Evaluation of measurement uncertainty of coagulation parameters according to two different current guidelines

Evaluation of measurement uncertainty of coagulation parameters according to two different current guidelinesS ince laboratory results are crucial in the diagnosis, treat- ment, follow-up, and risk assessment of diseases, accurate and reliable measurements are essential.Measurement uncertainty (MU) is a concept that characterizes the distribution of values that can be attributed to a measurement to evaluate the reliability and accuracy of the analysis result [1].MU is not a doubt about the validity of the measurement but rather a defined confidence limit.MU can also provide laboratory users with confirmation that patient results meet performance specifications [2].MU components must be identified throughout the entire traceability chain, starting with reference material providers, through in vitro diagnostic manufacturers, pro-cesses for assigning calibrator values, and finally, the result.In addition to uncertainties in the steps of the metrological chain, test results are also affected by uncertainties arising from random effects in laboratory measurements [3].Apart from uncertainties due to matrix effects, interferences, environmental factors, reference materials, and calibrators, differences in the methods and procedures used in calculating MU also contribute to MU.The ISO/TS 20914:2019 guideline recommends calculating MU after each of the three main MU sources has been estimated.According to this guideline, the MU value should primarily be calculated based on longterm uncertainty (uRW) and calibrator uncertainty (uCAL),Objectives: This study aims to calculate the measurement uncertainty values of prothrombin time (PT), activated partial thromboplastin time (APTT), D-dimer, and fibrinogen tests according to ISO/TS 20914 and Nordtest 2017 guidelines and to compare these values with the total allowable error (TEa%) and maximum expanded allowable measurement uncertainty (MAU) values established by international organizations.Methods: Normal and pathological level internal quality control data for PT, APTT, D-dimer, and fibrinogen tests performed on the Sysmex CS2100 device between January and May 2024 were obtained from the Laboratory Information System.External quality control data for October 2023 and September 2024 were sourced from the external quality control system.Measurement uncertainty was calculated following ISO/TS 20914 and Nordtest 2017 guidelines.Results: According to the ISO/TS 20914 guideline, the measurement uncertainty values for PT, APTT, D-dimer, and fibrinogen tests were 10.42%, 3.49%, 4.81%, and 19.10%, respectively.According to the Nordtest guideline, the measurement uncertainty values were 10.44%, 12.64%, 17.94%, and 21.69%, respectively.Conclusion: Based on the ISO/TS 20914 guideline, it was observed that the measurement uncertainty values for all coagulation tests met the TEa% analytical targets.According to the Nordtest guideline, all tests except fibrinogen met these targets.When evaluated against the MAU criterion, it was determined that D-dimer met the targeted quality specification according to both guidelines; however, the measurement uncertainty values for PT, APTT, and fibrinogen exceeded the allowed targets.Standardization of the measurement uncertainty calculation model and the determination of analytical targets based on laboratory priorities can ensure reliable monitoring of analytical performance.