Risk management of direct oral anticoagulant administration: An approach from the clinical laboratory

Abstract

 We established a system to easily estimate renal function, and a system to record the time from medication intake to testing using prothrombin time (PT) and activated partial thromboplastin time (aPTT) data in order to estimate the anti-coagulation effects in patients administered direct oral anticoagulants (DOACs). DOACs are contraindicated in patients who have severely impaired renal function due to their high renal excretion rates. The creatinine clearance rate (CCr), calculated using the Cockcroft-Gault formula, was adopted as the formal estimate of renal function in patients administered DOACs. In comparison with the estimated glomerular filtration rate (eGFR), the CCr tends to be lower in elderly patients with small physiques, who comprise a sizeable proportion of the population in Japan. Therefore, the CCr should be used instead of the eGFR value. We introduced the CCr in our laboratory system in order to determine which patients are contraindicated due to renal impairment and to follow-up the renal function of the patients periodically. Although DOACs are available for administration with a fixed dose and require no monitoring of their anti-coagulation effects, assessment of the anti-coagulant effects is desirable in patients at high risk of bleeding. Furthermore, the laboratory data vary depending on the time from drug intake to examination due to the short half-life of DOACs. In our hospital, the medical technologists record the time of intake when they collect blood from the patients, and this information is subsequently listed in the laboratory data reports. Thus, the risk of DOAC administration is managed by estimating the PT or aPTT while considering the time to testing from medication intake.