Weight-based, anti-Xa guided enoxaparin after spine trauma surgery: target attainment and safety in a retrospective cohort.

BACKGROUND AND PURPOSE: Patients undergoing surgery for traumatic spine injuries have a high risk of venous thromboembolism (VTE). Standard fixed or weight-based enoxaparin regimens may leave some patients below prophylactic anti-factor Xa (anti-Xa) target ranges. Whether anti-Xa-guided enoxaparin dose adjustment can be implemented while maintaining acceptable observed bleeding outcomes has not been studied specifically in postoperative spine trauma patients. This study evaluates anti-Xa target attainment, symptomatic VTE, and safety outcomes after anti-Xa-guided enoxaparin titration.

METHODS

We performed a retrospective cohort study of adults (≥18 years old) who underwent operative treatment for traumatic spine injuries at a Level I trauma center. All patients received weight-based enoxaparin starting 24 h postoperatively (30 mg every 12 h if <90 kg, 40 mg every 12 h if ≥90 kg) plus mechanical VTE prophylaxis and early mobilization. In the anti-Xa cohort, levels were obtained 4 h after the third dose (target 0.2-0.4 IU/mL) and doses were adjusted by 10 mg if outside this range. A comparison cohort received the same initial dosing without anti-Xa monitoring. The primary outcome was symptomatic postoperative VTE. Secondary outcomes included bleeding requiring transfusion, spinal epidural hematoma, hospital length of stay, and ambulation at discharge.

RESULTS

A total of 354 patients were included (170 anti-Xa; 184 fixed dose). Symptomatic VTE was rare and similar between groups (1.1% vs. 1.6%). No postoperative epidural hematomas occurred. In the anti-Xa cohort, 28% required dose escalation and 7% required more than one adjustment. In exploratory adjusted analyses, bleeding requiring transfusion and length of stay did not differ between groups.

CONCLUSIONS

Weight-based enoxaparin with anti-Xa-guided titration was feasible after spine trauma surgery and identified a substantial subset of patients below the prespecified prophylactic anti-Xa target range. Protocol-based dose escalation was not associated with an observed increase in bleeding requiring transfusion, and no postoperative epidural hematomas occurred. Larger prospective studies are needed to determine whether improved anti-Xa target attainment translates into lower VTE rates.