A-167 Validation of the ROTEM Sigma System: Assessing Accuracy, Precision, and Reference Interval Verification against the ROTEM Delta

Abstract Background Rotational thromboelastometry (ROTEM) is a useful tool for rapid assessment of coagulation status using whole blood patient samples. ROTEM is increasingly implemented in point-of-care settings to guide bleeding management and transfusion practices. The newer ROTEM sigma is a fully automated cartridge-based system that offers streamlined test operation, whereas its predecessor ROTEM delta requires pipetting of blood samples by trained personnel. Here, we verify reference intervals for the ROTEM sigma recently introduced at our institution, evaluate its precision, and compare results to the ROTEM delta. Methods The results of three new ROTEM sigma devices were compared to one ROTEM delta device, the existing reference method at our institution. Blood samples were run on both systems using the EXTEM, INTEM, FIBTEM, and HEPTEM tests on the ROTEM delta and the corresponding “complete + hep” cartridge on the ROTEM sigma (which includes the four aforementioned parameters). Correlations between the new and old instruments were evaluated for the following standard parameters: clotting time (CT), amplitude at a specific time after CT (A[number of minutes]), maximum clot firmness (MCF), and maximum lysis (ML). Precision of results for CT, A5, A10, and A20 were evaluated by running a normal and an abnormal sample 21 times on all three ROTEM sigma devices. Verification of proposed reference intervals for each parameter was conducted with 20 blood samples run on one of the ROTEM sigma instruments. Analysis was performed by EP Evaluator. Results Of the standard parameters and tests performed across all three new ROTEM sigma devices, the vast majority of results demonstrated very strong (r > 0.9) or strong correlation (r = 0.7-0.89) with measurements from the ROTEM delta. Few results, such as CT and ML, showed moderate correlation (r = 0.4-0.69) (Table 1). Samples for precision showed a coefficient of variation < 5% across all three ROTEM sigma instruments for the tested parameters, except negative control samples for EXTEM-CT which had a coefficient of variation < 8%. Proposed reference intervals for key parameters included: EXTEM-CT (51-73 sec), EXTEM-A5 (33-52 mm), EXTEM-A10 (45-62 mm), EXTEM-A20 (54-69 mm), EXTEM-MCF (57-72 mm), EXTEM-ML (0-6 mm), EXTEM lysis index 60 minutes after CT (LI60) (94-100%); FIBTEM-A5 (5-16 mm), FIBTEM-A10 (6-17 mm), FIBTEM-A20 (6-18 mm), FIBTEM-MCF (6-19 mm); HEPTEM-CT (141-215 sec), HEPTEM-A5 (33-51 mm), HEPTEM-A10 (44-61 mm), HEPTEM-A20 (52-67 mm), HEPTEM-MCF (54-69 mm); INTEM-CT (139-205 sec), INTEM-A5 (36-54 mm), INTEM-A10 (46-63 mm), INTEM-A20 (53-68 mm), INTEM-MCF (55-70 mm), INTEM-ML (0-7 mm), INTEM-LI60 (93-100%). All proposed reference ranges passed verification testing, with <10% of results observed outside of the proposed intervals. Conclusion The ROTEM sigma demonstrated high reproducibility and precision of results for standard coagulation parameters. Measurements between the ROTEM sigma and ROTEM delta instruments also showed strong correlation, indicating that the ROTEM sigma values would result in similar clinical decisions being made. Following verification of reference ranges at our institution, we conclude the ROTEM sigma performs well enough to replace ROTEM delta without significantly modifying decision-making in the appropriate clinical settings.