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

INTRODUCTION: 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.
DISCUSSION AND 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.