Better Prevention for Deadly Blood Clots

Published in Hopkins Medicine - Spring/Summer 2021

Based on a systematic review of scientific studies dating back nearly 70 years, a team from Johns Hopkins and collaborating institutions suggests that ambulation is not sufficient alone as a preventive measure against venous thromboembolism (VTE), a condition that can result in potentially deadly pulmonary embolisms.

VTE annually affects some 300,000 to 600,000 individuals in the United States, and kills between 60,000 to 100,000 of those stricken, according to the U.S. Centers for Disease Control and Prevention. Among the groups at highest risk are hospitalized patients, especially those who undergo surgery.

Since the 1950s, ambulation (in the form of walking or foot/leg exercises) as soon and as often as possible following surgery has been recommended as a means of reducing the threat of VTE in high-risk patients. The latest study was conducted to see if ambulation is enough or if other measures — primarily anticoagulants — are needed.

“Our systematic review revealed little evidence to support ambulation alone as an adequate means of preventing VTEs,” says Johns Hopkins’ Elliott Haut, senior author of the study, which appeared in the Canadian Medical Association Journal Open. It reviewed nearly 21,000 scientific papers from 1951 through April 2020 and used predefined scoring criteria to select the 18 most relevant studies.

The findings are concerning, Haut says, because ambulation is commonly thought to be effective as the sole prophylaxis used to avoid VTEs. In fact, he adds, several national and international clinical guidelines recommend this course of action.

“It’s a mistaken belief that often leads to doctors discontinuing what they perceive as unnecessary medication or nurses presenting ambulation as an alternative prophylaxis to patients,” says study lead author Brandyn Lau, of the Department of Radiology and Radiological Science at Johns Hopkins. “On the contrary, there is overwhelming evidence supporting medications to prevent VTE in nearly every applicable population admitted to a hospital.”