Low Back Pain: How Helpful is an MRI?

It’s not often that I am in agreement with health insurance companies but they seem to be getting one thing right as of late. We have noticed an increase in patient’s referred to our clinics for low back pain that have not undergone advanced diagnostic imaging techniques, such as MRI. It appears that large insurance companies are denying authorization for these MRI’s until the patient has undergone a course of physical therapy (more on the topic). Physical therapists are certainly on board with these decisions but some of our patients are often confused or annoyed by their insurance company dictating their care. So, should patients with an acute onset of low back pain undergo routine MRI or undergo a course of physical therapy first? Why not be safe and undergo the MRI first? How can a physical therapist offer treatment without knowing what the problem or diagnosis is?

Physical Therapy or MRI First?

A recent study published in the journal Health Services Research investigated this question. Researchers found that those patients seeking primary care services for low back pain and were referred for an early MRI underwent higher health care utilization at increased costs compared to those receiving early physical therapy. The additional cost of receiving the MRI first was nearly $5000 more than receiving early physical therapy. Earlier research studies show that consulting a physical therapist early results in decreased odds of undergoing diagnostic imaging (here) and decreased odds of undergoing future surgery for low back pain (here). Delaying physical therapy has also been associated with increased prescription opioid (narcotic pain medication) use and most of us are aware of how big of an epidemic this is becoming (more here).

Why Not Play it Safe and Undergo the MRI First?

A 2003 study in the Journal of the American Medical Association compared the use of early MRI vs. early x-ray for patients with a new episode of low back pain. One year later, pain levels and disability were no better in those undergoing the MRI. Of note, the group receiving the early MRI was more likely to undergo back surgery. This is not surprising given the high likelihood of pathological findings in asymptomatic subjects (no low back pain) who undergo advanced diagnostic imaging. A 2015 systematic review reported the prevalence of disc degeneration in asymptomatic individuals ranged from 37% of 20-year olds to 96% of 80-year olds. Similar rates were reported for asymptomatic disc bulges. If so many people without low back pain have these findings on MRI we cannot confidently conclude that these findings are the true cause of symptoms. Making erroneous assumptions based on MRI findings often leads to over treatment. The more testing and treatment a patient undergoes the more likely factors such as fear and anxiety come into play and these are the factors that have been associated with persistent or chronic low back pain.

Physical Therapy Treatment without Imaging

MRI or further medical work up is always indicated in situations where serious pathology is suspected or when response to initial treatment is poor. However, low back pain emanating from serious pathology has been estimated to occur in less than 2 percent of cases. Doctor’s of physical therapy are trained in screening for these signs and when there are any suspicions of non-musculoskeletal problems prompt referral is indicated. In most cases these problems are ruled out based on a detailed interview and medical history. Physical therapists then base their examination and treatment on the individual patient’s signs and symptoms; not based on a diagnosis or MRI scan. Physical therapists are concerned with how movement affects symptoms and how symptoms affect movement.

In most cases of low back pain delaying the MRI is the best approach.