Influence of Three Types of Automated Coagulometers on the International Sensitivity Index (ISI) of Rabbit, Human, and Recombinant Human Tissue Factor Preparations

A. M. H. P. van den Besselaar; L. L. Houbouyan; M. F. Aillaud; K. W. E. Denson; M. Johnston; S. Kitchen; T. L. Lindahl; M. Marren; M. E. Martinuzzo; C. Droullé; A. Tripodi; C. Vergnes

doi:10.1055/s-0037-1614420

Thrombosis and Haemostasis, Table of Contents

Thromb Haemost 1999; 81(01): 66-70
DOI: 10.1055/s-0037-1614420

Review Article

Schattauer GmbH

Influence of Three Types of Automated Coagulometers on the International Sensitivity Index (ISI) of Rabbit, Human, and Recombinant Human Tissue Factor Preparations

A Multicenter Study

Authors

A. M. H. P. van den Besselaar

¹From the Haemostasis and Thrombosis Research Center, Leiden University Medical Center, Leiden, The Netherlands
L. L. Houbouyan

²Hôpital Ambroise Paré, Service Central d'immuno-hématologie, Boulogne, France
M. F. Aillaud

³Hôpital de la Timone, Laboratoire d'hématologie, Marseille, France
K. W. E. Denson

⁴Thame Thrombosis and Haemostasis Research Foundation, Thame, Oxon, UK
M. Johnston

⁵Hamilton Civic Hospitals Research Centre, Hamilton, Ontario, Canada
S. Kitchen

⁶Royal Hallamshore Hospital, Department of Haematology, Sheffield, UK
T. L. Lindahl

⁷University Hospital, Department of Clinical Chemistry, Linköping, Sweden
M. Marren

⁸Beaumont Hospital, Coagulation Laboratory, Department of Haematology, Dublin, Ireland
M. E. Martinuzzo

⁹University Institute of Biomedical Sciences, Favaloro Foundation, Buenos Aires, Argentina
C. Droullé

¹⁰Hôpital Robert Debré, Laboratoire Central d'hématologie, Reims, France
A. Tripodi

¹¹A. Bianchi Bonomi Hemophilia and Thrombosis Centre, IRCCS Maggiore Hospital, Milano, Italy
C. Vergnes

¹²Hôpital Cardiologique Haut Lévêque, Laboratoire d'hémobiologie, Pessac, France

Abstract

Summary

Five tissue factor reagents and three types of automated instruments for prothrombin time (PT) determination were studied in an international multicenter collaborative exercise. The purpose of this work was to determine the international sensitivity index (ISI) for each combination of reagent and instrument against the international reference preparation RBT/90. Each type of instrument was used by 3 or 4 centers to assess the interlaboratory variation of the ISI. The interlaboratory variation of the ISI for each combination of reagent and instrument ranged between 0.4% and 7.8% coefficient of variation. For three reagents, the mean ISI values for ACL (nephelometric) and STA (mechanical) were practically identical, but the mean ISI values for MLA (photo-optical) were at least 10% higher. For two other reagents prepared from rabbit tissue, the mean ISI values increased in the order ACL, STA, MLA. The widest range of mean ISI values was noted with one rabbit tissue factor reagent: 1.68 for ACL and 2.00 for MLA. Exclusion of patient specimens with INR <1.5 and INR >4.5 determined by the international reference preparation resulted in a slight decrease of the mean ISI.

The interlaboratory variation of the International Normalized Ratio (INR) was assessed from the results obtained with common lyophilized and deep-frozen plasmas. The use of instrument-specific ISI values resulted in reduced interlaboratory variation of the INR. It is recommended that thromboplastin manufacturers provide instrument-specific ISI values.

Full Text

References

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