Analytical Performance of Eight New Coagulation Assays on the Cobas t 411 Analyser

Careful assessment of new laboratory methods for measurement of haemostatic function is required before routine use. We evaluated the analytical performance of eight new coagulation assays (Roche Diagnostics) on the cobas t 411 analyser, which has been developed for use in low-to-medium-throughput laboratories (100 tests/hour) and can be used to perform screening and specialised coagulation tests. Repeatability, intermediate precision and total reproducibility were assessed for the following assays on the cobas t 411 analyser: antithrombin, aPTT HighS, aPTT MedS, aPTT LowS, D-Dimer Gen 2, fibrinogen, PT Screen, and thrombin time. Experiments were conducted under routine conditions at three sites (UK, Germany, and the Netherlands) following ethical approval, using anonymised residual plasma samples or commercially purchased samples. Repeatability was determined using two or three control samples and five human plasma pool (HPP) samples covering the relevant measurement range (single run; 21 replicates). Intermediate precision and total reproducibility were evaluated over five days using two or three control samples and three HPP samples (one aliquot of each sample per day). Coefficients of variation (CV) were calculated. For control and HPP samples, the range of CVs across all sites for each parameter (repeatability; intermediate precision; total reproducibility, respectively) were: antithrombin (1.5-6.1%; 23-9.7%; 3.6-8.1%); aPTT HighS (0.4-3.1%; 1.1-4.8%; 4.2-13.1%); aPTT MedS (0.4-2.2%; 0.5-2.9%; 0.7-3.4%); aPTT LowS (0.5-4.0%; 0.5-4.9%; 2.9-5.3%); D-Dimer Gen 2 (0.8-2.9%; 0.7-4.0%; 1.5-5.8%); fibrinogen (0.8-13.3%; 1.7-10.7%; 4.2-9.3%); PT Screen (0.4-3.9%; 0.7-2.8%; 2.0-4.9%); thrombin time (1.2-14.6%; 2.6-3.3%; 3.4-4.1%). All coagulation assays demonstrated a robust analytical performance on the cobas t 433 analyser under routine conditions.