Study Compares Effectiveness of Treatments for Blood Clots


In an analysis of the results of nearly 50 randomized trials that examined treatments of venous thromboembolisms (blood clot in a vein), there were no significant differences in clinical and safety outcomes associated with most treatment strategies when compared with the low-molecular-weight heparin-vitamin K antagonist combination, according to a study in the September 17 issue of JAMA.

Venous thromboembolism, manifested as deep vein thrombosis or pulmonary embolism (blood clot in a lung), is a common medical condition and is the third leading cause of cardiovascular death. Clinicians have many potential treatment options regarding management of this condition, although little guidance exists about which treatment is most effective yet safe, according to background information in the study.

Lana A. Castellucci, M.D., of the Ottawa Hospital Research Institute, University of Ottawa, Ontario, Canada, and colleagues conducted a network meta-analysis to summarize and compare the efficacy and safety outcomes for the treatment of venous thromboembolism associated with 8 anticoagulation options (unfractionated heparin [UFH], low-molecular-weight heparin [LMWH], or fondaparinux in combination with vitamin K antagonists); LMWH with dabigatran or edoxaban; rivaroxaban; apixaban; and LMWH alone). The researchers conducted a search of the medical literature and identified 45 randomized trials (44,989 patients) for inclusion in the analyses.

The UFH-vitamin K antagonist combination was associated with a higher percentage of patients experiencing recurrent venous thromboembolism during 3 months of treatment (1.84 percent) than patients taking the LMWH-vitamin K antagonist combination (1.30 percent). Rivaroxaban and apixaban were associated with the lowest bleeding risk compared with the LMWH-vitamin K antagonist combination, with a lower proportion of patients experiencing a major bleeding event during 3 months of anticoagulation: 0.49 percent for rivaroxaban, 0.28 percent for apixaban, and 0.89 percent for the LMWH-vitamin K antagonist combination.

All other treatment regimens were associated with bleeding risks that did not differ significantly from the LMWH-vitamin K antagonist combination.

“To our knowledge, this network meta-analysis is the largest review, including nearly 45,000 patients, assessing the clinical outcomes and safety associated with different anticoagulation strategies for the treatment of acute venous thromboembolism. We provide estimates on symptomatic recurrent venous thromboembolism and major bleeding outcomes (both patient-important outcomes), which are clinically relevant and are what clinical practice guideline recommendations are based on,” the authors write.

“All management options, with the exception of the UFH-vitamin K antagonist combination, were associated with similar clinical outcomes compared with a management strategy using the LMWH­ vitamin K antagonist combination. Treatment using the UFH-vitamin K antagonist combination was associated with a higher risk of recurrent venous thromboembolism during the follow-up period.”
(doi:10.1001/jama.2014.10538;