Economic motivation could underlie some ordering of imaging tests

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Study finds closer look needed at highest ultilization rates

A new study by researchers at Institute for Technology Assessment in Massachusetts General Hospital’s (MGH) Department of Radiology finds that  physicians who consistently refer patients to themselves or members of their  own specialty for imaging studies, rather than to radiologists, are more  likely to order such studies for a variety of medical conditions.  The  results suggest that economic motivation could underlie some of the excess  referrals.

“It’s looking like a significant part of the increase  in imaging utilization is due to self- and same specialty referral,” according to G.  Scott Gazelle, MD, MPH, PhD, director of the Institute for Technology  Assessment, who led the study being published in the November issue  of Radiology.  

“We need to have some mechanism in place to control this sort of  inappropriate utilization of imaging,” Gazelle said.

Potential conflicts of interest in imaging studies have  been of concern for several decades, leading to the passage in the 1990s of  laws restricting some forms of self-referral – physicians’ ordering tests that  they will be reimbursed for interpreting.  Some earlier studies found  that self-referral  was associated with higher utilization of imaging  studies.  Other studies that documented a greater number of imaging  studies being performed by non-radiologists were not able to distinguish  whether that increase was due to differences in referral patterns or to  increased numbers of non-radiologists offering such procedures. 

The current study was designed to retrospectively  examine how frequently physicians ordered imaging studies for outpatients  treated for specific medical conditions and if that varied depending on  whether the studies were performed by radiologists or by members of the  referring physician’s own specialty, who could be colleagues in the same  practice. 

The researchers analyzed data from a nationwide,  employer-based health plan with around 4 million members:  employees at  all levels, their dependents and retirees.  They identified pairings of  six common medical conditions – cardiopulmonary disease, heart disease, arm or  leg fracture, knee pain or injury, abdominal malignancy, or stroke – with a  diagnostic imaging procedure, and compiled information on each physician who  had seen at least six patients in one or more of those condition/imaging  pairings in the years 1999 to 2003. 

The  investigators analyzed every imaging referral and categorized the physicians  according to their referral patterns.  For purposes of this study, they  compared only those physicians who referred all patients to themselves or  members of their own specialty for imaging studies with those physicians who  always referred to radiologists. 

Results showed that, depending on  the condition/imaging pairings, those making self- or same-specialty referrals  were from 12 percent to more than 200 percent more likely to order an imaging  procedure than were physicians referring to radiologists. “Some  of those who self-refer will say that their patients are sicker, but we found  that controlling for the effect of patients’ age and additional health  conditions made the likelihood of imaging among self- or same-specialty  referrers even stronger – more than 300 percent in some conditions,” study leader Gazelle said.  

He continued: “Others may claim to be offering greater convenience for patients, but  when we looked specifically at CT and MR studies, less than 20 percent were  carried out on the same day as the referring physician visit, which means the  procedures should not be considered part of an office visit but rather  separate visits specifically for the purpose of imaging.”

Gazelle notes that the range of variation in imaging utilization among same-specialty referrers was much greater than among  radiologist referrers.  “It’s not that everyone is overutilizing imaging;  but some appear to be, and we need to take a look at those with the highest  rates of utilization.  We also need to consider whether the self-referral  laws, which currently exempt most procedures offered in physicians’ own  offices, need to be toughened,” he said.   

Gazelle is a professor of Radiology at Harvard Medical  School and a professor in the Department of Health Policy and Management at  Harvard School of Public Health. The study’s co-authors are Elkan Halpern,  PhD, Heather Ryan, MSc, and Angela Tramontano, MPH, all of the MGH Institute  for Technology Assessment and Department of Radiology. 

The study was  funded, in part, by the American College of Radiology.