CC BY 4.0 · TH Open 2021; 05(04): e577-e584
DOI: 10.1055/s-0041-1740962
Original Article

Performance of the microINR Point-of-Care System Used by Self-Testing Patients: A Multicenter Clinical Trial

Majed A. Refaai
1   Department of Pathology and Laboratory Medicine, University of Rochester Medical Center, Rochester, New York, United States
Alan K. Jacobson
2   Department of Internal Medicine, VA Loma Linda Healthcare System, Loma Linda, California, United States
Jack C. Rosenfeld
3   Green and Seidner Family Practice Associates, Lansdale, Pennsylvania, United States
Robert R. Orr
4   Phoenix Medical Research, Peoria, Arizona, United States
› Author Affiliations


Introduction Anticoagulation monitoring is a major practical and clinical challenge. We assessed the performance of the microINR system in patient self-testing (PST).

Methods This study was performed at four US medical centers. After the training visit of warfarin anticoagulated patients (n = 117) on microINR system, PST was performed at home and in two visits to the medical centers. At the medical centers, both PST and healthcare professionals (HCPs) performed duplicate tests with the microINR System. A venous blood sample for the laboratory testing was also extracted. Accuracy and precision were assessed.

Results The comparison between microINR PST results and microINR HCP results revealed an equivalence with a slope of 1.00 (95% confidence interval [CI]: 1.00–1.00), and an intercept of 0.00 (95% CI: 0.00–0.00). When compared with the laboratory analyzer, microINR PST results also showed good correlation with a slope of 0.94 (95% CI: 0.86–1.04) and an intercept of 0.14 (95% CI: -0.09–0.34). Predicted bias values at international normalized ratio (INR) 2.0, 3.5, and 4.5 were 0% against HCP and ≤2.5% against the laboratory. Analytical agreement with both HCP and laboratory was 100% according to ISO17593 and 99.1 and 100% according to CLSI POCT14 with HCP and laboratory, respectively. Clinical agreement with HCP regarding 2.0–4.0 as INR therapeutic range was 98% (within range). The precision (coefficient of variation) of microINR system used by PST was comparable to HCP.

Conclusion The microINR results when used by self-testing patients show satisfactory concordance to both HCP results and laboratory analyzer. The microINR system is adequate for self-testing use.

Publication History

Received: 21 June 2021

Accepted: 04 November 2021

Article published online:
30 December 2021

© 2021. The Author(s). This is an open access article published by Thieme under the terms of the Creative Commons Attribution License, permitting unrestricted use, distribution, and reproduction so long as the original work is properly cited. (

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  • References

  • 1 Heneghan C, Alonso-Coello P, Garcia-Alamino JM, Perera R, Meats E, Glasziou P. Self-monitoring of oral anticoagulation: a systematic review and meta-analysis. Lancet 2006; 367 (9508): 404-411
  • 2 Heneghan C, Ward A, Perera R. et al; Self-Monitoring Trialist Collaboration. Self-monitoring of oral anticoagulation: systematic review and meta-analysis of individual patient data. Lancet 2012; 379 (9813): 322-334
  • 3 Ansell J, Jacobson A, Levy J, Völler H, Hasenkam JM. International Self-Monitoring Association for Oral Anticoagulation. Guidelines for implementation of patient self-testing and patient self-management of oral anticoagulation. International consensus guidelines prepared by International Self-Monitoring Association for Oral Anticoagulation. Int J Cardiol 2005; 99 (01) 37-45
  • 4 Ruff CT, Ansell JE, Becker RC. et al. North American Thrombosis Forum, AF Action Initiative Consensus Document. Am J Med 2016; 129 (5, Suppl): S1-S29
  • 5 Brown A, Wells P, Jaffey J. et al. Point-of-Care Monitoring Devices for Long-Term Oral Anticoagulation Therapy: Clinical and Cost Effectiveness [Technology Report No 72]. Canadian Agency for Drugs and Technologies in Health; 2007
  • 6 Grove EL, Skjøth F, Nielsen PB, Christensen TD, Larsen TB. Effectiveness and safety of self-managed oral anticoagulant therapy compared with direct oral anticoagulants in patients with atrial fibrillation. Sci Rep 2018; 8 (01) 15805 DOI: 10.1038/s41598-018-33531-7.
  • 7 Rose AJ, Berlowitz DR, Ash AS, Ozonoff A, Hylek EM, Goldhaber-Fiebert JD. The business case for quality improvement: oral anticoagulation for atrial fibrillation. Circ Cardiovasc Qual Outcomes 2011; 4 (04) 416-424
  • 8 Ng SS, Nathisuwan S, Phrommintikul A, Chaiyakunapruk N. Cost-effectiveness of warfarin care bundles and novel oral anticoagulants for stroke prevention in patients with atrial fibrillation in Thailand. Thromb Res 2020; 185: 63-71
  • 9 Phibbs CS, Love SR, Jacobson AK. et al; writing for the THINRS Executive Committee and Site Investigators. At-home versus in-clinic INR monitoring: a cost-utility analysis from the home INR study (THINRS). J Gen Intern Med 2016; 31 (09) 1061-1067
  • 10 Bernstein MR, John L, Sciortino S, Arambages E, Auletta D, Spyropoulos AC. Does telehealth improve anticoagulation management in patient service centers (PSC)? A pilot project. J Thromb Thrombolysis 2020; 49 (02) 316-320
  • 11 Nagler M, Raddatz-Müller P, Schmid P, Bachmann LM, Wuillemin WA. Accuracy of the point-of-care coagulometer CoaguChek XS in the hands of patients. J Thromb Haemost 2013; 11 (01) 197-199
  • 12 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 (02) 251-260
  • 13 Refaai MA, Shah V, Fernando R. Performance of the microINR point-of-care system: a multicenter clinical trial. Thromb Haemost 2020; 120 (04) 687-691
  • 14 CLSI H21–A5 Collection, Transport, and Processing of Blood Specimens for Testing Plasma-Based Coagulation Assays and Molecular Hemostasis Assays; Approved Guideline—Fifth Edition. Clinical and Laboratory Standards Institute; 2008
  • 15 CLSI EP09–A3 Measurement Procedure Comparison and Bias Estimation Using Patient Samples; Approved Guideline—Third Edition. Clinical and Laboratory Standards Institute; 2014
  • 16 ISO 17593:2007 Clinical Laboratory Testing and in Vitro Medical Devices–Requirements for in Vitro Monitoring Systems for Self-Testing of Oral Anticoagulant Therapy. International Organization for Standardization; 2007
  • 17 Goehe R, Riddick K. FDA Regulatory Oversight of POC PT/INR In Vitro Diagnostic Devices. In: FDA CDRH Public Workshop. 2016
  • 18 CLSI POCT14-Ed2 Point-of-Care Coagulation Testing and Anticoagulation Monitoring—Second Edition. Clinical and Laboratory Standards Institute; 2020
  • 19 Braun S, Watzke H, Hasenkam JM. et al. Performance evaluation of the new CoaguChek XS system compared with the established CoaguChek system by patients experienced in INR-self management. Thromb Haemost 2007; 97 (02) 310-314
  • 20 Barcellona D, Mastino D, Marongiu F. Portable coagulometer for vitamin K-antagonist monitoring: the patients' point of view. Patient Prefer Adherence 2018; 12: 1521-1526
  • 21 Kow CS, Sunter W, Bain A, Zaidi STR, Hasan SS. Management of outpatient warfarin therapy amid COVID-19 pandemic: a practical guide. Am J Cardiovasc Drugs 2020; 20 (04) 301-309