Safety of Prothrombin Complex Concentrate for Emergency Surgery According to the Oral Factor Xa Inhibitor Level.

Anti-Xa assays are seldom rapidly available, prompting clinicians to frequently administer four-factor-prothrombin complex concentrate (4F-PCC) empirically.Determine if the thrombotic risk increases when preoperative factor Xa inhibitor (XaI) levels are low or unmeasured.We analyzed retrospectively all patients who received 4F-PCC between September 2018 and July 2024 at five hospitals in the Hamilton region and screened for those with emergency surgery/invasive procedure as the main indication. The primary outcomes were symptomatic or asymptomatic, objectively verified arterial or venous thromboembolism within 7 days of 4F-PCC infusion. The secondary outcome was the same between postoperative days 8 and 30. XaI levels were determined with an anti-Xa assay, calibrated with the respective oral anticoagulant used by the patient.Four-F-PCC at a median dose of 2,000 units (interquartile range, 2,000-2,000) was administered to 227 patients on apixaban (143; 63%), rivaroxaban (72; 32%), or edoxaban (12;5%). The mean age was 76 years, and 42% were female. Prophylaxis against venous thromboembolism was started promptly in 214 patients (94%) after a median of 1 day (interquartile range, 1-2). Thromboembolism within 7 days occurred in 1 of 38 patients (3%) with high XaI level, 0 of 24 with low level, and 9 of 165 (5%) with no level.The risk of thromboembolism after 4F-PCC in patients on XaI and emergency surgery/invasive procedures appears to be similar among patients with preoperative XaI levels that are high, low, or not measured. This information might be helpful in settings where rapid anti-Xa testing is unavailable.