Scan Technology Tied to Overtreatment of Clots in Lungs

MONDAY May 9, 2011 -- Overdiagnosis and overtreatment of pulmonary embolism is a problem in the United States due to the large increase in the use of computed tomography pulmonary angiography (CTPA), a new study suggests.

A pulmonary embolism (PE) is a potentially life-threatening blood clot in the lungs. CTPA was introduced in 1998 to improve detection of PE and its use has grown rapidly, according to background information in the study by Boston University School of Medicine researchers.

The investigators compared data about PE in U.S. adults before (1993-1998) and after (1998-2006) CTPA was introduced, and found that the incidence of PE increased 81 percent after CTPA became available, from 62.1 to 112.3 per 100,000 people.

Deaths from PE decreased during both time periods, but more so before (8 percent reduction, from 13.4 to 12.3 per 100,000), than after the introduction of CTPA (3 percent reduction, from 12.3 to 11.9 per 100,000 people), the research team reported.

There was also a slight improvement in case fatality before CTPA (8 percent decrease, from 13.2 to 12.1 percent of patients) and a substantial improvement after CTPA (36 percent decrease, from 12.1 to 7.8 percent of cases), according to the report published in the May 9 issue of the Archives of Internal Medicine.

While CTPA offers many benefits, the downside is that it can detect clots so small that they might never cause symptoms or death, yet the treatment for these clots, known as anti-clotting therapy, may be harmful to patients, the researchers said.

"Overdiagnosis matters because it can lead to [treatment-related] harm. While a clinically insignificant PE is by definition not harmful, treating such an embolism can cause harm such as bleeding from anticoagulation [anti-clotting therapy], which can -- in the worst case -- be fatal," lead author Dr. Renda Soylemez Wiener, an assistant professor of medicine, said in a university news release.

The frequency of presumed complications of anticoagulation for PE was stable before CTPA, but increased 71 percent (from 3.1 to 5.3 per 100,000) after CTPA became available, the study authors explained.

The problem of overdiagnosis and overtreatment of PE is likely to continue to grow, according to the study authors. They called for further research to determine whether some PE patients with small clots can safely forgo anticoagulation treatment.

More information

The Society for Vascular Surgery has more about pulmonary embolism.

Posted: May 2011


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