Fran Lowry

December 09, 2010

December 9, 2010 (Chicago, Illinois) — The use of computed tomography (CT) scans in emergency departments (EDs) throughout the United States has increased dramatically in recent years, and this increase shows little signs of slowing, according to a study presented here at the Radiological Society of North America 96th Scientific Assembly and Annual Meeting, and published online November 30 in Radiology.

From 1995 to 2007, the number of visits in which a CT scan was performed increased 6-fold, from 2.7 million to 16.2 million, representing a growth rate of 16% per year, said David B. Larson, MD, MBA, from Cincinnati Children's Hospital Medical Center in Ohio.

"This increase is potentially concerning, given the questions about the safety of radiation exposure and increasing healthcare costs," he told Medscape Medical News.

The percentage of visits that were associated with a CT scan also increased substantially, from 2.8% of all visits in 1995 to 13.9% of all visits in 2007, Dr. Larson said.

He and his team examined data from the Centers for Disease Control and Prevention's National Hospital Ambulatory Medical Care Survey, which collects data on approximately 30,000 emergency visits each year.

CT use was greater in older patients, white patients, patients admitted to the hospital, and in hospitals located in urban areas. Toward the end of the study period, most CTs were for abdominal pain, headache, and chest pain.

According to Dr. Larson, it is not just the magnitude of the growth in CT scanning that is so striking, but the nature of that growth. "When you look at the model of how technology diffuses in a population, it usually starts with accelerating growth and then, after a period of time, it begins to decelerate and taper off. But the use of CT scans is still in the acceleration phase, at least in 2007. It hasn't even started to taper by this time period, so we've seen very rapid, steady, and sustained growth."

He added that there is no question that in the setting of a life-threatening injury or severe illness, a CT is appropriate. "The real question is when an indication is less clear, where there is less severe illness. At what point do you draw the line and say no to CT? It is such a great test, it is an excellent modality, and in some ways it's harder to make the decision not to do it."

Increase in CT Scans Might Not Be a Bad Thing

Elliot K. Fishman, MD, professor of radiology, surgery, and oncology at Johns Hopkins Hospital in Baltimore, Maryland, believes it is important to put this increase in the proper perspective.

"When you first look at this study, there is a tendency to say: 'Oh dear, we've got increased volume. This must be terrible.' But I think for a lot of the volume increases there are very good reasons," he told Medscape Medical News.

"If you look at those years, it was an era when CT was really moving into the [emergency department]. People were finally getting scanners in the [emergency department]. Before that, the scanner was in the hospital, and this made it difficult to schedule an exam. So the ability to get a scan when you needed it in the emergency setting became much more common."

This period was also one of rapid growth in terms of CT technology, Dr. Fishman noted. "We went from basically 4 slice, to 16, to 64. So it wasn't like the technology stood still."

CT also came to be used in place of other tests for ruling out common reasons for visits to the emergency department, such as pulmonary embolism and appendicitis.

"It became very common in the [emergency] setting to use CT to rule out pulmonary embolism. Before the advent of CT, this was done by nuclear medicine," Dr. Fishman noted. "This study does not address whether CT replaced anything, but it is very probable that some of the CT scans are replacing other tests; they didn't just fall out of the sky and start being used for no reason," he said.

Abdominal pain is a common complaint in emergency departments, and CT scans can rule out appendicitis. "These days, the percentage of people who go to surgery with a negative appendix is well under 5%, whereas it used to be 20% to 30%. Stone disease is another common cause of abdominal pain, and CT can rule that out. This is another of the true growth areas in CT, and here it was probably replacing plain films and [intravenous pyelograms]."

Another area of true growth for CT is in triage.

"CTs in the [emergency] setting are really good triage tools," said Dr. Fishman. "We used to keep people in the [emergency department] for 12 to 24 hours to observe them, but with CT, if you suspect something, you go in and scan the patient and if there is nothing there, you discharge the patient. So CT, because of its high positive and negative predictive value, makes it easy to do rapid triage. In this cost-conscious era, it is very cost effective."

Dr. Fishman said he is not surprised to learn that growth of CT was so rapid from 1995 to 2007. But he believes that now, such growth has plateaued. "From 2007 to 2010, I would say, those curves have flattened. Here at Hopkins, our volumes are probably down about 7% to 10%."

Dr. Larson and Dr. Fishman have disclosed no relevant financial relationships.

Radiology. Published online November 30, 2010. Abstract

Radiological Society of North America (RSNA) 96th Scientific Assembly and Annual Meeting: Abstract SSCO7-09. Presented November 29, 2010.