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

Summary

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

Keywords

Children - CoaguChek XS^® - point of care - reference thromboplastin - venous INR - warfarin

• References

• 1 Greenway A, Massicotte MP, Monagle P. Neonatal thrombosis and its treatment. Blood Rev 2004; 18: 75-84.
• 2 Monagle P, Chalmers E, Chan A. et al. Antithrombotic therapy in neonates and children: American College of Chest Physicians Evidence-Based Clinical Practice Guidelines (8th Edition). Chest 2008; 133 (06) Suppl 887S-968S.
• 3 Leichsenring I, Plesch W, Unkrig V. et al. Multicentre ISI assignment and calibration of the INR measuring range of a new point-of-care system designed for home monitoring of oral anticoagulation therapy. Thromb Haemost 2007; 97: 856-861.
• 4 Bereznicki LR, Jackson SL, Peterson GM. et al. Accuracy and clinical utility of the CoaguChek XS portable international normalised ratio monitor in a pilot study of warfarin home-monitoring. J Clin Pathol 2007; 60: 311-314.
• 5 Bauman ME, Black KL, Massicotte MP. et al. Accuracy of the CoaguChek XS for point-of-care international normalized ratio (INR) measurement in children requiring warfarin. Thromb Haemost 2008; 99: 1097-1103.
• 6 Marzinotto V, Monagle P, Chan A. et al. Capillary whole blood monitoring of oral anticoagulants in children in outpatient clinics and the home setting. Pediatr Cardiol 2000; 21: 347-352.
• 7 Monagle P, Barnes C, Ignjatovic V. et al. Developmental haemostasis. Impact for clinical haemostasis laboratories. Thromb Haemost 2006; 95: 362-372.
• 8 Andrew M, Paes B, Milner R. et al. Development of the human coagulation system in the healthy premature infant. Blood 1988; 72: 1651-1657.
• 9 Andrew M, Paes B, Milner R. et al. Development of the human coagulation system in the full-term infant. Blood 1987; 70: 165-172.
• 10 Williams VK, Griffiths ABM. Acceptability of CoaguChek S and CoaguChek XS generated international normalised ratios against a laboratory standard in a paediatric setting. Pathology 2007; 39: 575-579.
• 11 Tripodi A, Poller L, van den Besselaar AM. et al. A proposed scheme for calibration of international reference preparations of thromboplastin for the prothrombin time. On behalf of the Subcommittee on Control of Anticoagulation. Thromb Haemost 1995; 74: 1368-1369.
• 12 Hirsh JDJ, Anderson DR, Poller L. et al. Oral anticoagulants: mechanism of action, clinical effectiveness, and optimal therapeutic range. Chest 2001; 119: 8S-21S.
• 13 Grau E, Tenias JM, Olaso MA. et al. Monitoring oral anticoagulant treatment from plasma stored for up to 48 hours and frozen plasma. Haematologica 1999; 84: 633-636.
• 14 Dacie JVLS, Bain BJ, Bates I. Investigation of haemostasis. In: Dacie and Lewis’s Practical Haematology. Ninth Edition ed. Churchill Livingstone; 2001
• 15 bWHO. WHO Guidelines for Thromboplastins and Plasma Used to Control Anticoagulant Therapy. WHO Technical Report Series 889 1999; Annex 3: 64-93.
• 16 Monagle P, deVeber G, Massicotte M. Chapter 14: Vitamin K Antagonists: Warfarin and Acenocoumarol Therapy. In: Andrew’s Pediatric Thromboembolism and Stroke. Third ed. Hamilton, Ontario: BC Decker; 2006
• 17 Lin LI. A concordance correlation coefficient to evaluate reproducibility. Biometrics 1989; 45: 255-268.
• 18 Bland JM, Altman DG. Statistical methods for assessing agreement between two methods of clinical measurement. Lancet 1986; 01: 307-310.
• 19 Tripodi A, Arbini AA, Chantarangkul V. et al. Are capillary whole blood coagulation monitors suitable for the control of oral anticoagulant treatment by the international normalized ratio?. Thromb Haemost 1993; 70: 921-924.
• 20 Ignjatovic V, Barnes C, Newall F. et al. Point of care monitoring of oral anticoagulant therapy in children: comparison of CoaguChek Plus and Thrombotest methods with venous international normalised ratio. Thromb Haemost 2004; 92: 734-737.
• 21 Plesch W, van den Besselaar AM. Validation of the international normalized ratio (INR) in a new point-ofcare system designed for home monitoring of oral anticoagulation therapy. Int J Lab Hematol 2009; 31: 20-25.
• 22 Ansell JHJ, Hylek E, Jacobson A. et al. Pharmacology and Management of the Vitamin K Antagonists. CHEST 2008; 133 American College of Chest Physicians Evidence-Based Clinical Practice Guidelines (8th Edition) 160S-198.
• 23 Tripodi A. International collaborative study for the calibration of a proposed reference preparation for Thromboplastin, human recombinant. WHO Expert committee on biological standards, Geneva. Thromb Haemost 1998; 79: 439-443.
• 24 Baker RI, Coughlin PB, Gallus AS. et al. Warfarin reversal: consensus guidelines, on behalf of the Australasian Society of Thrombosis and Haemostasis. Med J Aust 2004; 181: 492-497.
• 25 Baker P, Gleghorn A, Tripp T. et al. Reversal of asymptomatic over-anticoagulation by orally administered vitamin K. Br J Haematol 2006; 133: 331-336.
• 26 Streif W, Andrew M, Marzinotto V. et al. Analysis of warfarin therapy in pediatric patients: A prospective cohort study of 319 patients. Blood 1999; 94: 3007-3014.
• 27 Newall F, Savoia H, Campbell J. et al. Anticoagulation clinics for children achieve improved warfarin management. Thromb Res 2004; 114: 5-9.