Measurement of plasma direct oral anticoagulants concentrations in real-world clinical and laboratory settings on a 24/7 basis: a 10-year experience

Routine direct oral anticoagulant (DOAC) measurements are not recommended; however, they may be useful in some clinical situations. We sought to evaluate the everyday practice in DOAC measurements on a 24/7 basis including the number of tests over 10 years, indications in out- and inpatients, and turnaround time (TAT) in our tertiary center. From 2013 to 2023, we evaluated all consecutive 758 DOAC measurements performed in 628 patients, aged 61.9 ± 17.6 years mostly with venous thromboembolism (n = 211, 33.5%) and atrial fibrillation (n = 207, 33%) using chromogenic methods. The median number of tests was 6 per month (interquartile range (IQR) 3–9). There were parabolic trend lines for rivaroxaban (n = 308, 40.6%) and dabigatran (n = 241, 32.1%) measurements with a peak in 2017, while apixaban (n = 209, 27.3%) measurements were stable over the study period. The most common indications for DOAC measurements were drug-drug interactions (n = 92, 24.2%) and questionable adherence (n = 60, 15.9%) for outpatients (n = 380, 50.1%), while the assessment of residual DOAC concentrations before invasive procedures (n = 98, 28%) and in embolic stroke of undetermined source (n = 74, 19.6%) were for inpatients (n = 378, 49.9%) including 91 (12%) urgent samples. The median TAT was 89 min (63–126 min) and was shorter by 30 min at the night shifts (n = 256, 33.8%). For emergencies in 2023, TAT reached 42 min (34–54 min). To our knowledge, this is the longest study on how often, in whom, and for which reason DOAC measurements were requested over the last 10 years if a 24/7 service is available. We showed that DOAC measurements are stably requested in inpatients and outpatients but obtaining the results within 30 min is hardly feasible.