While other factors may be at play, the finding builds on growing evidence for the role of financial incentives in physician behavior and the impact that this behavior may have on soaring healthcare expenditures in the U.S.
"In the same patient, a medical problem would be evaluated -- and perhaps treated -- differently by employed versus self-employed urologists," Dr. John M. Hollingsworth, of the University of Michigan Medical School in Ann Arbor, Michigan, who led the new study, told Reuters Health in an e-mail.
While the volume of their work doesn't affect the salary of most employed physicians, the self-employed can take home extra cash by taking on additional patients or ordering more diagnostic tests, he and colleagues point out. And with declining real-dollar incomes, this source of new revenue may be particularly alluring for some physicians.
The researchers looked at more than 37 million outpatient visits to urologists across the U.S., using data from the National Ambulatory Medical Care Survey conducted in 2006 and 2007. Four out of every five physicians surveyed were self-employed.
Overall, more than one in five urology visits resulted in imaging, they report.
Most of the imaging was indicated for a benign enlargement of the prostate, kidney stones, or the presence of blood in the urine. Of the various imaging tests, urologists usually chose ultrasound.
This use of diagnostic testing did not vary by factors such as the patient's age, gender, or Medicaid eligibility, nor by the doctor's practice type or location.
Self-employed urologists, however, were nearly twice as likely to order imaging compared to employed urologists: 24.2% versus 13.2% (p < 0.001).
Profit motivations may be one of the forces driving this difference. But other possibilities exist, Dr. Hollingsworth noted, including patient preference, legal concerns, and intolerance of medical ambiguity.
Regardless of the underlying reason, the practice could lead to unintended consequences for patients, including a modest increase in radiation exposure and overdiagnosis of "pseudodisease," Dr. Hollingsworth added.
The use of imaging has been on the rise in recent years, along with advances in the technologies behind the tools.
"With physicians controlling much of the demand for imaging, strategies to affect its use should consider the methods by which providers are compensated," Dr. Hollingsworth said.
He added that these findings have direct relevance to some of the healthcare reform measures in the Affordable Care Act of 2010.
"Under the new healthcare law," Dr. Hollingsworth told Reuters Health, "the Center for Medicare and Medicaid Innovation is charged with testing new reimbursement models, which include varying payment to physicians who order advanced diagnostic imaging services as defined according to the physician's adherence to appropriateness criteria of such services."
"It will be interesting to see how such a change will impact utilization among self-employed and employed urologists," he said.
By Lynne Peeples
J Urol 2010.
Last Updated: 2010-11-05 17:37:21 -0400 (Reuters Health)
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