A Break-Even Cost Analysis for Venous Thromboembolism Prophylaxis in Posterior Lumbar Fusion Surgery

STUDY DESIGN: Break-even cost analysis. OBJECTIVES: This study uses a break-even cost-effectiveness model to assess whether enoxaparin is cost-effective for venous thromboembolism (VTE) prophylaxis in patients undergoing posterior lumbar fusion (PLF). METHODS: A 7-day course of enoxaparin 40 mg daily was evaluated using average retail drug costs and literature-based treatment costs for symptomatic VTE. VTE rates after PLF at 2, 3-6, and 7-12 vertebral segments were identified in the TriNetX Diamond database (2018-2023) for patients without prophylaxis. A break-even model calculated the absolute risk reduction and number needed to treat (NNT) for cost-effectiveness. RESULTS: The 7-day enoxaparin course cost $411.34, and treating a symptomatic VTE cost $20,461.32. The overall VTE rate was 0.49%; rates were 0.38% (2-segment), 0.65% (3-6 segments), and 2.7% (7-12 segments). Enoxaparin was cost-effective only for 7-12 segment fusions (NNT=50). Sensitivity analyses demonstrated cost-effectiveness for all PLF and 3-6 segment fusions if drug cost is ≤$100.00, or for 2-segment fusions if ≤$50.00. Alternatively, it is cost-effective if VTE treatment costs ≥$100,000 (all PLF, 2-segment) or ≥$75,000 (3-6 segments). CONCLUSIONS: Enoxaparin is cost-effective for PLF of 7-12 segments but not for PLF of fewer than 7 segments. Lower drug costs or higher treatment costs could make prophylaxis cost-effective for PLF of fewer segments.