More MRI scanners lead to excess back surgeries

Patients with low back pain have a greater chance of undergoing surgery that may not help if they live in an area that has more magnetic resonance imaging machines, a study of Medicare recipients found.

Those in regions with the highest concentration of MRI scanners were about 20 percent more likely to have back surgery than those who lived in an area with the lowest concentration, research online in the journal Health Affairs showed. Back surgery isn't proven or recommended to help patients with nonspecific low back pain, the study authors said.

The number of MRI machines tripled in the U.S. to 26.6 machines per 1 million people in 2005 from 7.6 machines per million people in 2000, according to the article. Medicare, the U.S. government health program for the elderly, pays about $600 for a lower back scan, the researchers said. An increase in the number of scans and surgeries is raising the cost of treating lower back pain, according to the study authors.

"Patients for a long time in this country had engrained in them that getting more stuff is better for you," said study author Laurence Baker, a professor of health research and policy at Stanford University near Palo Alto, Calif. "More scanning did not make it better, it might make you worse and get you surgery that doesn't really work."

MRIs use a magnetic field, radio frequency pulses and a computer to produce detailed images of the body.

The researchers looked at data from a 20 percent sample of Medicare recipients who received care for low back pain from 1998 to 2005 in 318 metropolitan areas. They linked the patient data with the number of MRI machines in each area. Those in the highest availability areas had at least two times as many MRI machines per capita as those in the lowest availability areas, the authors said.

The study included 666,455 episodes of low back pain. Almost 16 percent of the episodes led to an MRI and 2.7 percent resulted in low back surgery within a year of first visiting the doctor.