Venous Thromboembolism After Coronary Artery Bypass Increases Healthcare Costs: A Propensity Score Matched Analysis

A. M. Wisniewski¹, M. El Moheb¹, N. Polavarapu¹, A. Norman², S. Young³, M. P. Weber¹, S. W.W.. Noona¹, A. Sharma¹, N. Teman^1
1University of Virginia, Charlottesville, Virginia ²University of Virginia Health Systems, Charlottesville, Virginia ³UVA, Troy, Virginia

Purpose: Venous thromboembolism (VTE) after cardiac surgery is rare but may increase hospital resource utilization. Despite the adverse clinical implications, its economic impact is unknown. We sought to determine the cost associated with development of VTE in patients undergoing isolated coronary artery bypass grafting (CABG).

Methods: We identified Society of Thoracic Surgeons Adult Cardiac Database data for all patients undergoing isolated CABG from 2010-2020 within a regional collaborative. Those undergoing off-pump revascularization, major concomitant procedures, emergent operations, those requiring perioperative mechanical circulatory support or with missing cost data were excluded. VTE was defined as any deep vein thrombosis or pulmonary embolism occurring in-hospital or within 30 days of index operation. Patients were propensity score matched via optimal full matching with threshold standard mean difference (SMD) between -0.1 and 0.1. Cost analysis was performed on matched groups utilizing a weighted linear regression model and a marginal effects analysis was used to determine respective total hospital costs.

Results: A total of 18,165 patients were analyzed including 232 that developed VTE (1.3%). Patients with VTE were significantly older (68 [59, 75] years vs. 65 [58, 72] years, p< 0.001), more likely to be female (31.5% vs. 24.4%, p=0.01), have longer time from admission to surgery (3 [1, 5] days vs. 2 [0, 4] days, p< 0.001), and higher median STS predicted risk of mortality (PROM, 1.2% [0.7%, 2.2%] vs. 0.9% [0.5%, 1.7%], p< 0.001). Following optimal full matching, the SMD was approximately 0 suggesting a balanced sample. Weighted linear regression demonstrated VTE as significantly increasing total cost of hospital stay by an average of $13,800 (p < 0.001). This cost was driven mostly by an increase in intensive care unit expenditure ($4,580) followed by pharmacy costs ($2,616) and then step-down unit costs ($1,786, all p< 0.001). The average cost for a patient after CABG with VTE was $47,761.84 compared to $33,965.15 for those without VTE on analysis of marginal effects. This increased per-patient cost equated to approximately $3.2 million more for all patients developing VTE after CABG during the study period.

Conclusion: Development of VTE following isolated CABG is associated with a significant increase in healthcare costs driven mostly by increased ICU, pharmacy, and step-down unit costs. Appropriate prophylactic measures are warranted to prevent development of this complication.

Identify the source of the funding for this research project: T32