Point of care monitoring of oral anticoagulant therapy in children: comparison of CoaguChek Plus and Thrombotest methods with venous international normalised ratio

Vera Ignjatovic; Chris Barnes; Fiona Newall; Simone Hamilton; Janet Burgess; Paul Monagle

doi:10.1160/TH04-02-0085

Thrombosis and Haemostasis, Table of Contents

Thromb Haemost 2004; 92(04): 734-737
DOI: 10.1160/TH04-02-0085

Theme Issue Article

Schattauer GmbH

Point of care monitoring of oral anticoagulant therapy in children: comparison of CoaguChek Plus and Thrombotest methods with venous international normalised ratio

Vera Ignjatovic

¹Department of Haematology, Royal Children’s Hospital, Melbourne, Victoria, Australia

,

Chris Barnes

¹Department of Haematology, Royal Children’s Hospital, Melbourne, Victoria, Australia

,

Fiona Newall

¹Department of Haematology, Royal Children’s Hospital, Melbourne, Victoria, Australia

,

Simone Hamilton

²Core Laboratory, Royal Children’s Hospital, Melbourne, Victoria, Australia

,

Janet Burgess

³Pathology Collection Department, Royal Children’s Hospital, Melbourne, Victoria, Australia

,

Paul Monagle

¹Department of Haematology, Royal Children’s Hospital, Melbourne, Victoria, Australia

› Author Affiliations

Abstract

Summary

This paper reports the outcome of a research protocol aimed at optimising warfarin monitoring in a tertiary pediatric centre. The Thrombotest™ INR was the standard monitoring test employed to manage oral anticoagulant therapy in children at the Royal Children’s Hospital (RCH), Melbourne. This study compares the results of this standard method to the novel CoaguChek® INR monitor and the “gold standard” technique of venous INR sampling. The objectives were to determine 1) if point-of-care techniques of measuring the INR (Thrombotest and CoaguChek) are accurate and reliable compared to INR results obtained from venous sampling, processed in an accredited laboratory, and 2) if INR results generated by POC devices can be safely used to manage oral anticoagulant therapy in children. 18 children (10 females and 8 males) participated in the study. Ages ranged from 9 months to 21 years (Mean 11.9 years; SD 5.03 years). The agreement between CoaguChek and venous INR measurements (r = 0.885) was shown to be higher compared to Thrombotest and venous INR (r = 0.700). Compared to the venous INR, values obtained with Coaguchek and Thrombotest crossed into or out of the therapeutic range in 25% and 36% of cases respectively. In 88% of the CoaguChek cases and 57% Thrombotest cases, the difference from the venous result was less than 0.5. The CoaguChek method of INR monitoring is a more accurate and reliable method compared to Thrombotest, in the pediatric population tested, and can be safely used to manage oral anticoagulant therapy in children.

Keywords

Anticoagulant monitoring - children - International Normalised Ratio (INR) - Point of Care (POC) - warfarin

Full Text

References

References
1 Andrew M, Monagle PT, Brooker L. Thromboembolic Complications during Infancy and Childhood. B.C. Decker Inc; 2000
2 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 (09) 3007-14.
3 Fyfe D, Kline C, Sade R. et al. Trans-oesphogeal echocardiography detects thrombus formation not identified by transthoracic echocardiography after the Fontan operation. J Am Coll Cardiol 1991; 17: 1152-60.
4 Michelson A, Bovill E, Monagle P. et al. Antithrombotic therapy in children. Chest 1998; 114: 748S-69S.
5 Belsey R, Fischer P, Baer D. An evaluation of a whole blood prothrombin analyzer designed for use by individuals without formal laboratory training. J Family Pract 1991; 33: 266.
6 Tripodi A, Arbini AA, Chantarangkul V. et al. Are capillary whole blood coagulation monitors suitable for the control of oral anticoagulation treatment by the International Normalized Ratio. Thromb Haemost 1993; 70: 921.
7 Yamreudeewong W, Johnson JV, Cassidy TG. et al. Comparison of 2 methods for INR determination in a pharmacist-based oral anticoagulation clinic. Pharmacotherapy 1998; 16: 1159.
8 White RH, McCurdy S, von Marensdorgg H. et al. Home prothrombin time monitoring after the initiation of warfarin therapy. Ann Intern Med 1989; 111: 7-30.
9 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 (04) 347-52.
10 Lin LI-K. A concordance correlation coefficient to evaluate reproducibility. Biometrics 1989; 45: 255-68.
11 Bland JM, Altman DG. Statistical methods for assessing agreement between two methods of clinical measurement. Lancet 1986; 307-10.
12 Kost GJ, Ehrmeyer S, Chernow B. The laboratory-clinical interface: Point-Of-Care testing. Chest 1999; 115: 1140-54.
13 Finck KM, Doekott C, Miller DR. Clinical impact of interlaboratory variation in International Normalized Ratio determinations. Am J Health Syst Pharm 2001; 58: 684-8.
14 Chapman DC, Stephens MA, Hamann GL. et al. Accuracy, clinical correlation, and patient acceptance of two handheld prothrombin time monitoring devices in the ambulatory setting. Ann Pharmacother 1999; 33 7–8 775-80.
15 Cosmi B, Palareti G, Carpanedo M. et al. Assessment of patient capability to self-adjust oral anticoagulant dose: a multicenter study on home use of portable prothrombin time monitor. (CoaguCheck) Haematologica 2000; 85: 826-31.
16 Van den Besselaar AM, Meeuwisse-Braun J, Schaefer-van Mansfeld H. et al. A comparison between capillary and venous blood international normalized ratio determinations in a portable prothrombin time device. Blood Coagul Fibrinolysis 2000; 11 (06) 559-62.
17 Murray ET, Fitzmaurice DA, Allan TF. A primary care evaluation of three near patient coagulometers. J Clin Pathol 1999; 52: 842-5.
18 Vacas M, Lafuente PJ, Cuesta S. et al. Comparative study of a portable monitor for prothrombin time determination, CoaguChek, with three systems for control of oral anticoagulant treatment. Haemostasis 1998; 28 (06) 321-8.
19 Douketis JD, Lane A, Milne J. et al. Accuracy of a portable International Normalization Ratio monitor in outpatients receiving long-term oral anticoagulant therapy: comparison with a laboratory reference standard using clinically relevant criteria for agreement. Thromb Res 1998; 92 (01) 11-7.
20 Gosselin R, Owings JT, White RH. et al. A comparison of point-of-care instruments designed for monitoring oral anticoagulation with standard laboratory methods. Thromb Haemost 2000; 83: 698-703.
21 Kemme MJB, Faaij RA, Schoemaker RC. Disagreement between bedside laboratory activated partial thromboplastin time and international normalized ratio for various novel anticoagulants. Blood Coagul Fibrinolysis 2001; 12: 583-91.
22 Massicotte P, Marzinotto V, Vegh P. et al. Home monitoring of warfarin therapy in children with a whole blood prothrombin time monitor. J Pediatr 1995; 127: 389-94.
23 Hobbs FD, Fitzmaurice DA, Murray ET. et al. Is the international normalised ratio (INR) reliable? A trial of comparative measurements in hospital laboratory and primary care settings. J Clin Pathol 1999; 57: 494-7.