PURPOSE: While randomized controlled trials (RCTs) comparing pharmacologic regimens for venous thromboembolism (VTE) prophylaxis following orthopaedic surgeries have demonstrated differences in efficacy, these studies are criticized because they focus on venographic endpoints. We sought to confirm the findings of RCTs and to determine if differences noted in RCTs translate into “real-world” clinical outcomes.
METHODS: We retrospectively analyzed inpatient data from over 500 hospitals in the US. Adult patients admitted for hip fracture surgery between January 2003 and March 2005 were included. The occurrence of VTE (during hospitalization through 2 months post-discharge) served as the primary endpoint, determined by the presence of an ICD-9 code for either deep vein thrombosis (451.11, 451.19, 451.2, 451.81, 451.9 453.8, 453.9, 459.1x) or pulmonary embolism (415.1, 415.11, 415.19). We compared subjects given unfractionated heparin (UFH), enoxaparin, dalteparin, or fondaparinux post-surgery and during the inpatient stay. Logistic regression was employed to assess differences in VTE rates between the compounds, controlling for multiple confounders including: age, gender, Charlson severity score, mechanical ventilation, length of stay, cancer, other hypercoaguable states, hospitalizations prior to index visit, type of hospital, location of hospital, hospital bed size, presence of pneumatic compression stockings, aspirin or warfarin use.
RESULTS: A total of 49,461 patients were included (fondaparinux=2,551; dalteparin=4,501; enoxaparin=36,237; UFH=6,171). The unadjusted rates of VTE were: fondaparinux=2.0%, dalteparin=3.1%, enoxaparin=3.0%, UFH=5.0%. After adjusting for baseline covariates, patients were 40%, 40% and 90% more likely to develop a VTE within 2 months of inpatient treatment with dalteparin (OR 1.38, 95% CI: 0.99-1.92), enoxaparin (OR 1.40, 95% CI: 1.05-1.86), or UFH (OR 1.89, 95% CI: 1.39-2.58), respectively, compared to fondaparinux.
CONCLUSION: In a real world inpatient setting, anticoagulant choices for VTE prophylaxis after hip fracture result in distinct outcomes for patients. Fondaparinux use post hip fracture surgery is associated with the lowest rate of VTE.
CLINICAL IMPLICATIONS: The findings of RCTs correlate with clinically meaningful differences in medical practice. Broader use of fondaparinux following hip fracture surgery may decrease VTE rates.
DISCLOSURE: Andrew Shorr, Grant monies (from industry related sources) GSK, Sanofi Aventis; Consultant fee, speaker bureau, advisory committee, etc. GSK, Sanofi Aventis.