By Lisa Blackwell
Magnetic resonance imaging, or MRI, is often used to diagnose low back pain. MRIs can be useful if there are warning signs that suggest a more serious problem.
A new study showed that patients who got an MRI immediately after a back injury had more doctor visits, physical therapy and higher medical bills than patients who waited to have an MRI.
Instead, the study suggested that doctors should follow current medical guidelines, waiting approximately six weeks in most cases to order an MRI.
Earlier studies have shown that most cases of low back pain resolved themselves within a month.
Janessa Graves, PhD, MPH, from the Harborview Injury Prevention and Research Center at the University of Washington, and colleagues conducted this study to estimate the value of having early MRIs for work-related low back pain.
These researchers used a database of medical bills to identify 1,770 patients over the age of 18 who had filed worker compensation claims related to their low back between 2002 and 2004.
The researchers got medical records and costs from the date the injury occurred through one year later. They determined whether the patients were disabled or recovered one year later.
The patients were divided into two groups: those who got an MRI according to medical guidelines (no MRI before six weeks) and those who got MRIs earlier than medical guidelines recommend.
The researchers compared medical treatments and costs, as well as pain and disability, of the patients who got an early MRI to the patients who did not get an early MRI.
The study found 336 patients (about 19 percent of the patients) who had an MRI early. These patients ended up receiving 52 to 54 percent more medical treatments than the patients who did not receive an MRI earlier than medical guidelines recommend.
The treatments included physical and occupational therapy, lumbosacral epidural injections (pain medication given to the spine through a needle) and surgery.
Approximately 30 percent of the patients who received an MRI early had a lumbar radiograph, which is a kind of x-ray, within one year of injury, compared to 18 percent of patients who did not have an early MRI.
The average medical costs for the group who had an early MRI were more than twice the costs for the group with no early MRI.
Medical guidelines recommend waiting at least six weeks before ordering an MRI for low back pain.
The researchers said the excess costs associated with treatments after having an early MRI are quite substantial. The authors did not know the cause for the additional medical treatments and expense. One possibility is that an early MRI may start a series of health care services.
The researchers noted that it may be possible that patients who have early MRIs also have characteristics that make them more likely to have additional medical services. It is also possible that the patients who had MRIs early had more severe injuries than the patients who did not have early MRIs. The researchers tried to account for this possibility, but it may have affected the results nonetheless.
One strength of this study was that it followed a large group of people with a good deal of medical information.
But the study also had weaknesses, such as including only patients in Washington state with worker compensation claims. This could mean that the findings of the study do not apply to patients with injuries that are not work-related. As the researchers did not see the MRI images, they could not know outcomes of the treatments, or whether the care received was effective.
The authors noted that it is possible their findings were impacted by something they did not measure in the study. The study also did not find out why the doctors had ordered the MRIs early, so there may have been severe injuries needing additional treatment.
They also noted the injuries of the participants in the study were not very similar. Some of the patients had injuries that quickly resolved, while others needed lengthy ongoing treatments. This made the groups hard to compare.
The authors referred to several other studies by different researchers that also found no improved outcomes from early MRIs. These prior studies suggested that early MRIs were not likely to improve pain, functioning or health status compared to recommended treatment.
This study was published August 1 in Health Services Research.
The research was funded by the National Institute for Occupations Safety and Health, the Agency for Healthcare Research and Quality, the National Institutes of Health and the National Institute of Child Health and Human Development. The authors declared no conflict of interest.