Despite efforts, medical imaging use continues to climb

Medical imaging use continues to climb despite efforts to curb overutilization of CT, MRI and other modalities, according to the results of a new 16-year study examining more than 135 million exams performed in the U.S. and Canada.

The study, published Sept. 3 in the JAMA, found that the growth in imaging did level off in the early 2000s, but has shot back up recently for CT and MRI among most patients. One bright spot was the decline in CT use in children, reported lead author Rebecca Smith-Bindman, MD, a UCSF professor of radiology, epidemiology and biostatistics, and obstetrics and reproductive medicine.

"Our capture of medical imaging utilization across seven U.S. health care systems and Ontario, Canada, over a 16-year period provides one of the most comprehensive assessments to date of imaging in children to older adults in North America," said Marilyn Kwan, PhD, co-author and senior research scientist in the Kaiser Permanente Northern California Division of Research, in a prepared statement.

Lead investigator Smith-Bindman and colleagues noted that imaging undoubtedly improves treatment, but can also increase costs and patient harm related to incidental findings, overdiagnosis and radiation exposure. Additionally, the researchers wrote, some estimate nearly 30% of exams are unnecessary—approximately $30 billion annually in the U.S.

“Like all aspects of medicine, it's important to make sure imaging is justified, and that the potential benefits are balanced against the potential harms," Smith-Bindman said in a news release. "These potential harms of false positive diagnoses and overdiagnoses can impact everyone who undergoes a test and thus need to be considered when imaging is used."

For their study, the researchers looked at the use of medical imaging between 2000 and 2016 among 16-21 million adult and pediatric patients across seven U.S. healthcare systems and in Ontario, Canada. U.S. data was included for those who received care in fully integrated healthcare systems and those with “mixed insurance” including HMOs and PPOs with fee-for-service coverage.

Overall, annual growth in CT, MRI and ultrasound peaked from 2000-2006, but has risen year over year. And between 2012 and 2016, the team found 1-5% annual growth in utilization amongst most age groups and tests in the U.S. and Canada.

Additional results are below:

  • CT use in children fell in the U.S. from 2009-2013 and has held steady since then. In Ontario, utilization has decreased since 2006.
  • Nuclear medicine exams decreased across all age groups and in both settings between 2000 and 2016.
  • While CT and MRI utilization is higher in the U.S., the disparity is closing.
  • In most cases, rates of imaging jumped right after they fell. For example, growth in CT exams among older patients was 9.5% in 2000-2005, fell by .9% in 2006-2011, then increased to 3% annual growth until 2016.

Efforts such as the “Choosing Wisely” campaign launched in 2012, which was endorsed by 85 professional medical societies, and financial incentives designed to reduce overutilization have not adequately achieved their intended goal, according to the authors.

"Although most physicians are aware that imaging tests are frequently overused, there are not enough evidenced-based guidelines that rely on a careful consideration of the evidence, including information on benefits and harms that can inform their testing decisions," Smith-Bindman said. "In the absence of balanced evidence, the default decision is to image."