INTRODUCTION: The aim of this study is to raise awareness in the laboratory staff and physicians that Prothrombin Time-International Normalized Ratio (PT-INR) tests are not reliable in the patients receiving in general DOACs treatment and, in particular dabigatran.
METHODS: PT-INR tests were performed in 151 plasma specimens by three coagulation analyzers with different methodologies: (i) The analyzer in use was Thrombolyzer XRM which uses optomechanical method, (ii) The newly installed analyzer Diagon CoagXL which uses optical method, (iii) The reference method Stago STA Compact which uses mechanical method. All results were analyzed by intraclass correlation coefficient (ICC), Passing and Bablok regression analysis and Bland Altman analysis methods were used to examine the consistency of measurement techniques. It was understood that new generation oral anticoagulant (dabigatran) was used in 23 patients and unacceptable results were observed for accuracy and precision.
RESULTS: The Stago STA Compact -Thrombolyser PT-INR Intraclass Correlation Coefficient (ICC) was higher than Stago STA Compact -Diagon CoagXL, and 95% confidence interval (CI) was narrow. The Passing & Bablok regression analysis including all results, there was a significant deviation from the linearity (p<0.01), but there was no significant deviation from the linearity when the results of the patients using dabigatran were excluded. According to the statistics of comparison studies, excluding patients using dabigatran, the results reached more acceptable limits.
DISCUSSION AND CONCLUSION: It was found that the use of new generation oral anticoagulant (dabigatran) as a source of preanalytical error in some patients when consulted with the clinics requesting the test. It will be of great benefit for clinicians to communicate with and inform laboratory specialists in the follow-up of patients other than traditional anticoagulation cases.