Timing of venous thromboembolism chemoprophylaxis with major surgery of lower-extremity long bone fractures.

Background: There is debate on the need to withhold chemical venous thromboembolism (VTE) prophylaxis in patients requiring major orthopedic surgery. We hypothesized that the incidence of clinically significant hemorrhage (CSH) does not differ by the timing of prophylaxis in such patients.

Methods: This was a multicenter, retrospective cohort study conducted at five US trauma centers that included trauma patients admitted between January 1, 2018, to March 1, 2020, requiring surgical fixation of the femoral shaft, hip, or tibia and received VTE chemoprophylaxis during the hospitalization. Exclusions were major and moderate head or spinal injuries, chronic anticoagulant use, or multiple long bone surgeries. Timing of VTE chemoprophylaxis was examined as four groups: (1) initiated preoperatively without interruption for surgery; (2) initiated preoperatively but held perioperatively; (3) initiated within 12 hours postoperatively; and (4) initiated >12 hours postoperatively. The primary outcome was incidence of CSH (%), defined as overt hemorrhage within 24 hours postoperative that was actionable. Multivariate logistic regression evaluated differences in CSH based on timing of VTE chemoprophylaxis.

Results: There were 786 patients, and 65 (8.3%) developed a CSH within 24 hours postoperatively. Nineteen percent of patients received chemoprophylaxis preoperatively without interruption for surgery, 13% had preoperative initiation but dose(s) were held for surgery, 21% initiated within 12 hours postoperatively, and 47% initiated more than 12 hours postoperatively. The incidence and adjusted odds of CSH were similar across groups (11.3%, 9.1%, 7.1%, and 7.3% respectively; overall p = 0.60). The incidence of VTE was 0.9% and similar across groups ( p = 0.47); however, six of seven VTEs occurred when chemoprophylaxis was delayed or interrupted.

Conclusion: This study suggests that early and uninterrupted VTE chemoprophylaxis is safe and effective in patients undergoing major orthopedic surgery for long bone fractures.

Level Of Evidence: Therapeutic/Care Management; Level IV.