Economic Outcomes in Patients at Risk for Venous Thromboembolism Receiving Appropriate Enoxaparin or Unfractionated Heparin Prophylaxis

Introduction: Venous thromboembolism (VTE) remains a frequent in-hospital complication in the United States (US) despite being largely preventable via the appropriate use of thromboprophylaxis. This study compared the economic outcomes of two frequently used thromboprophylaxis options (enoxaparin and unfractionated heparin [UFH]) in a large, real-world population of US medical and surgical patients at risk for VTE and receiving appropriate prophylaxis.

Methods: Discharges from the MarketScan® Hospital Drug Database from Thomson Reuters (Jan 04 – Mar 07) that were at risk of VTE (according to the 7^th American College of Chest Physicians [ACCP] guidelines), spent ≥6 days in hospital (to indicate a high VTE-risk population), and received appropriate (for dose and duration per the specific ACCP recommendation for the discharge’s primary medical diagnosis or surgical procedure) enoxaparin or UFH thromboprophylaxis, were included in the study. At least one day of enoxaparin ≥40 mg per day or UFH ≥10,000 units per day represented appropriate dose of prophylaxis. Prophylaxis duration was considered appropriate if it was received each day of the admission except two days for patients at medical risk (to allow for partial days of stay at admission and discharge), and each day of the admission after surgery except for two days in patients with surgical risk. Discharges that received other anticoagulants, inappropriate enoxaparin or UFH prophylaxis, or had contraindications to anticoagulation were excluded. Hospital costs were tallied for the duration of patient hospitalization and compared between enoxaparin and UFH groups (by intention to treat). Data are presented in US $ as mean ± standard deviation (SD). Multivariate analysis was performed to predict differences in hospital costs, using generalized linear models with patient and hospital characteristics as the explanatory variables. The costs of in-hospital clinical outcomes, such as VTE or bleeding, are reported within the overall costs.

Results: A total of 5,136 patients were included in the study, with 4,014 (78.2%) receiving appropriate enoxaparin prophylaxis and 1,122 (21.8%) receiving appropriate UFH prophylaxis. Total in-hospital length of stay was similar between patients receiving enoxaparin and UFH for both the qualifying admission (9.2±4.6 vs 9.6±5.2 days) and for total stay including readmissions (10.2 ± 5.9 vs 10.6 ± 6.5 days). The total mean hospital costs per discharge were $16,865 ± $10,979 in the enoxaparin group and $19,252 ± $14,970 in the UFH group. Room and board, operating room, and medical supply costs were lower with enoxaparin than with UFH, where as total pharmacy costs were higher with enoxaparin than with UFH (Table 1). In the univariate analysis, a mean saving of $2,388 was observed with enoxaparin (95% CI $1,596 to 3,180, p<0.001) and this translated to a non-significant adjusted mean difference of $439 (p=0.0716) in favor of enoxaparin following multivariate analysis.

Conclusions: These findings demonstrate that the appropriate use of enoxaparin prophylaxis for the prevention of VTE in at-risk hospitalized medical and surgical patients is associated with a non-significant reduction in total hospital costs compared with the appropriate use of UFH prophylaxis.

Table 1. Hospital costs for appropriate enoxaparin and UFH prophylaxis.