describe and discuss the clinical applications and optimal dosages of oral anticoagulant therapies, practical issues related to their initiation and monitoring, adverse events such as bleeding and other potential side effects, and available strategies for reversal. CONCLUSIONS There is a large amount of evidence on laboratory and clinical characteristics of vitamin K antagonists. A growing body of evidence is becoming available on the first new oral anticoagulant drugs available for clinical use, dabigatran and rivaroxaban.
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Affiliation(s)
| | | | | | - Mark Crowther
- McMaster University, St. Joseph's Hospital, Hamilton, ON, Canada
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Tripodi A, Chantarangkul V, Primignani M, Dell'Era A, Clerici M, Iannuzzi F, Aghemo A, Cazzaniga M, Salerno F, Mannucci PM. Point-of-care coagulation monitors calibrated for the international normalized ratio for cirrhosis (INRliver) can help to implement the INRliver for the calculation of the MELD score. J Hepatol 2009; 51:288-95. [PMID: 19501423 DOI: 10.1016/j.jhep.2009.04.014] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/04/2009] [Accepted: 04/06/2009] [Indexed: 12/28/2022]
Abstract
BACKGROUND/AIMS The MELD defines a score used to prioritize patients awaiting liver transplantation and includes results for bilirubin, creatinine and PT expressed as INR. It is assumed that the MELD for individual patients is the same regardless of the laboratory method used for testing, thus ensuring parity of organ allocation. Previous studies showed that the INR calibrated for patients on vitamin K antagonists (INR(vka)) does not normalize results across thromboplastins, whereas an alternative calibration called INR(liver) does. However, implementation of INR(liver) calibration for thromboplastins is difficult in practice. This study aimed to assess whether easy-to-run whole-blood coagulation monitors (widely used for patients on VKA) can be calibrated to measure efficiently the INR(liver) and minimize the interlaboratory variability. METHODS PT values for 61 cirrhotic patients were measured on native-blood with 2 monitors calibrated in terms of INR(vka). PTs for these subjects were also measured with a WHO-standard for thromboplastin. Paired-PTs with the monitors and the standard were subsequently used to calibrate the monitors in terms of INR(liver). INR(vka) and INR(liver) were then compared to assess for statistical significance. RESULTS The mean INR(vka) obtained with the monitors and the standard were significantly different (p<0.001). Conversely, the corresponding INR(liver) were not. CONCLUSIONS The INR(liver) calibration as previously described for thromboplastins works also for the easy-to-run whole-blood coagulation monitors. Once the monitors are calibrated by the manufacturer in terms of INR(liver) they could be used as near-patient-testing devices directly by the personnel of liver units making the determination of the INR for patients awaiting liver transplantation much easier and standardized.
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Affiliation(s)
- Armando Tripodi
- Angelo Bianchi Bonomi Hemophilia and Thrombosis Center, Department of Internal Medicine and Medical Specialties, University and IRCCS Ospedale Maggiore, Mangiagalli and Regina Elena Foundation, Via Pace 9, 20122 Milan, Italy.
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Ansell J, Hirsh J, Hylek E, Jacobson A, Crowther M, Palareti G. Pharmacology and management of the vitamin K antagonists: American College of Chest Physicians Evidence-Based Clinical Practice Guidelines (8th Edition). Chest 2008; 133:160S-198S. [PMID: 18574265 DOI: 10.1378/chest.08-0670] [Citation(s) in RCA: 1448] [Impact Index Per Article: 90.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
This article concerning the pharmacokinetics and pharmacodynamics of vitamin K antagonists (VKAs) is part of the American College of Chest Physicians Evidence-Based Clinical Practice Guidelines (8th Edition). It describes the antithrombotic effect of the VKAs, the monitoring of anticoagulation intensity, and the clinical applications of VKA therapy and provides specific management recommendations. Grade 1 recommendations are strong and indicate that the benefits do or do not outweigh the risks, burdens, and costs. Grade 2 recommendations suggest that the individual patient's values may lead to different choices. (For a full understanding of the grading, see the "Grades of Recommendation" chapter by Guyatt et al, CHEST 2008; 133:123S-131S.) Among the key recommendations in this article are the following: for dosing of VKAs, we recommend the initiation of oral anticoagulation therapy, with doses between 5 mg and 10 mg for the first 1 or 2 days for most individuals, with subsequent dosing based on the international normalized ratio (INR) response (Grade 1B); we suggest against pharmacogenetic-based dosing until randomized data indicate that it is beneficial (Grade 2C); and in elderly and other patient subgroups who are debilitated or malnourished, we recommend a starting dose of < or = 5 mg (Grade 1C). The article also includes several specific recommendations for the management of patients with nontherapeutic INRs, with INRs above the therapeutic range, and with bleeding whether the INR is therapeutic or elevated. For the use of vitamin K to reverse a mildly elevated INR, we recommend oral rather than subcutaneous administration (Grade 1A). For patients with life-threatening bleeding or intracranial hemorrhage, we recommend the use of prothrombin complex concentrates or recombinant factor VIIa to immediately reverse the INR (Grade 1C). For most patients who have a lupus inhibitor, we recommend a therapeutic target INR of 2.5 (range, 2.0 to 3.0) [Grade 1A]. We recommend that physicians who manage oral anticoagulation therapy do so in a systematic and coordinated fashion, incorporating patient education, systematic INR testing, tracking, follow-up, and good patient communication of results and dose adjustments [Grade 1B]. In patients who are suitably selected and trained, patient self-testing or patient self-management of dosing are effective alternative treatment models that result in improved quality of anticoagulation management, with greater time in the therapeutic range and fewer adverse events. Patient self-monitoring or self-management, however, is a choice made by patients and physicians that depends on many factors. We suggest that such therapeutic management be implemented where suitable (Grade 2B).
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Affiliation(s)
- Jack Ansell
- From Boston University School of Medicine, Boston, MA.
| | - Jack Hirsh
- Hamilton Civic Hospitals, Henderson Research Centre, Hamilton, ON, Canada
| | - Elaine Hylek
- Boston University School of Medicine, Boston, MA
| | | | - Mark Crowther
- McMaster University, St. Joseph's Hospital, Hamilton, ON, Canada
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Ansell J, Hirsh J, Hylek E, Jacobson A, Crowther M, Palareti G. Pharmacology and Management of the Vitamin K Antagonists. Chest 2008. [DOI: 10.1378/chest.08-0670 order by 1-- gadu] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/09/2023] Open
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Ansell J, Hirsh J, Hylek E, Jacobson A, Crowther M, Palareti G. Pharmacology and Management of the Vitamin K Antagonists. Chest 2008. [DOI: 10.1378/chest.08-0670 and 1880=1880] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/09/2023] Open
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Ansell J, Hirsh J, Hylek E, Jacobson A, Crowther M, Palareti G. Pharmacology and Management of the Vitamin K Antagonists. Chest 2008. [DOI: 10.1378/chest.08-0670 order by 1-- #] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/09/2023] Open
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Ansell J, Hirsh J, Hylek E, Jacobson A, Crowther M, Palareti G. Pharmacology and Management of the Vitamin K Antagonists. Chest 2008. [DOI: 10.1378/chest.08-0670 order by 8029-- awyx] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/09/2023] Open
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Ansell J, Hirsh J, Hylek E, Jacobson A, Crowther M, Palareti G. Pharmacology and Management of the Vitamin K Antagonists. Chest 2008. [DOI: 10.1378/chest.08-0670 order by 1-- -] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/09/2023] Open
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Ansell J, Hirsh J, Hylek E, Jacobson A, Crowther M, Palareti G. Pharmacology and Management of the Vitamin K Antagonists. Chest 2008. [DOI: 10.1378/chest.08-0670 order by 8029-- #] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/09/2023] Open
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Ansell J, Hirsh J, Hylek E, Jacobson A, Crowther M, Palareti G. Pharmacology and Management of the Vitamin K Antagonists. Chest 2008. [DOI: 10.1378/chest.08-0670 order by 8029-- -] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/09/2023] Open
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Newall F, Bauman M. Point-of-care antithrombotic monitoring in children. Thromb Res 2006; 118:113-21. [PMID: 16709480 DOI: 10.1016/j.thromres.2005.03.008] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2005] [Revised: 01/27/2005] [Accepted: 03/18/2005] [Indexed: 11/25/2022]
Abstract
INTRODUCTION The use of oral anticoagulant therapy is increasing in children. Managing anticoagulant therapy in children presents unique challenges, including poor venous access. The advent of point-of-care (POC) monitoring of anticoagulant therapy offers a potential solution to this challenge. This paper reviews the published literature relating to POC monitoring of oral anticoagulant therapy in children. MATERIALS AND METHODS A Medline search was conducted and identified key publications. Papers were reviewed with respect to their objectives, populations and POC device investigated. Study limitations were identified. RESULTS Five publications and one abstract were identified, reporting studies using five different POC monitors. Three studies had a strong clinical management focus. Outcome measures assessed included target therapeutic range achievement and frequency of adverse events. Correlation between POC and laboratory-based results ranged from 0.83 to 0.96. Home monitoring and self-management using POC monitors were both reported to be preferred compared to standard laboratory testing. CONCLUSIONS POC monitoring of oral anticoagulant therapy in children offers considerable advantages. The reviewed literature would suggest such monitoring can be performed accurately and reliably. The impact of quality control issues, such as calibration of thromboplastin ISI in POC devices, has not been explored in a paediatric population. Further studies are needed to clarify such issues and confirm the safety, reliability and efficacy of POC monitoring of oral anticoagulant therapy in children, including its home monitoring and self-management programs.
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Affiliation(s)
- Fiona Newall
- Department of Clinical Haematology, Royal Children's Hospital, Melbourne, Flemington Rd., Parkville 3052, Australia.
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Poller L, Keown M, Chauhan N, van den Besselaar AMHP, Tripodi A, Shiach C, Jespersen J. European Concerted Action on Anticoagulation. A multicentre calibration study of WHO international reference preparations for thromboplastin, rabbit (RBT/90) and human (rTF/95). J Clin Pathol 2005; 58:667-9. [PMID: 15917425 PMCID: PMC1770687 DOI: 10.1136/jcp.2004.019810] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/29/2004] [Indexed: 11/03/2022]
Abstract
A 10 centre calibration was performed after six years to determine the international sensitivity index (ISI) of rTF/95 relative to RBT/90, and to assess any international normalised ratio (INR) bias compared with the original multicentre calibration. After exclusion of one outlying centre, the follow up calibration gave a mean ISI for rTF/95 of 0.99, which although a small difference, is significantly greater than the mean ISI of 0.94 obtained previously. The change in ISI for international reference preparation (IRP) rTF/95 relative to RBT/90 would lead to a slight bias in INR for human compared with rabbit thromboplastins. At a theoretical INR of 3.0, the INR bias is 6.0%, and this is below the accepted 10% level of clinical relevance. Ongoing stability monitoring of World Health Organisation thromboplastin IRP is advised.
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Affiliation(s)
- L Poller
- ECAA Central Facility, Faculty of Life Sciences, University of Manchester, Manchester M13 9PT, UK.
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Ansell J, Hirsh J, Poller L, Bussey H, Jacobson A, Hylek E. The pharmacology and management of the vitamin K antagonists: the Seventh ACCP Conference on Antithrombotic and Thrombolytic Therapy. Chest 2004; 126:204S-233S. [PMID: 15383473 DOI: 10.1378/chest.126.3_suppl.204s] [Citation(s) in RCA: 756] [Impact Index Per Article: 37.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
This article concerning the pharmacokinetics and pharmacodynamics of vitamin K antagonists (VKAs) is part of the Seventh American College of Chest Physicians Conference on Antithrombotic and Thrombolytic Therapy: Evidence-Based Guidelines. The article describes the antithrombotic effect of VKAs, the monitoring of anticoagulation intensity, the clinical applications of VKA therapy, and the optimal therapeutic range of VKAs, and provides specific management recommendations. Grade 1 recommendations are strong, and indicate that the benefits do, or do not, outweigh the risks, burdens, and costs. Grade 2 suggests that individual patient's values may lead to different choices (for a full understanding of the grading see Guyatt et al, CHEST 2004; 126:179S-187S). Among the key recommendations in this article are the following: for dosing of VKAs, we suggest the initiation of oral anticoagulation therapy with doses between 5 and 10 mg for the first 1 or 2 days for most individuals, with subsequent dosing based on the international normalized ratio (INR) response (Grade 2B). In the elderly and in other patient subgroups with an elevated bleeding risk, we suggest a starting dose at < or = 5 mg (Grade 2C). We recommend basing subsequent doses after the initial two or three doses on the results of INR monitoring (Grade 1C). The article also includes several specific recommendations for the management of patients with INRs above the therapeutic range and for patients requiring invasive procedures. For example, in patients with mild to moderately elevated INRs without major bleeding, we suggest that when vitamin K is to be given it be administered orally rather than subcutaneously (Grade 1A). For the management of patients with a low risk of thromboembolism, we suggest stopping warfarin therapy approximately 4 days before they undergo surgery (Grade 2C). For patients with a high risk of thromboembolism, we suggest stopping warfarin therapy approximately 4 days before surgery, to allow the INR to return to normal, and beginning therapy with full-dose unfractionated heparin or full-dose low-molecular-weight heparin as the INR falls (Grade 2C). In patients undergoing dental procedures, we suggest the use of tranexamic acid mouthwash (Grade 2B) or epsilon amino caproic acid mouthwash without interrupting anticoagulant therapy (Grade 2B) if there is a concern for local bleeding. For most patients who have a lupus inhibitor, we suggest a therapeutic target INR of 2.5 (range, 2.0 to 3.0) [Grade 2B]. In patients with recurrent thromboembolic events with a therapeutic INR or other additional risk factors, we suggest a target INR of 3.0 (range, 2.5 to 3.5) [Grade 2C]. As models of anticoagulation monitoring and management, we recommend that clinicians incorporate patient education, systematic INR testing, tracking, and follow-up, and good communication with patients concerning results and dosing decisions (Grade 1C+).
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Affiliation(s)
- Jack Ansell
- Department of Medicine, Boston University Medical Center, 88 E Newton St, Boston, MA 02118, USA.
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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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Poller L, Keown M, Chauhan N, van den Besselaar AMHP, Tripodi A, Shiach C, Jespersen J. European Concerted Action on Anticoagulation. Quality Assessment of the CoaguChek Mini and TAS PT-NC Point-of-Care Whole-Blood Prothrombin Time Monitors. Clin Chem 2004; 50:537-44. [PMID: 14709449 DOI: 10.1373/clinchem.2003.019653] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Abstract
Background: International Normalized Ratios (INRs) for prothrombin time obtained with the CoaguChek Mini and TAS (RapidPointCoag) PT-NC systems are markedly different and also differ from the “true” INR. There is therefore a need for local quality assessment (QA) of the two systems.
Methods: A set of 60 lyophilized artificially depleted and 60 lyophilized coumarin plasmas were tested at 10 centers on both point-of-care testing monitors. Subsets of three and five plasmas were selected as QA plasmas and compared with the remaining 55 to assess the relative ability of the systems to characterize performance at the individual centers. The incidence of aberrant results (outliers; >15% deviation from the true INR) was also recorded. The expected incidence with the QA plasmas was calculated and compared.
Results: On both systems, INR with the common sets of 55 lyophilized plasmas varied considerably between centers. With the TAS PT-NC, subsets of five and three European Concerted Action on Anticoagulation (ECAA) artificially depleted plasmas gave good correlation with the 55 plasmas, but the coumarin plasmas performed less well. With the CoaguChek Mini, correlation was good with sets of five artificially depleted QA plasmas and reasonable with three but was less satisfactory with the coumarin plasmas. Outliers were detected with both types of plasmas on both test systems but with variable success.
Conclusions: With the TAS PT-NC, three ECAA artificially depleted lyophilized plasmas provided reliable QA, but five lyophilized coumarin plasmas were required. With the CoaguChek Mini, five artificially depleted plasmas gave reliable QA but coumarin plasmas gave poorer results. ECAA QA plasmas provide a local system for checking INRs obtained with monitors of both types.
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Affiliation(s)
- Leon Poller
- European Concerted Action on Anticoagulation Central Facility, School of Biological Sciences, The University of Manchester, Manchester, United Kingdom.
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Tripodi A, Bressi C, Carpenedo M, Chantarangkul V, Clerici M, Mannucci PM. Quality assurance program for whole blood prothrombin time–international normalized ratio point-of-care monitors used for patient self-testing to control oral anticoagulation. Thromb Res 2004; 113:35-40. [PMID: 15081563 DOI: 10.1016/j.thromres.2004.01.009] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2003] [Revised: 01/15/2004] [Accepted: 01/16/2004] [Indexed: 10/26/2022]
Abstract
Whole blood coagulation monitors are increasingly used for patient self-testing to control oral anticoagulation, but there are no comprehensive quality assurance (QA) programs to check their performance. We report on the experience with one of such programs applied in a field study where patients on prothrombin time (PT)-international normalized ratio (INR) self-testing were asked to bring their monitors to the anticoagulation clinic for checking. PT-INR testing was performed three times over 3 months with 14 patient's monitors and test strips on three recalcified QA plasmas by an experienced laboratory operator. Each patient was also asked to perform PT-INR self-testing (his/her own capillary blood) which was then compared to the laboratory PT-INR (plasma). Overall, the comparison between the observed and the consensus PT-INR on QA plasmas was acceptable with the majority of measurements lying within +/-15% or 20% of the consensus values. The comparison between the PT-INR self-testing and the laboratory method was also acceptable: overall, there was no statistical significant difference between the mean PT-INR values and the majority of paired measurements were less than 15% or 20% apart. In conclusion, our results show that the proposed QA scheme is feasible and may be implemented on a larger scale. Monitors should be recalled periodically to the clinic where they have been prescribed to the patient. During each visit, the clinic may check the monitors and patient self-testing performance as described. Such comprehensive QA system would make monitoring of oral anticoagulant treatment by self-testing safer and more effective.
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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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Poller L, Keown M, Chauhan N, Van Den Besselaar AMHP, Tripodi A, Shiach C, Jespersen J. European Concerted Action on Anticoagulation. Correction of displayed international normalized ratio on two point-of-care test whole-blood prothrombin time monitors (CoaguChek Mini and TAS PT-NC) by independent international sensitivity index calibration. Br J Haematol 2003; 122:944-9. [PMID: 12956765 DOI: 10.1046/j.1365-2141.2003.04521.x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The international normalized ratio (INR) on two widely used point-of-care test (POCT) prothrombin time (PT) monitors (CoaguChek Mini and TAS PT-NC) differed considerably and also differed from the 'true' INR obtained on the same samples using a manual PT and the same species thromboplastin international reference preparation. Agreement between the displayed INR and difference from 'true' INR has been reassessed following an independent international sensitivity index (ISI) calibration of the two systems. The displayed INRs taken at seven centres were compared with 'true' INRs from the same blood donations and INRs based on the resulting ISI. The overall difference between the displayed INRs on the two monitor systems was reduced from 21.0% to 3.5%. The overall difference in mean INR of system A from the 'true' INR was reduced from 19.0% to 9.5% and of system B from 6.8% to 0.3%, but individual centre's results still showed considerable mean INR variability. Differences between overall displayed INR with the two monitor systems have been reduced by an independent multicentre calibration, and agreement with 'true' INR on the same blood samples improved. However, marked variability in mean INR at individual centres remained after ISI correction, which demonstrates the need for external quality control of individual POCT whole-blood PT monitors.
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Affiliation(s)
- Leon Poller
- ECAA Central Facility, School of Biological Sciences, The University of Manchester, Manchester, UK.
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Poller L, Keown M, Chauhan N, van den Besselaar AMHP, Tripodi A, Shiach C, Jespersen J. Reliability of international normalised ratios from two point of care test systems: comparison with conventional methods. BMJ 2003; 327:30. [PMID: 12842954 PMCID: PMC164241 DOI: 10.1136/bmj.327.7405.30] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 05/13/2003] [Indexed: 11/04/2022]
Abstract
OBJECTIVE To find out how accurately two point of care test systems--CoaguChek Mini and TAS PT-NC (RapidPointCoag)--display international normalised ratios (INRs). DESIGN Comparison of the INRs from the two systems with a "true" INR on a conventional manual test from the same sample of blood. SETTING 10 European Concerted Action on Anticoagulation centres. PARTICIPANTS 600 patients on long term dosage of warfarin. MAIN OUTCOME MEASURES Comparable results between the different methods. RESULTS The mean displayed INR differed by 21.3% between the two point of care test monitoring systems. The INR on one system was 15.2% higher, on average, than the true INR, but on the other system the INR was 7.1% lower. The percentage difference between the mean displayed INR and the true INR at individual centres varied considerably with both systems. CONCLUSIONS Improved international sensitivity index calibration of point of care test monitors by their manufacturers is needed, and better methods of quality control of individual instruments by their users are also needed.
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Affiliation(s)
- Leon Poller
- European Concerted Action on Anticoagulation Central Facility, School of Biological Sciences, University of Manchester, Manchester M13 9PT.
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Poller L, Keown M, Chauhan N, Van Den Besselaar AMHP, Tripodi A, Shiach C, Jespersen J. European Concerted Action on Anticoagulation (ECAA): an assessment of a method for ISI calibration of two whole blood point-of-care PT monitor systems based on lyophilized plasmas using whole blood equivalent PT. J Thromb Haemost 2003; 1:766-72. [PMID: 12871414 DOI: 10.1046/j.1538-7836.2003.00120.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Previously, the attempt to simplify the International Sensitivity Index (ISI) calibration of the CoaguChek Mini whole blood point-of-care test prothrombin time (PT) monitor system was successful using lyophilized plasmas from coumarin-treated patients but not with lyophilized artificially depleted plasmas. With the TAS PT-NC monitor system, both types of plasma failed to provide reliable calibrations. The present study assesses a procedure for the ISI calibration of a TAS PT-NC and CoaguChek Mini whole blood point-of-care test PT monitor systems using lyophilized plasmas. Using lyophilized artificially depleted and coumarin plasma calibrations, we have evaluated a correction for the monitor displayed PT. This was based on a 'line of equivalence' derived from the relationship between whole blood and fresh plasma PT with both types of monitor system. With the TAS PT-NC, the use of this 'line of equivalence' resulted in reliable ISI with both lyophilized coumarin and artificially depleted plasmas. There was no significant difference between mean monitor and mean reference International Normalized Ratio (INR) with the artificially depleted plasmas. With the lyophilized coumarin plasma calibrations there was only a small INR difference. Correction with the 'line of equivalence' therefore facilitates calibration of the TAS PT-NC with lyophilized plasmas. With the CoaguChek Mini, the correction based on the 'line of equivalence' did not improve results but was not required with this system.
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Affiliation(s)
- L Poller
- ECAA Central Facility, School of Biological Sciences, The University of Manchester, Manchester, UK
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Tripodi A, Chantarangkul V, Bressi C, Mannucci PM. International Sensitivity Index Calibration of the Near-Patient Testing Prothrombin Time Monitor, ProTime. Am J Clin Pathol 2003. [DOI: 10.1309/2p1abrk5bveeq78k] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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Poller L, Keown M, Chauhan N, van den Besselaar AM, Tripodi A, Jespersen J, Shiach C. European Concerted Action on Anticoagulation. Am J Clin Pathol 2003. [DOI: 10.1309/25bkyqep6858glfd] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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Poller L, Keown M, Chauhan N, van den Besselaar AMHP, Tripodi A, Shiach C, Jespersen J. European Concerted Action on Anticoagulation (ECAA). An assessment of lyophilised plasmas for ISI calibration of CoaguChek and TAS whole blood prothrombin time monitors. J Clin Pathol 2003; 56:114-9. [PMID: 12560389 PMCID: PMC1769887 DOI: 10.1136/jcp.56.2.114] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/28/2002] [Indexed: 11/04/2022]
Abstract
AIMS The recommended method for the international sensitivity index (ISI) calibration of whole blood point of care testing (POCT) prothrombin time (PT) systems was originally described by Tripodi et al in 1993 but is too complex and demanding. The present European Concerted Action on Anticoagulation (ECAA) study aimed to assess the reliability of simpler ISI calibration using lyophilised plasma samples. METHODS ISI calibrations using three different types of ECAA lyophilised plasma samples (artificially depleted, individual, and pooled coumarin) were compared with whole blood calibrations on CoaguChek Mini and TAS PT-NC POCT monitors at 10 centres. RESULTS With CoaguChek Mini systems, lyophilised coumarin plasma samples (both single donation and pooled) gave ISI and international normalised ratio (INR) values comparable to whole blood. With artificially depleted plasma, ISI and INR values were too high. With TAS PT-NC systems, all three types of lyophilised plasma samples gave inaccurate ISI and unreliable INR results, similar to previous ECAA findings with fresh plasma calibrations. CONCLUSIONS With CoaguChek Mini systems, ISI calibration can be simplified by the use of ECAA lyophilised plasma samples from coumarin treated patients. Further study is needed to devise a simpler calibration method for the TAS PT-NC system.
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Affiliation(s)
- L Poller
- ECAA Central Facility, School of Biological Sciences, The University of Manchester, Manchester M13 9PT, UK.
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Poller L, Keown M, Chauhan N, van den Besselaar AMHP, Tripodi A, Shiach C, Jespersen J. 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. Clin Chem 2002. [DOI: 10.1093/clinchem/48.10.1672] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
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.
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Affiliation(s)
- Leon Poller
- ECAA Central Facility, School of Biological Sciences, The University of Manchester, Manchester M13 9PT, United Kingdom
| | - Michelle Keown
- ECAA Central Facility, School of Biological Sciences, The University of Manchester, Manchester M13 9PT, United Kingdom
| | - Nikhil Chauhan
- ECAA Central Facility, School of Biological Sciences, The University of Manchester, Manchester M13 9PT, United Kingdom
| | - Anton MHP van den Besselaar
- Haemostasis and Thrombosis Research Centre, Leiden University Medical Center, 2333 ZA Leiden, The Netherlands
| | - Armando Tripodi
- A Bianchi Bonomi, Haemophilia and Thrombosis Centre, IRCCS Maggiore Hospital, University of Milan, 20122 Milan, Italy
| | - Caroline Shiach
- Department of Clinical Haematology, Manchester Royal Infirmary, Oxford Road, Manchester, M13 9WL Manchester, United Kingdom
| | - Jorgen Jespersen
- Department for Thrombosis Research, University of Southern Denmark and Department of Clinical Biochemistry, Ribe County Hospital, DK-6700 Esbjerg, Denmark
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Bhavnani M, Shiach CR. Patient self-management of oral anticoagulation. CLINICAL AND LABORATORY HAEMATOLOGY 2002; 24:253-7. [PMID: 12181030 DOI: 10.1046/j.1365-2257.2002.00443.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Patient self-management of oral anticoagulation is now widely practised in Germany and the USA. There are three different home-testing monitors available in the UK which are all reliable in terms of accuracy and reproducibility of results. Selected patients can be trained to perform their own International Normalized Ratio (INR) testing and dosing, with outcomes as good if not better than those from specialized anticoagulant clinics. Consensus on the frequency of testing and what quality control should be deployed is lacking. The cost-effectiveness in the UK is unproven.
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Affiliation(s)
- Manju Bhavnani
- Department of Haematology, The Royal Albert Edward Infirmary, Wigan Lane, Wigan WN1 2NN, UK.
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Poller L, Keown M, Chauhan N, van den Besselaar AMHP, Tripodi A, Shiach C, Jespersen J. European Concerted Action on Anticoagulation (ECAA). Minimum number of centres for reliable International Sensitivity Index calibration of CoaguChek and TAS point-of-care whole blood monitors. Thromb Res 2002; 107:61-6. [PMID: 12413591 DOI: 10.1016/s0049-3848(02)00179-2] [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: 11/22/2022]
Abstract
INTRODUCTION Prothrombin time (PT) test systems require multicentre calibration for reliable International Sensitivity Index (ISI). Multicentre calibration of CoaguChek Mini and TAS PT-NC point-of-care test (POCT) systems is less precise than conventional PT testing. The aim of the present study was to determine the number of centres required to give reliable ISI and International Normalised Ratio (INR) with these two POCT whole blood PT monitors. MATERIALS AND METHODS A simulation study, based on results of a 10-centre calibration exercise, was performed to assess reliability of ISI and INR when the number of centres was reduced from 10 to 2. RESULTS AND CONCLUSIONS With both systems, the range of ISI and INR deviation increased as the number of centres was reduced. For the CoaguChek Mini, at least five centres were needed for satisfactory INR deviation in 95% of calibrations. With the TAS PT-NC, three centres gave satisfactory INR at this level. The number of centres required for multicentre calibration of these two POCT PT systems is greater than the two proposed by World Health Organisation (WHO) Guidelines for conventional PT testing.
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Affiliation(s)
- L Poller
- ECAA Central Facility, School of Biological Sciences, The University of Manchester, 3 239 Stopford Building, M13 9PT, Manchester, UK.
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Poller L, Keown M, Chauhan N, van den Besselaar AMHP, Tripodi A, Jespersen J, Shiach C. Minimum numbers of fresh whole blood and plasma samples from patients and healthy subjects for ISI calibration of CoaguChek and RapidPointCoag monitors. Am J Clin Pathol 2002; 117:892-9. [PMID: 12047140 DOI: 10.1309/m1fe-ddvx-2v81-k5mp] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022] Open
Abstract
The international sensitivity index (ISI) calibration of point-of-care-test (POCT) prothrombin time (PT) whole blood monitors is complex, requiring manual PT testing of 60 patients' and 20 healthy subjects' plasma samples. The possibility of reducing these numbers was studied by a Monte Carlo Bootstrap study for 2 POCT PT systems. For reduced sample numbers, this consisted of 50,000 calibrations using whole blood and plasma samples tested on the monitors with manual PT testing of plasma samples from the same blood donations. There was little effect on mean ISI by reduction of sample numbers to a total of 7, but there was progressively less certainty regarding the reliability of the calibration. Precision of the calibrations and international normalized ratio deviation were not affected markedly by reducing numbers to half As ISI calibration with the 2 POCT systems was less precise than conventional manual testing, for maximum confidence, reduction of numbers is not advised.
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Affiliation(s)
- Leon Poller
- European Concerted Action on Anticoagulation, Central Facility, School of Biological Sciences, University of Manchester, England
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