It's one thing when a doctor orders a test to find the cause of a patient's problem. It's entirely another when that test is ordered despite the doctor knowing it's probably not needed.

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But for one-third of MRI scans done in patients with lower back pain, that's exactly what appears to be going on. Despite many efforts to discourage physicians from ordering such scans except under certain circumstances, including the Choosing Wisely campaign, patients continue to get costly screenings.

A new study may help answer the question of why. Erika Sears, M.D., M.S., and her colleagues from the University of Michigan Medical School recently published their findings in JAMA Internal Medicine.

The team completed a random sample of nearly 580 physicians, nurse practitioners and physician assistants across the Department of Veterans Affairs. The researchers asked whether and why the practitioners would order an MRI or CT scan for a hypothetical 45-year-old female patient with lower back pain but no "red flag" symptoms, and how they thought the patient would respond.

Sears discusses the study below.

What did the research find?

Sears: Our study showed that almost all clinicians were aware that an imaging test was not indicated for a patient with low back pain without danger signals of severe spinal problems. Almost all agreed with the Choosing Wisely recommendations to not do testing — only 3 percent thought a CT or MRI would benefit this patient.

Instead, clinicians worried about not having sufficient time to explain the risks and benefits of testing to patients, were concerned over medical liability if tests are not ordered or rare diagnoses are missed.

Many (75.7 percent) noted that they cannot refer patients to specialists without first ordering imaging, even if they think the imaging will not change patient management.

Our study showed that these concerns exist, but future studies are needed to determine if these perceptions actually lead to use of inappropriate imaging.

Why are there so many inappropriate low back imaging scans, then?

Sears: Overuse of diagnostic tests is a common problem in health care as a whole, and affects both the VA and private-sector settings. Low back pain is often highlighted because it is a common condition where overuse of imaging or treatments can consume a high level of resources.

There are many complicated factors that can lead to overuse of imaging. Many interventions to reduce inappropriate testing have tried to improve provider knowledge to make sure the correct type of test is performed, and to not order tests if the results will not change treatment decisions.

What happens if this kind of imaging is overused?

Sears: When patients get imaging tests they do not need, they are subject not only to unnecessary costs and wasted time for appointments and time away from work and family, but also potentially to harm.

For example, tests like CT scans expose the patient to radiation, which can add up over time. And the test a patient didn't need could expose an incidental finding that may be insignificant to a patient's health but lead to more downstream testing, and sometimes complications. More than three-quarters of our respondents said they would worry about this in the case we presented to them.

Unnecessary testing is not just bad for the individual patient getting the test, it is bad for all of us. The excess costs of unnecessary tests mean that all of our insurance premiums might get raised.

And a system bogged down with unnecessary tests may provide slower access to necessary testing, as it is impossible to triage tests based on their overall necessity.

How can providers target the use of such screening more appropriately?

Sears: We know from research which patients benefit from imaging tests for low back pain, but we don't always have the tools to apply that knowledge to everyday practice.

Health systems need to have strategies that help clinicians confirm that a test is not necessary, and then to address additional demands on clinicians, such as limited time to explain the risks and benefits to patients and policies that prohibit referral to specialists without prior imaging.

Patients may insist on the need for imaging for low back pain. What can providers do?

Sears: Some patients may not fully understand when test results do and do not impact treatment decisions. It also seems that patients who have medical problems that are associated with unpleasant symptoms, such as pain, are more likely to request imaging.

SEE ALSO: To Screen or Not to Screen: Risks of Over-Imaging and Testing

Our study showed that more than half the providers worried that the hypothetical patient would become upset if they didn't order imaging for her condition. Nearly two-thirds said they thought it would be hard for most patients in the hypothetical situation to accept the Choosing Wisely standard and go without a scan.

If providers had sufficient time and tools to counsel patients of the risks and benefits of diagnostic tests, then some patients may be more willing to not have imaging.

So what should lower back pain patients receive?

Sears: Several professional societies recommend not ordering imaging for patients with low back pain when the pain has been present less than six weeks, if no "red flag" symptoms are present. Those are exam findings that indicate a serious spine problem.

The American College of Physicians takes this recommendation one step further to not recommend imaging for patients with nonspecific low back pain, even beyond the first six weeks. This is because imaging does not relate to improved patient outcomes.

Patients should first have a thorough history and physical exam to rule out presence of "red flag" symptoms, and should be referred to physical therapy in the initial treatment period. Almost all of them will have at least some improvement after this initial time period. Because low back pain tends to come back, staying active — through activities such as walking, yoga and supervised training — is key to warding off recurrence. Some patients with recurrent nonspecific back pain may require a referral to a pain specialist.