Meta-Analysis of Direct Oral Anticoagulants for the Treatment of Venous Thromboembolism in Patients with Active Malignancy
Authors: Mhaskar Rahul , Koipallil Gautamkrishna , Thomas Nelson , Visweshwar Nathan , Laber Damian A. , Patel Ankita K. , Jaglal Michael 
Published: October 2019

Abstract
Introduction
Venous thromboembolism (VTE), is the second leading cause of death in patients with cancer. The risk of VTE in patients with cancer is 4 to 7-fold, when compared to the general population. Even during anticoagulant treatment, the cumulative incidence of recurrent VTE is 3.5 times higher in patients with cancer than in cancer-free patients. Low-molecular-weight heparin has been the "gold standard" for the of treatment for VTE in cancer associated thrombosis, following the landmark trial by Lee et al.
Methods
We conducted a meta-analysis to evaluate the safety and efficacy of direct oral anticoagulants in patients with cancer. We systematically searched Medline for randomized-control clinical trials and post-hoc analyses. For each study, data on recurrent VTE, major or clinically relevant non-major bleeding (CRNMB), and major bleeding (MB) were extracted. We included randomized control trials (RCT's) where interventions consisted of direct oral anticoagulants (DOA) versus vitamin K antagonists (VKA) or low molecular weight heparins (LMWH), in which all or a part of the study population had active cancer. We excluded studies that were not comparing DOA versus VKA/LMWH or did not have a subset of active cancer patients.
Results
Seven studies met our eligibility criteria. Data for recurrent VTE was extractable from all 7 RCT's. There were 2178 enrolled participants total.
The pooled results show evidence for a lower incidence of recurrent VTE with the use of DOA versus VKA/LMWH. The pooled risk ratio for recurrent VTE was 0.68 (95% confidence interval 0.50 to 0.93; P = 0.01). There was negligible heterogeneity among the trials (I2 = 0%; P = 0.99).
Data for major bleeds was extractable from 6 RCT's, including 1952 enrolled participants total. The pooled results show no evidence for a difference in frequency of major bleeds with the use of DOA versus VKA/LMWH. The pooled risk ratio was 1 (95% CI 0.53 to 1.87; P= 0.99). There was moderate heterogeneity among trials (I2 = 40%; P = 0.17)
Data for clinically relevant bleeding was extractable from 6 RCT's, including 1952 enrolled participants total. The pooled results show no evidence for a difference in frequency of nonmajor but clinically relevant bleeds with the use of DOA versus VKA/LMWH. The pooled risk ratio was 1.06 (95% CI 0.80 to 1.42; P= 0.68). There was negligible heterogeneity among trials (I2 = 27%; P = 0.24).
Data for all bleeds (major or nonmajor) was extractable from all 7 RCT's. There were 2178 enrolled participants total. The pooled results show no evidence for a difference in frequency of bleeds with the use of DOA versus VKA/LMWH. The pooled risk ratio was 0.95 (95% CI 0.68 to 1.32; P= 0.74). There was substantial heterogeneity among trials (I2 = 65%; P = 0.02).
Conclusions
Our results suggest that DOACs might reduce the incidence of VTE recurrence in patients with cancer without putting them at high risk for major bleeds or clinically relevant nonmajor bleeds.
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Disclosures
No relevant conflicts of interest to declare.