Assessment of the Validity of the INR System for Patients with Liver Impairment

M J Kovacs; A Wong; K MacKinnon; K Weir; M Keeney; E Boyle; M Cruickshank

doi:10.1055/s-0038-1642513

Thrombosis and Haemostasis, Table of Contents

Thromb Haemost 1994; 71(06): 727-730
DOI: 10.1055/s-0038-1642513

Review Article

Schattauer GmbH Stuttgart

Assessment of the Validity of the INR System for Patients with Liver Impairment

M J Kovacs

¹The Department of Hematology/Blood Bank, Victoria Hospital, University of Western Ontario, London, Ontario, Canada

³The Department of Medicine, University of Western Ontario, London, Ontario, Canada

,

A Wong

¹The Department of Hematology/Blood Bank, Victoria Hospital, University of Western Ontario, London, Ontario, Canada

³The Department of Medicine, University of Western Ontario, London, Ontario, Canada

,

K MacKinnon

¹The Department of Hematology/Blood Bank, Victoria Hospital, University of Western Ontario, London, Ontario, Canada

,

K Weir

¹The Department of Hematology/Blood Bank, Victoria Hospital, University of Western Ontario, London, Ontario, Canada

,

M Keeney

¹The Department of Hematology/Blood Bank, Victoria Hospital, University of Western Ontario, London, Ontario, Canada

,

E Boyle

⁴The Departments of Biostatistics and Epidemiology, University of Western Ontario, London, Ontario, Canada

,

M Cruickshank

²The Department of Hematology, University Hospital, London, Ontario, Canada

³The Department of Medicine, University of Western Ontario, London, Ontario, Canada

› Author Affiliations

Abstract

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Summary

The INR system was developed to standardize PT reporting in patients on oral anticoagulants. We prospectively collected blood samples from 29 patients with liver impairment (INR 1.5-3.5). Control patients were on warfarin (n = 31). PT’s were measured on an ACL-300 with three thromboplastin reagents. INR’s were calculated using instrument specific ISI’s. Other tests performed were FDP’s, fibrinogen, aPTT, factors II, V, VII and X. The INR’s for each patient in the study population using the three thromboplastin reagents were significantly different (p = 0.0001). Those for the control population were not (p = 0.0658). Fibrinogen, factors V, II and X were different at the 5% level of significance between the populations. FDP’s were detected in 17 study subjects. The INR system is not valid for comparison of patients with liver impairment because different reagents do not give the same INR for the same sample. It is, however, no less valid than the use of PT with different thromboplastin reagents. Further study is recommended.

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References

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