WEDNESDAY, Oct. 14 (HealthDay News) -- Having easy access to MRI scans may be a bad thing for people with new-onset lower back pain, according to U.S. researchers.

The analysis of 1998-2005 Medicare data found that patients with new pain in their lower back were more likely to have surgery if they were treated in an area that had a higher-than-average concentration of MRI (magnetic resonance imaging) machines.

The researchers projected that if all Medicare patients with new-onset lower back pain lived in areas with the least MRI availability in 2004, there would have been 5.4 percent fewer lower back MRIs and 9 percent fewer back surgeries.

The study authors also found that two-thirds of MRI scans that may have resulted from increased MRI availability took place within the first month of onset of back pain. However, clinical guidelines recommend delaying an MRI scan until four weeks after onset, during which time most people with low back pain show improvement.

"Not only are patients in high-availability areas getting more MRIs, but they are getting them earlier," study first author Jacqueline Baras, a Stanford University medical student, said in a university news release.

While this may sound good, it's actually a cause for concern. Previous research found that increased surgery rates don't improve outcomes for patients with new-onset low back pain.

"The worry is that many people will not benefit from surgery, so heading in this direction is concerning," senior author Laurence Baker, a professor of health research and policy, said in the release.

"It is important that policymakers recognize that infrastructure matters, and that the number of MRI machines in any particular area may affect the volume and quality of health care that patients receive," Baras said.

The study was published online Oct. 14 in the journal Health Affairs.

More information

The U.S. National Institute of Neurological Disorders and Stroke has more about low back pain.