“…Although liquid chromatography-mass spectrometry (LC-MS) is still honored as a standard laboratory method for DOAC levels quantification [ 10 , 11 , 12 ], especially in the settings of preclinical/clinical research, there is a general consensus that the method is not very useful for the assessment of DOAC levels in routine clinical practice [ 13 ], mostly due to its limitations, such as bad availability, the need for specially equipped laboratory with specially skilled staff and time demands. Furthermore, standard coagulation test (prothrombin time, activated partial thromboplastin time, thrombin time) do not have sufficient sensitivity for DOAC levels assessment, especially when low DOAC levels are expected [ 10 , 13 ], and this could probably also be applied to standard reagents of novel viscoelastic hemostatic assays [ 14 ]. Therefore, DOAC-specific coagulation assays (ecarin clotting time assay or diluted thrombin time assays for dabigatran, and drug-specific chromogenic anti-Xa assays for apixaban, edoxaban and rivaroxaban) are arguably the most appropriate tests from the currently available laboratory methods for routine DOAC levels assessment ( Table 2 ), as the assays demonstrated good correlation with LC-MS [ 11 , 12 ] and good clinical utility in previous post-marketing studies [ 15 , 16 , 17 ].…”