What causes increasing and unnecessary use of radiological investigations?

Ask this question of someone in the U.S. radiology community and I'm willing to bet the answer will be spoken a bit louder than the question was asked. The premise is insulting-although apparently not to radiologists in Norway, or so I have been led to believe.

This week Kristin Lysdahl and Bjørn Hofmann from the University of Oslo globally released results from their survey of Norwegian Medical Association members who practice radiology. They asked 537 such members about potential causes of increased and unnecessary radiological investigations. About 70% (375) replied.

In tallying their responses, the researchers claim they have found the top five reasons for unnecessary overuse of radiological imaging tests. The reasons were reported this week in the online-only open-access journal BMC Health Services Research:  

• Increased possibilities due to new radiological technology; 
• Patients' increased demands for certain knowledge about their own health; 
• Referring physicians' lower tolerance for uncertainty; 
• Expanded clinical indications for radiology; and
• Increased availability of radiological equipment and personnel.

"Overutilization implies wasteful investigations, such as those whose results are unlikely to affect patient management," Lysdahl said. "Because some investigations carry risks from radiation exposure and many can be expensive to the health service, it is important to limit their excessive use."

Who can argue with such a statement? The problem is that this statement, like the premise of the survey, is based on the assumption that excessive utilization is a substantial problem and that radiologists are at fault. Seeing this, I wondered how Lysdahl and Hofmann elicited such a high response rate to their survey. What I found was a carefully crafted approach, one that sounded unlike the conclusions drawn from the data.

Question one of two stated "The volume of radiological investigations is increasing in Norway. To what extent do you think this may be caused by the following factors?"

Fifteen possible causes were listed. Question two listed the six main causes of unnecessary use of radiological investigations, as noted in the referral guidelines for imaging ("European Commission: Radiation protection 118: referral guidelines for imaging. Luxembourg: Office for Official Publications of the European Communities; 2001), and asked "To what extent do you think this occurs at your workplace?"

Answers to both questions used a five-point response scale (to a very small extent, to a small extent, to some extent, to a large extent, to a very large extent). Table 1, "Radiologists' ratings of the extent to which suggested causes increase the volume of radiological investigations," showed responses ranked in the order of importance with three groupings (i.e., to a larger or very large extent, to some extent, to a small or very small extent). This table ranked all 15 possible reasons. Table 2, "Radiologists' ratings of the extent to which causes of unnecessary investigations occur at own workplace," however, listed only two reasons for overuse cited by more than 40% of respondents as occurring to a large or very large extent at their facilities. After these two, the percentage dropped below 30% for the third and fourth reasons. All four were rooted in decisions made by referring physicians. The fifth was under 10% and the sixth barely registered.

One can argue that any confusion concerning these results can be cleared up by reading the paper. The problem, however, is that not many will actually read the paper, although I suggest going to BMC Health Services Research and doing so.

From the summary of the findings publicly released this week, it's easy to jump to conclusions and draw an even simpler one-that imaging is being overused-when in fact the real question is: why are radiologists being pegged with these kinds of assumptions? Don't expect a survey on this question any time soon.