THURSDAY, Jan. 31 (HealthDay News) -- More than half the patients in hospitals worldwide risk developing dangerous blood clots known as venous thromboembolisms, yet many aren't receiving treatments that could prevent the condition, a large international study shows.

"Venous thromboembolism has long been recognized to be one of the most common avoidable causes of death associated with hospital stay," said study co-author Dr. Ajay Kakkar, a professor of surgical sciences at Barts and the London School of Medicine and Dentistry in the United Kingdom. "What was interesting from this study was how commonly risk factors for blood clots are found in patients admitted to hospital and the variations in the provision of preventative measures."

The study, published in the Feb. 2 issue of The Lancet, covered 358 hospitals in 32 countries and included all hospital inpatients over 40 admitted to a medical ward and those aged 18 or over admitted to a surgical ward.

Participants were assessed for VTE risk based on a review of their hospital charts.

Out of a total of 68,183 patients, only 58.5 percent of at-risk surgical patients and 39.5 percent of at-risk medical patients received recommended preventive treatments.

The consistency of risk reported throughout the countries studied was surprising, according to the study's lead author, Dr. Alexander Cohen, an honorary consultant and vascular physician at King's College London.

But, he added, "the great variation in prevention use and the fact that all countries were suboptimal, with the U.K. somewhere in the middle, were not surprising."

In the study, the proportion of at-risk medical patients receiving the appropriate treatment varied by country, with Germany (70 percent), Spain (64 percent) and Colombia (64 percent) rating the highest, and Bangladesh (3 percent), Thailand (4 percent) and Romania (18 percent) at the bottom.

In the United States, 48 percent of at-risk medical patients received the appropriate care.

Germany scored the highest for at-risk surgical patients (92 percent), along with Hungary (87 percent) and Spain (82 percent). Bangladesh and Thailand (both 0.2 percent) were the low rankers again, along with Pakistan (10 percent). In this category, the United States scored 71 percent.

VTE can result in blockage of blood vessels in the leg (deep vein thrombosis) or a pulmonary embolism, the blockage of a lung artery that can sometimes be fatal.

VTE is common during and after hospitalization, and is considered the most common preventable cause of in-hospital death. Studies have linked pulmonary embolism to up to 10 percent of in-hospital sudden deaths.

Guidelines for prevention of VTE in hospitals have been available for more than 15 years, yet are underused. Such treatments include blood-thinning drugs, as well as pneumatic compression and compression stockings.

According to an accompanying commentary in the journal, preventive medications can reduce the risk of pulmonary embolism by 75 percent in general surgical patients and by 57 percent in medical patients.

One U.S. expert agreed that steps can be taken to reduce the danger to patients. Dr. Joel Horovitz, director of the division of general surgery at Maimonides Medical Center in New York City, noted that some hospitals are using a computer-order entry system in which all hospital orders have to be recorded on the computer, not written.

"At our hospital, doctors can't escape that screen, so 97 percent of patients admitted to surgery are prescribed prophylaxis," he said.

But a recent study of U.S. hospital patients found that, despite these guidelines, half the patients were not getting preventive treatment for VTE.

"Identifying those at risk of developing a blood clot is straightforward and should happen at the time of hospital admission. For those at risk, preventative measures should be initiated immediately," Kakkar said.

More information

The National Heart, Lung, and Blood Institute has more on blood clots.

SOURCES: Ajay Kakkar, M.D., Ph.D., professor, surgical sciences, Barts and the London School of Medicine and Dentistry, U.K.; Alexander (Ander) Cohen, MBBS, M.D., honorary consultant, vascular physician, King's College London, U.K.; Joel Horovitz, M.D., director, division of general surgery, Maimonides Medical Center, New York City, Feb. 2, 2008, The Lancet

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