Predictors of complications of venous thromboembolism

Date of ISAC Approval: 
Lay Summary: 
Background Deep vein thrombosis is the formation of blood clot in deep veins, usually in a lower limb. Blood clots can break off and travel in the blood, may get trapped in the lung and result in a life-threatening pulmonary embolism. Together deep vein thrombosis and pulmonary embolism are known as venous thromboembolism (VTE). Treatment guidelines recommend use of blood thinners (anticoagulants) like heparin and warfarin to treat VTE and to prevent recurrent VTEs. The fear of severe bleeding from anticoagulants could result in physicians avoiding anticoagulants in patients who are likely to benefit from them. Bleeding in patients initially treated with anticoagulants could result in discontinuation of anticoagulant therapy and consequently in decreasing the benefit of anticoagulant therapy. Purpose of the study The relationship between recurrent VTE, bleeding and discontinuation of anticoagulant treatment in VTE patients is not well described. This study will investigate the frequency and predictors of VTE complications. Potential importance of the findings This study may help guide clinicians to identify patients for whom the benefits of anticoagulants outweigh the risks.
Technical Summary: 
Objectives This study will investigate the predictors for recurrent VTE, bleeding and discontinuation of Vitamin K antagonists (VKA). Methods Observational cohort study of patients with a first VTE between January 2008 and March 2015 who are given VKA within 60 days of the initial VTE. The study cohort will be identified through the CPRD and HES. Data analysis Multivariate hazard ratios will be derived from Cox regression models comparing patients with the presence of a covariate with those without the covariate. The models will include time-dependent predictors, such as new provoking events or new comorbid conditions. The cohort of patients with a first VTE initially treated with VKAs will form the basis for all analyses.
Health Outcomes to be Measured: 
Recurrent venous thromboembolism Bleeding events (defined as major bleeding and clinically relevant non-major bleeding events) Vitamin K antagonists discontinuation

Carlos Martinez - Chief Investigator - Institute for Epidemiology, Statistics and Informatics GmbH (Pharma Epi)
Alexander (Ander) Cohen - Collaborator - Kings College London
Anja Katholing - Collaborator - Institute for Epidemiology, Statistics and Informatics GmbH (Pharma Epi)

HES Admitted;HES Outpatient;ONS;Patient IMD;Practice IMD (Standard)