Intrarater and interrater variability of point of care coagulation testing using the ROTEM delta

This study aimed to assess intrarater and interrater variability of coagulation point-of-care testing (POCT) using ROTEM delta operated by trained staff. Arterial blood samples were taken from 43 anesthetized piglets aged up to 6 weeks and weighing 4-6 kg. The following clotting measurements were recorded: clotting time, clot formation time (CFT), maximum clot firmness (MCF) and alpha angle using ROTEM delta assays ExTEM, InTEM, FibTEM and ApTEM. Intrarater variability was assessed when a single operator performed the same assay simultaneously in all four channels of the ROTEM device. Interrater variability was assessed by two different operators simultaneously performing the same assay. Variance components of the data were analyzed using linear mixed modeling. Three hundred and forty-three tests from 86 samples were loaded and analyzed. The intraclass correlation coefficient (ICC) was more than 0.7 for clotting measurements except for CFT and alpha in InTEM. For intrarater and interrater assessment, different relative variability for the ROTEM measurements were found with consistently higher variability for clotting time and CFT and lower variability of MCF and alpha angle. Interrater variability was not statistically significant as supported using Akaike's information criterion. Piglet coagulation testing using ROTEM delta showed a high ICC. Variability was significantly lower in MCF and angle alpha compared with clotting time and CFT. No further variability was added by a second user. Based on these data, ROTEM delta appears to be suitable as POCT.