Background: There is little evidence to guide the perioperative management of patients on a direct oral anticoagulant (DOAC) in the absence of a last known dose. Quantitative serum titers may be ordered, but there is little evidence supporting this.
Aims: This multi-center retrospective cohort study of consecutive surgical in-patients with a DOAC assay, performed over a five-year period, aimed to characterize preoperative DOAC assay orders and their impact on perioperative outcomes.
Materials and methods: Patients prescribed regular DOAC (both prophylactic and therapeutic dosing) with a preoperative DOAC assay were included. The DOAC assay titer was evaluated against endpoints. Further, patients with an assay were compared against anticoagulated patients who did not receive a preoperative DOAC assay. The primary endpoint was major bleeding. Secondary endpoints included perioperative hemoglobin change, blood transfusions, idarucizumab or prothrombin complex concentrate administration, postoperative thrombosis, in-hospital mortality and reoperation. Adjusted and unadjusted linear regression models were used for continuous data. Binary logistic models were performed for dichotomous outcomes.
Results: 1065 patients were included, 232 had preoperative assays. Assays were ordered most commonly by Spinal (11.9%), Orthopedics (15.4%), and Neurosurgery (19.4%). For every 10 ng/ml increase in titer, the hemoglobin decreases by 0.5066 g/L and the odds of a preoperative reversal increases by 13%. Compared to those without an assay, patients with preoperative DOAC assays had odds 1.44× higher for major bleeding, 2.98× higher for in-hospital mortality and 16.3× higher for receiving anticoagulant reversal.
Conclusion: A preoperative DOAC assay order was associated with worse outcomes despite increased reversal administration. However, the DOAC assay titer can reflect the patient's likelihood of bleeding.
Keywords: Direct oral anticoagulation; Drug monitoring; patient safety/outcomes; perioperative medicine; pharmacology.