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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