Use of Lyophilized Calibration Plasmas and Control Blood for International Normalized Ratio Calculation in External Quality Assessment of the Prothrombin Time

1994 ◽  
Vol 102 (1) ◽  
pp. 123-127 ◽  
Author(s):  
Antonius M.H.P. ◽  
Van Den Besselaar
Keyword(s):  
Quality Assessment ◽  
Prothrombin Time ◽  
External Quality Assessment ◽  
International Normalized Ratio ◽  
External Quality ◽  
Ratio Calculation ◽  
And Control

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

1999 ◽  
Vol 82 (11) ◽  
pp. 1451-1455 ◽  
Author(s):  
L. L. Houbouyan-Reveillard ◽  
M. F. Aillaud ◽  
K. W. E. Denson ◽  
C. Droullé ◽  
M. Johnston ◽  
...  
Keyword(s):  
Prothrombin Time ◽  
External Quality Assessment ◽  
Calibration Procedure ◽  
International Normalized Ratio ◽  
Sensitivity Index ◽  
Local Calibration ◽  
External Quality ◽  
Different Types ◽  
Time Systems ◽  
International Sensitivity Index

SummaryThe 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.

scholarly journals Preparation of Control Blood for External Quality Assessment of Point-of-Care International Normalized Ratio Testing in the Netherlands

2014 ◽  
Vol 141 (6) ◽  
pp. 878-883 ◽  
Author(s):  
Anton M. H. P. van den Besselaar ◽  
Charmane F. Abdoel ◽  
Davina Ardanary ◽  
Gert van de Kamp ◽  
Fanny A. C. Versluijs
Keyword(s):  
The Netherlands ◽  
Quality Assessment ◽  
External Quality Assessment ◽  
Point Of Care ◽  
International Normalized Ratio ◽  
External Quality

scholarly journals External Quality Assessment of Point-of-Care Methods: Model For Combined Assessment of Method Bias and Single-Participant Performance by the Use of Native Patient Samples and Noncommutable Control Materials

2013 ◽  
Vol 59 (2) ◽  
pp. 363-371 ◽  
Author(s):  
Anne Stavelin ◽  
Per Hyltoft Petersen ◽  
Una Ø Sølvik ◽  
Sverre Sandberg
Keyword(s):  
Quality Assessment ◽  
External Quality Assessment ◽  
Point Of Care ◽  
International Normalized Ratio ◽  
Comparison Method ◽  
Case Scenario ◽  
External Quality ◽  
Target Values ◽  
Quality Specifications ◽  
Method Bias

BACKGROUND An important objective in external quality assessment (EQA) is to evaluate systematic deviations between methods. However, this is not possible when noncommutable control materials are used. The aim of this study was to develop an EQA model that incorporates a method bias evaluation using native patient samples into EQA schemes in which noncommutable materials are used. METHODS The model was applied twice in a point-of-care (POC) international normalized ratio survey among 1341 and 1578 participants. To estimate bias, about 100 native patient samples for each POC method were analyzed by a selected group of “expert” primary healthcare centers and on a designated comparison method. In addition, the expert centers as well as all the other EQA participants analyzed 2 noncommutable control materials, and method-specific target values were established. Both method bias and the deviation of a single-participant result from the method target value were evaluated against analytical quality specifications, making combined assessment possible. The best-case scenario occurred when both results were within the quality specifications. RESULTS Two POC methods fulfilled the quality specification for bias, whereas one did not. The best-case scenario was achieved by more than 90% of the participants using the methods with no bias, whereas none of the participants using the method with unacceptable bias achieved this result. CONCLUSIONS We propose an EQA model for which the bias of POC methods can be evaluated in situations in which commutable control materials are not available.

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