Research examines safety of treatments for deep vein thrombosis
Patients who have a clot in their legs and are considering whether to be treated with traditional blood-thinning medication or undergo a minimally-invasive catheter-based clot removal procedure should feel comfortable that there is no difference in death rates between the two treatments, although there are more bleeding risks with the catheter procedure, according to a study by Temple University School of Medicine researchers. The study involved a review of more than 90,000 cases nationwide.
Riyaz Bashir, MD, a specialist in interventional cardiology and vascular disease at Temple Heart & Vascular Center, directed the study, which was aimed at figuring out the best way to treat a painful and potentially deadly condition called deep vein thrombosis (DVT).
The study, to be published by JAMA Internal Medicine, compared two approaches: catheter-based thrombolysis, which involves inserting a catheter to deliver clot-dissolving medication directly into the leg clot; and medical therapy using a blood-thinning medication (anticoagulation). The study found that the in-hospital mortality rate was similar for the two groups. However, the catheter-based procedure was associated with higher rates of bleeding. The catheter procedure also was more costly than the medical therapy and involved more days in the hospital.
It is estimated that about 6 percent of DVT patients die within one month of the diagnosis. The study should help inform an ongoing medical debate over the safest and most effective way to treat DVT, which is the third most common cause of cardiovascular morbidity and death after coronary artery disease and stroke. When a blood clot develops in a vein in the leg, it can break loose and travel to the lungs, causing a deadly condition called pulmonary embolism. DVT, which occurs in about 1 out of every 1,000 people per year, can have a long-lasting effect on a person's well-being.
About 20 to 50 percent of patients with above-knee DVT will go on to develop a condition called post-thrombotic syndrome (PTS) even when treated with anticoagulation therapy and compression stockings. Patients with PTS experience pain, swelling, itching, skin discoloration and heaviness in the legs, and, in severe cases, skin ulcers.
"These patients can end up very disabled. They sometimes are unable to work and they lose their job," said Dr. Bashir, Associate Professor of Medicine. "Post-thrombotic syndrome places a huge economic burden ($2.4 billion and 200 million work days lost annually in the U.S.) on the health-care system."
Several studies had shown that early removal of the clot using catheter-directed thrombolysis (CDT) leads to a significant reduction in the incidence of PTS along with improvement in patients' quality of life. The studies were too small, however, to draw any conclusions about the safety of the catheter-based procedure versus medical therapy alone using blood-thinning medications, and doctors are divided on which approach is better. The American Heart Association recommends the catheter-based procedure (CDT) as the first-line therapy for patients at low risk for bleeding, while the American College of Chest Surgeons recommends against the use of CDT because of safety concerns and the complexity of the procedure.
Dr. Bashir and his research team used a national database called Nationwide Inpatient Sample to study outcomes for patients who were hospitalized for DVT between January 2005 and December 2010. They identified 90,618 cases overall. They then compared 3,594 patients who underwent the catheter-based procedure to deliver clot-busting medication to the same number of patients who received anticoagulation alone.
Among the findings were:
- The in-hospital mortality rate was not significantly different between the two groups — 1.2 percent for those who received the catheter procedure, versus those who got medical therapy alone.
- The rate of blood transfusion (a measure of bleeding) was 11.1 percent for the catheter group, versus 6. 5 percent for the medical group.
- The rate of pulmonary embolism (clot in the lung) was 17.9 percent versus 11.4 percent.
- The rate of intracranial hemorrhage (bleeding in the brain) was 0.9 percent for the catheter group versus 0.3 percent for the medical therapy group.
- The length of hospital stay was longer for those patients who had the catheter procedure – 7 days versus 5.1 for the other group.
- Hospital charges were also higher in the catheter group: $85,553 versus $29,369.
The researchers found that rate of CDT utilization for treating DVT went from 2.3 percent in 2005 to 5.9 percent in 2010. Over that same period, the mortality rate for patients who had CDT went down, which is probably a reflection in a refinement in catheter based technologies and increased operator experience. However the rate of bleeding continued to remain higher in this group of patients. Patients who had the procedure at a higher-volume center tended to do better, the study found.
Dr. Bashir said that some patients with DVT clearly benefit from the catheter based procedure, but he said patients needed to be carefully selected. His team concluded that more research is needed to sort out the risks versus the benefits of the procedure.
"In light of the findings of this study, it is imperative that the magnitude of benefit from CDT has to be substantiated in order to justify the increased upfront resource utilization and bleeding risk of this therapy," the researchers wrote. "In the absence of such data, it may be reasonable to restrict this form of therapy to those patients who have a low bleeding risk and have a high risk of PTS," such as patients with clots at or above their groins.
"I think all patients with leg clots should be informed about the risks of developing PTS and its consequences and the risks of catheter-based clot removal so that they can truly participate in shared decision-making," Dr. Bashir said.