Utility of anti-factor Xa monitoring in surgical patients receiving prophylactic doses of enoxaparin for venous thromboembolism prophylaxis.
BACKGROUND
Between 2% and 10% of the highest risk surgery, patients have a "breakthrough" venous thromboembolism (VTE) event despite receipt of chemoprophylaxis. The goals of this review are to summarize how patient-level factors may predict enoxaparin metabolism and how alterations in enoxaparin dose magnitude and frequency affect both anti-factor Xa (aFXa) levels and downstream VTE events.


METHODS
Relevant articles were identified on PubMed. Fixed-dose prophylaxis provides inadequate enoxaparin prophylaxis for most surgical patients based on anti-factor Xa levels. Inadequate enoxaparin dosing has been correlated with both asymptomatic and symptomatic VTE events. Patient-level factors such as gross weight and extent of injury predict enoxaparin metabolism. Weight-based or weight-tiered dosing regimens-and real-time dose adjustment based on anti-factor Xa levels-allow an increased proportion of patients to have in-range anti-factor Xa levels.


CONCLUSIONS
Inadequate enoxaparin dosing may explain why some patients have VTE despite enoxaparin prophylaxis. Ongoing research in the utility of weight-based or anti-factor Xa level driven enoxaparin dosing and dose adjustment is reasonable.
Division of Plastic Surgery, Division of Health Services Research, University of Utah, Salt Lake City, UT, USA. Electronic address: Christopher.Pannucci@hsc.utah.edu.
Christopher J
CJ
Pannucci
Department of Pharmacy Services, University of Utah, Salt Lake City, UT, USA.
Ann Marie
AM
Prazak
Division of Plastic Surgery, University of Utah, Salt Lake City, UT, USA.
Melody
M
Scheefer
D000925:Anticoagulants / Q000627:therapeutic use*; D017984:Enoxaparin / Q000627:therapeutic use*; D065427:Factor Xa Inhibitors / Q000097:blood*; D006801:Humans; D016343:Monitoring, Intraoperative; D011183:Postoperative Complications / Q000097:blood / Q000517:prevention & control*; D054556:Venous Thromboembolism / Q000097:blood / Q000517:prevention & control*
D000925:Anticoagulants; D017984:Enoxaparin; D065427:Factor Xa Inhibitors
Anti-factor Xa; Deep venous thrombosis; Drug metabolism; Enoxaparin; Pulmonary embolus; Venous thromboembolism