Concordance Between Active Partial Thromboplastin Time and Anti-Factor Xa Assays in Neurocritically Ill Patients Receiving Subcutaneous Heparin Prophylaxis.

In neurocritically ill patients receiving prophylactic SQ-UFH with aPTT prolongation, there was poor concordance between aPTT and anti-factor Xa. This suggests that aPTT prolongation may not be solely driven by heparin activity and further evaluation of mechanistic drivers for coagulopathy in this population is necessary.