Risk of over-anticoagulation during acute kidney injury in patients treated with vitamin K antagonists.

Background Vitamin K antagonists (VKA) are still in use for oral anticoagulation, not all indications allow their replacement by direct oral anticoagulants (DOAC). Although formal dose reduction is not required in patients with impaired kidney function, case reports indicate that acute kidney injury (AKI) might be associated with derailment of VKA therapy. Methods The study retrospectively collected patients from a tertiary nephrology care center who experienced AKI while being treated with VKA. In these individuals, the international normalized ratio (INR) as a measure of anticoagulant effect during renal failure was compared to a reference time point with stable kidney function. Results One hundred patients with AKI and ongoing VKA therapy met the inclusion criteria. The majority (76%) of patients had AKI on CKD. Volume depletion (n = 43), septic renal failure (n = 22), decompensated heart failure (n = 18), toxic renal damage (n = 11) were the most important causes of AKI. The average INR values at the time of AKI were higher than at the reference time point (3.17 [1.10-13.0] vs. 2.24 [1.07-5.17], p Conclusions The effect of AKI on anticoagulation by VKA has not been systematically described. This risk should be considered in patients at high risk for AKI.