Prophylactic Subcutaneous Heparin Is Not Associated With Increased Rates of Hematoma, Pulmonary Embolism, or Deep Vein Thrombosis Following Lumbar Fusion: A Multi-Institutional, Propensity Score-Matched Analysis of 3,106 Patients.

Abstract

Retrospective multicenter cohort study. To compare the safety and efficacy of venous thromboembolism prophylaxis (VTE) strategies between two high-volume spine centers with distinct protocols. Postoperative VTE, including deep vein thrombosis (DVT) and pulmonary embolism (PE), remains a concern following spine surgery. The potential for epidural hematoma and associated neurologic compromise has limited consensus regarding the use of chemoprophylaxis. High-quality comparative data on prophylactic strategies are lacking. Patients undergoing one-to three-level lumbar fusion between 2017 and 2022 were retrospectively identified at two academic spine centers (n=3106). Patients received either mechanical-only prophylaxis or subcutaneous heparin (5,000 units three times daily) plus mechanical prophylaxis according to institutional protocol. Propensity score matching (1:1, caliper width 0.1, no replacement) was performed across demographic, surgical, and comorbidity covariates. Standardized mean differences <0.1 were considered acceptable. After matching, categorical outcomes were compared using chi-square or Fisher's exact tests as appropriate, and continuous variables were compared using two-sample t-tests. Co-primary outcomes were symptomatic epidural hematoma, DVT, and PE. Secondary outcomes included postoperative transfusion and timing of hematoma evacuation. Of 3,106 patients, 1,442 received mechanical-only prophylaxis and 1,664 received combined prophylaxis. The overall incidences of symptomatic epidural hematoma, DVT, and PE were 0.9% (n=29), 0.6% (n=18), and 0.2% (n=5), respectively. After matching, 647 pairs remained. There were no significant differences between prophylaxis groups in epidural hematoma (1.2% vs. 1.5%, P=0.81), DVT (0.2% vs. 0.9%, P=0.12), or PE (0.2% vs. 0.3%, P=1.0). Among patients undergoing one- to three-level lumbar fusion, the addition of subcutaneous heparin to mechanical prophylaxis did not reduce VTE incidence or increase the risk of symptomatic epidural hematoma. Routine chemoprophylaxis may not confer additional benefit in this population. Prognostic Level III.