CHICAGO, Dec. 8 (Xinhua) -- Not all patients with blood clots in their legs need to receive powerful but risky clot-busting drugs, according to results of a large-scale, multicenter clinical trial by researchers at Washing University in St. Louis.
The findings were published on Dec. 7 in the New England Journal of Medicine.
The study involved 692 patients, randomly assigned to receive blood thinners alone or blood thinners and the procedure. Each patient was followed for two years.
In the procedure, doctors insert a thin, flexible plastic tube through a tiny incision in the leg and navigate it through the veins using X-ray and ultrasound guidance, until it rests within the clot. They instill a drug known as tissue plasminogen activator through the tube, give it time to digest the clot and then suck out or grind up any remaining fragments using specialized catheter-mounted devices. The procedure is expensive, costing thousands of dollars, and often requires a hospital stay.
The clinical trial showed that routine use of the procedure did not reduce the chance of developing post-thrombotic syndrome. The complication developed in 157 or 47 percent of 336 people who underwent the procedure and 171 or 48 percent of 355 people who did not, a difference that is not statistically significant.
The procedure did reduce the severity of post-thrombotic syndrome, easing patients' long-term symptoms. About 24 percent of people on blood thinners alone experienced moderate to severe pain and swelling, but only 18 percent of people who were treated with blood thinners and clot busters did so.
The procedure also alleviated pain and swelling in the early stages of the disease, when patients are often very uncomfortable.
But, the researchers noted a worrisome increase in the number of people who developed major bleeding after undergoing the procedure. In comparison, while one patient or 0.3 percent on standard treatment experienced a bleed, six or 1.7 percent of those who received clot-busting drugs experienced a bleed.
"What we know now is that we can spare most patients the need to undergo a risky and costly treatment," said principal investigator Suresh Vedantham, a professor of radiology and of surgery at Washington University School of Medicine in St. Louis.
While the study showed that most patients should not undergo the procedure, the data hint that the benefits may outweigh the risks in some patients, such as those with exceptionally large clots.
Between 300,000 and 600,000 people in the United States are diagnosed with a first episode of deep vein thrombosis a year, and despite standard treatment with blood thinners, roughly half will develop post-thrombotic syndrome. There is no treatment to prevent the potentially debilitating complication.