PSHP 2026 Residency Conference

Purpose:  
The purpose of this study is to evaluate the impact of prophylactic anti-Xa monitoring on rates of venous thromboembolism (VTE) events and bleeding in trauma patients at a level one trauma center.  
 
 
Methods:  
This retrospective cohort study includes patients admitted to the trauma surgery service from January 2019 – July 2025 treated with enoxaparin for VTE prophylaxis. Exclusion criteria includes patients who spent 48 hours or more at a referring facility before transfer or an anti-Xa level collected before 3.5 hours of after 6.5 hours from last enoxaparin dose. Patients were identified via an Enterprise Information Management report, data was extracted from the electronic health record using REDCap, and statistical analysis was completed using Microsoft Excel. The primary outcome is rate of thromboembolic events, and secondary outcomes include rates of bleeding, units of red blood cells transfused, ICU and hospital length of stay (LOS). Categorical data is compared using a chi-squared test, and continuous data is reported using descriptive statistics. The study is IRB exempt by the institutional review board at the study site.  
 
Results:  
A total of 196 patients are included in the study; 91 received anti-Xa monitoring and 105 patients did not. No statistically significant differences in rates of VTE events were observed between patients who received anti-Xa monitoring compared with those who did not (9.9% vs 7.6%, p-value 0.573). Rates of bleeding were higher in the anti-Xa monitoring group (44.0% vs 26.7%, p-value 0.01). Patients who received anti-Xa monitoring were more likely to have missed doses of enoxaparin (56.0% vs 41.0% p-value 0.03) and had a longer median ICU LOS (13.6 days vs 6.3 days). In patients receiving anti-Xa monitoring, 48/91 (52.7%) patients had an initial anti-Xa within the goal range, and only 3/91 (2.2%) had an anti-Xa above the goal range.  
 
 
 
Conclusion: 
Anti-Xa monitoring did not result in a difference in VTE events and was associated with higher bleeding rates. However, the anti-xa monitoring group had more missed doses of enoxaparin and longer ICU length of stay, which are risk factors for VTE events. This suggests that patients who received anti-xa monitoring likely had a greater severity of illness, leading to higher rates or bleeding, despite not having supratherapeutic anti-xa levels.