Related Experiment Videos
Laboratory reporting of the international normalized ratio: progress and problems
John D Olson1, John T Brandt, Wayne L Chandler
1Department of Pathology, University of Texas Health Science Center, San Antonio, TX 78229-3900, USA. olsonj@uthscsa.edu
Archives of Pathology & Laboratory Medicine
|November 6, 2007
Summary
Laboratory monitoring of oral anticoagulation using the international normalized ratio (INR) has improved significantly. Proficiency testing revealed fewer INR calculation errors, enhancing patient care quality.
Area of Science:
- Clinical Chemistry
- Hematology
- Laboratory Medicine
Background:
- The international normalized ratio (INR) is a critical parameter for monitoring oral anticoagulation therapy and assessing coagulation disorders.
- Variability in INR performance and reporting can impact patient safety and treatment efficacy.
Purpose of the Study:
- To assess the variability in the performance and reporting of the INR over a decade.
- To evaluate the accuracy of laboratory calculations for the INR.
Main Methods:
- A survey of laboratories participating in proficiency testing from 1993 to 2003.
- Collection of data on international sensitivity index (ISI) and mean normal prothrombin time (MNPT).
- Comparison of laboratory-reported INR with calculated INR to identify discrepancies.
Main Results:
- Significant improvements observed in INR reporting, reagent use (lower ISI), and method matching between 1993 and 2003.
- The all-method coefficient of variation for INR decreased from 18% to 5.8%.
- INR miscalculation rates dropped from 4.1% (2002-2003) to below 1% following the implementation of grading, with some errors corrected during the study.
Conclusions:
- Consensus recommendations for laboratory practice changes are implemented over extended periods.
- Documented difficulties in INR calculation have been addressed, leading to improved accuracy and reduced reporting variability.
- Effective proficiency testing programs, when actively evaluated and acted upon, demonstrably enhance the quality of patient care.