Multicenter Evaluation of Lyophilized and Deep-frozen Plasmas for Assignment of the International Normalized Ratio

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

doi:10.1055/s-0037-1614854

Thrombosis and Haemostasis, Table of Contents

Thromb Haemost 1999; 82(05): 1451-1455
DOI: 10.1055/s-0037-1614854

Rapid Communications

Schattauer GmbH

Multicenter Evaluation of Lyophilized and Deep-frozen Plasmas for Assignment of the International Normalized Ratio

A. M. H. P. van den Besselaar

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

,

L. L. Houbouyan-Reveillard

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, United Kingdom

,

C. Droullé

⁵Hôpital Robert Debré, Laboratoire Central d’hématologie, Reims, France

,

M. Johnston

⁶Hamilton Civic Hospitals Research Centre, Hamilton, Ontario, Canada

,

S. Kitchen

⁷Royal Hallamshire Hospital, Department of Haematology, Sheffield, United Kingdom

,

T. L. Lindahl

⁸University Hospital, Department of Clinical Chemistry, Linköping, Sweden

,

M. Marren

⁹Beaumont Hospital, Coagulation Laboratory, Department of Haematology, Dublin, Ireland

,

M. E. Martinuzzo

¹⁰University Institute of Biomedical Sciences, Favaloro Foundation, Buenos Aires, Argentina

,

A. Tripodi

¹¹A. Bianchi Bonomi Hemophilia and Thrombosis Center, Institute of Internal Medicine, University and IRCCS Maggiore Hospital, Milano, Italy

,

C. Vergnes

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

› Author Affiliations

Abstract

Summary

The interlaboratory variation of the International Normalized Ratio (INR) in various external quality assessment schemes is still relatively high. This is partly caused by inaccuracy of manufacturers’ stated International Sensitivity Index (ISI) and/or local instrumentation effects. The interlaboratory variation and accuracy of INR determinations may be improved by a local calibration procedure based on lyophilized plasmas with assigned INRs. The purpose of the present study was to determine INR values for different types of lyophilized plasmas to be used for local calibration. A total of 13 lyophilized plasmas (one normal, six from coumarin-treated patients, six artificially depleted) were analyzed by 10 laboratories, each using five calibrated prothrombin time (PT) systems. INRs were calculated for each plasma using each laboratory’s specific ISI and mean normal prothrombin time values. In the same way, five deep-frozen pooled plasmas from coumarin-treated patients were analyzed. There were significant INR differences for the lyophilized plasmas between the prothrombin time systems. The differences were relatively small for the deep-frozen coumarin plasmas (CV 2.6-3.3%) and three lyophilized coumarin plasmas from one manufacturer (CV 3.7-4.8%). Important INR differences were observed for three lyophilized coumarin plasmas from another manufacturer (CV 9.5-14.1%) and several artificially depleted plasmas (CV 5.3-12.8%). The citrate concentrations in the artificially depleted plasmas were lower than those in the normal and coumarin plasmas. These differences should be considered in the selection and certification of plasmas as calibrants for local calibration of PT systems. The lyophilized plasmas’ INR values obtained in the present study will be used for a field study of local PT calibration to assess their efficacy.

Keywords

Prothrombin time - International Normalized Ratio - thromboplastin - oral anticoagulant control - lyophilized plasma

Full Text

References

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