Kaiser Permanente Study Finds Blood-Thinning Bridge Therapy May Be Harmful for Patients at Low to Moderate Risk for Blood Clots

News provided by

May 26, 2015, 11:00 ET

DENVER, May 26, 2015 /PRNewswire/ -- Patients with a history of blood clots are commonly prescribed warfarin, an anticoagulant, to decrease the body's ability to form additional clots. Clinicians typically stop the use of this drug in patients to reduce the risk of serious bleeding when invasive procedures, such as colonoscopies or orthopedic surgeries are scheduled. However, when warfarin interruptions occur, patients are exposed to an increased risk of blood clots three to five days before and five or more days after invasive procedures. Bridge therapy with another, faster acting anticoagulant is often initiated in an attempt to reduce the patients' risk for developing blood clots during that gap. A new study published today in JAMA Internal Medicine finds that this treatment may actually create more risk than benefits.

"Bridging has been a part of standard therapy for venous thromboembolism or VTE patients undergoing invasive procedures for many years," said lead study author Nathan Clark, PharmD, clinical pharmacy supervisor, anticoagulation and anemia management services, Kaiser Permanente Colorado. "The increased risk of bleeding coupled with the low-risk of VTE recurrence for these patients indicate this therapy may be unnecessary and potentially harmful for that patient population."

Venous thromboembolism includes two related conditions: deep vein thrombosis, which is a blood clot that occurs in a deep vein of the body, and pulmonary embolism, which occurs when a clot breaks free and enters the arteries of the lungs, according to the Centers for Disease Control and Prevention.

Before this study, only limited data outlining the rates of bleeding and VTE recurrence were available to help clinicians analyze the risks and benefits of bridge therapy. Kaiser Permanente researchers examined the electronic medical records of 1,178 patients with VTE who underwent 1,812 invasive diagnostic or surgical procedures between January 2006 to March 2012 that required the interruption of warfarin therapy.

Study patients were categorized into three groups based on their annual risk of VTE recurrence without anticoagulant therapy. Within those groups, a total of 555 patients – 28.7 percent of low-risk, 33.6 percent of moderate-risk and 63.2 percent of high-risk patients – received bridging anticoagulant therapy. The 1,257 patients who did not receive bridge therapy interrupted their warfarin use and received no other anticoagulants during the perioperative period. The use of bridge therapy resulted in a 17-fold higher risk of bleeding without a significant difference in the rate of blood clot formation compared to patients who didn't receive bridge therapy. In addition, there were no significant differences in the rates of blood clot occurrence or death between the bridged and non-bridged patient groups.

Among patients in this study, the rate of clinically relevant bleeding in the bridged group was 2.7 percent compared to 0.2 percent in the non-bridged group. Clinically relevant bleeding was defined as bleeding occurring within 30 days of the procedure that resulted in hospitalization, emergency room admission or procedure-related complications.

According to Clark, further research is needed to identify patient and procedure-related characteristics associated with the highest risk for perioperative VTE recurrence where targeted bridge therapy during warfarin interruption may be beneficial.

Through its highly coordinated integrated care delivery system, Kaiser Permanente is committed to furthering understanding of available therapies to prevent and treat blood clots. In 2012, a Kaiser Permanente Colorado study, in collaboration with investigators from the Cancer Research Network, found that the use of low molecular weight heparin to treat patients with advanced cancer complicated by blood clots increased steadily from 2000–2007. Also, according to a 2012 Kaiser Permanente Colorado study published in the Archives of Internal Medicine, not resuming warfarin therapy within 90 days of a gastrointestinal bleeding event related to that therapy is associated with an increased risk of blood clots and death.

This new study was conducted and funded by Kaiser Permanente Colorado in partnership with the Kaiser Permanente Colorado Pharmacy Department; University of Colorado Anschutz Medical Campus, Skaggs School of Pharmacy and Pharmaceutical Sciences; University of Utah College of Pharmacy; Denver Health Medical Center, La Casa Quigg Newton Clinic; Pacific University School of Pharmacy; McMaster University, Department of Medicine; and the State of Colorado, Department of Health Care Policy & Financing.

Additional study authors include: Daniel M. Witt, PharmD, Loren E. Davies, PharmD, Edward M. Saito, PharmD, Kathleen H. McCool, PharmD, James D. Douketis, MD, Kelli R. Metz, PharmD, and Thomas Delate, PhD.

About Kaiser Permanente Colorado
Kaiser Permanente Colorado is the state's largest nonprofit health plan, proudly working to improve the lives and health of Colorado residents for more than 45 years. Kaiser Permanente Colorado provides comprehensive health care services to 630,000 members through 29 medical offices and a network of affiliated hospitals and physicians. Kaiser Permanente was recognized by the National Committee for Quality Assurance (NCQA) as the top-ranked commercial health plan in Colorado and the sixth ranked Medicare plan in the nation for 2014-15. Kaiser Permanente was also recently recognized as a 2012 Hypertension Champion by Million Hearts™. In 2014, Kaiser Permanente proudly directed $100 million to community benefit programs to improve the health of all Coloradans. For more Kaiser Permanente news, visit kp.org/share or follow us on Twitter @kpcolorado or facebook.com/kpcolorado.

About Kaiser Permanente
Kaiser Permanente is committed to helping shape the future of health care. We are recognized as one of America's leading health care providers and not-for-profit health plans. Founded in 1945, Kaiser Permanente has a mission to provide high-quality, affordable health care services and to improve the health of our members and the communities we serve. We currently serve more than 10 million members in eight states and the District of Columbia. Care for members and patients is focused on their total health and guided by their personal physicians, specialists and team of caregivers. Our expert and caring medical teams are empowered and supported by industry-leading technology advances and tools for health promotion, disease prevention, state-of-the-art care delivery and world-class chronic disease management. Kaiser Permanente is dedicated to care innovations, clinical research, health education and the support of community health. For more information, go to kp.org/share.

For more information, contact:
Navneet Miller, [email protected], 415-262-5972
Nick Roper, [email protected], 303-344-7619

Logo - http://photos.prnewswire.com/prnh/20130718/SF49717LOGO

SOURCE Kaiser Permanente