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Thromb Haemost 1987; 58(03): 905-910
DOI: 10.1055/s-0038-1646013
Original Article
Schattauer GmbH Stuttgart

Oral Anticoagulant Therapy Control: Evidence that INR Expression Improves the Inter-Laboratory Comparability of Results - The Bologna Oral Anticoagulant Control Exercise

G Palareti
1   The Dept. of Angiology and Blood Coagulation, Hosp. S. Orsola (head Prof. S. Coccheri, supervisor of the exercise), Italy
,
S Coccheri
1   The Dept. of Angiology and Blood Coagulation, Hosp. S. Orsola (head Prof. S. Coccheri, supervisor of the exercise), Italy
,
M Poggi
1   The Dept. of Angiology and Blood Coagulation, Hosp. S. Orsola (head Prof. S. Coccheri, supervisor of the exercise), Italy
,
M Bonetti
2   Central Laboratory, Hosp. S. Orsola (head Prof. G. Bugiardini), Italy
,
V Cervi
3   Institute for Cardiovascular Dis., Hosp. S. Orsola (head Prof. B. Magnani), Italy
,
A Mazzuca
4   Central Laboratory, Hosp. Malpighi (head Prof. F. Barboni), Italy
,
M Savoia
5   Central Laboratory, Hosp. Maggiore (head Prof. M. Martuzzi), Italy
,
L Veri
6   Central Laboratory, Hosp. Bellaria (head Prof. L. Abate), Italy
,
F Fiori
7   Central Laboratory, Orthopedic Institutes Rizzoli (head Prof. A. Pizzoferrato), Italy
,
G Gaspari
8   Laboratories of Clinical Chemistry Mengoli and Tiarini of the USL, (Local Health Unit) N. 28 (responsible Dr. G. Gaspari), Italy
,
A Palareti
9   Statistician, Institute of Computer Science, University of Ancona, Italy
,
The Bologna oral anticoagulant control study group › Author Affiliations
Further Information

Publication History

Received 05 December 1986

Accepted after revision 11 June 1987

Publication Date:
28 June 2018 (online)

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Summary

The aims of the present study were: l) interlaboratory normalization of prothrombin time (PT) testing for anticoagulant therapy control through calibration of customary thromboplastins against international reference materials, and 2) “on field” validation of the advantages offered by expression of results as International Normalized Ratio (INR) as opposedto percentage activity. PT tests were carried out over 8 days on the same normal subjects (16) and patients on oral an ticoagulants (48) in the 9 laboratories of the Bologna area. The use of customary thromboplastins and coagulometers was maintained in all labs throughout the study. The main results were: 1) the interlaboratory CV of the prothrombin ratios obtained for each sample with all customary thromboplastins (5 different brands) was 15%, but was reduced to levels of 5.8 to 8.9 when using constant thromboplastin brands and batches; 2) the International Sensitivity Index (ISI) values obtained in the different labs were only slightly influenced by the use of different coagulometers; 3) comparable ISI values were obtained through direct calibration with the international reference material and through intermediate calibration with a locally selected standard; 4) use of INR values instead of percentage activity greatly reduced interlaboratory variability and significantly improved uniformity of anticoagulation level measurements. thus reducing the possibility of erroneous prescriptions. The Bologna exercise is therefore of educational value for laboratory and community doctors of the area in understanding and accepting the INR system.

Keywords

Anticoagulant control - INR-PT normalization - PT expression
 

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