The University of California, San Francisco and Kaiser Permanente California have received more than $3.5 million to fund a study that will compare the effectiveness of both new and older blood-thinning medications in preventing dangerous blood clots in the veins and lungs.
Blood thinners, or anticoagulants, prevent the production of certain proteins that are needed for blood to clot. They are used in hospitals to treat blood clots in the lung, or pulmonary embolism. It's estimated that pulmonary embolisms cause up to half a million hospitalizations and 100,000 deaths every year in the United States.
Four newer anticoagulant drugs ¾ dabigatran, rivaroxaban, apixaban and edoxaban ¾ are now available to treat clots in addition to the blood thinner warfarin, which has been in use for more than 60 years. These anticoagulants are frequently used for longer than the standard three-month treatment period to prevent additional clots from forming, but the comparative safety and effectiveness of such extended use is not clear. Although effective treatments, these drugs also can cause serious bleeding, including in the brain.
"As the Medical Director of our local Anticoagulation Clinic, I see firsthand the challenges that patients and clinicians face every day when deciding which anticoagulant medication to take and how long to stay on treatment, given the limited amount of data to guide those decisions" noted UCSF lead investigator Margaret C. Fang, MD, MPH, Research Director, UCSF Division of Hospital Medicine.
The study was selected for funding by the Patient-Centered Outcomes Research Institute (PCORI) to address important evidence gaps and questions that people who have had blood clots and other healthcare stakeholders identified as their top priorities through PCORI's research prioritization process.
"There have been no studies comparing the newer oral blood-thinning drugs for extended treatment of blood clots in veins and lungs. This project has the potential to fill an important gap in our health knowledge and clinical approach," said Alan S. Go, MD, chief of Cardiovascular and Metabolic Conditions at the Kaiser Permanente Northern California Division of Research. "We look forward to working with PCORI to gain new insights and share our findings."
The research team will review thousands of records of members of Kaiser Permanente Northern California and Southern California who either took one of the five drugs for extended periods of time as a preventive measure or stopped taking the drugs once their clots were resolved. It also will compare outcomes associated with each of the drugs and look at whether the benefits and harms differ for patients who are older, have impaired kidney function, or a higher predicted risk of bleeding.
A key stakeholder in the study is the National Blood Clot Alliance (NBCA). "We're honored to be a patient-focused partner in this important research program," said NBCA Chief Executive Officer Randy Fenninger, JD. "The results of this study will fill important information gaps by demonstrating diverse patient experiences with various treatment options, and enable patients and clinicians alike to make informed, patient-centered treatment decisions."
The main outcome of the study is the net benefit of one treatment strategy compared with another, measured in terms of the number of venous thromboembolism events (VTE) prevented and the number of bleeding complications caused. Because the study is an observational study of actual clinical care, advanced statistical techniques will be applied to maximize the validity of the results.
"A unique aspect of our study is that not only will we be looking at clinical outcomes such as bleeding and recurrent clots, but we will also survey people to ask them about their experiences with anticoagulants in terms of quality of life and treatment satisfaction," noted Kristi Reynolds, PhD, MPH, Associate Director of Epidemiologic Research at the Department of Research & Evaluation at Kaiser Permanente Southern California. "Our hope is that the findings from our research can help people make treatment decisions that are most consistent with their personal values, preferences and experience."