Comment on the article by Toorop et al.: “The relationship between DOAC levels and clinical outcomes: The measures tell the tale”

Abstract

We read with great interest in your journal the paper by Toorop et al., 1 who argue that "it may be worthwhile to study the relationship between direct oral anticoagulant (DOAC) concentrations and patient-important outcomes." Although we agree that research on DOAC plasma level variability according to clinical factors and its association with relevant outcomes could be informative, we would like to put the proposal by Toorop et al. in a more appropriate clinical perspective.According to the article, this research topic would be of interest because "the overall major bleeding (MB) risk for DOAC use in observational studies remains 1% to 3% per year because of a large proportion of major extracranial bleeds." 1 This figure might look not so large compared to the rate of MB in the general population and in older subjects, which represents the majority of people receiving DOAC therapy, at least for stroke prevention in atrial fibrillation (AF). In a large study including 359,166 people without cardiovascular (CV) disease and not receiving antithrombotic therapies, the reported annual rate of MBs in subjects aged 70-79 years was 2.3% and 1.6% in men and women, respectively. 2 Therefore, when put in

The myths behind DOAC measurement: Analyses of prescribing information from different regulatory bodies and a call for harmonization

“…In DOACs, there is a chasm between intended use of the drugs with the advertised lack of requiring continuous or episodic monitoring and the reality of needing to measure DOAC levels in acute clinical settings. 14 , 15 , 16 , 17 , 18 , 19 Routine coagulation tests that have historically been useful and successful for assessing anticoagulation, such as the PT and APTT no longer serve as a warning beacon in the age of DOACs as their insensitivity or variable sensitivity to DOAC exposure limits their utility. 20 , 21 , 22 , 23 , 24 Other routine, albeit perhaps less commonly available, coagulation tests available for clinicians would be the thrombin time (TT) or anti‐FXa chromogenic assays.…”