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Am Fam Physician. 2004;69(3):639-640

Early magnetic resonance imaging (MRI) for low back pain might lead to rapid diagnosis and effective treatment, but it also may identify abnormalities unrelated to the patient's symptoms. Jarvik and colleagues conducted a randomized trial that compared costs, benefits, and patient outcomes with radiography versus MRI as an initial diagnostic test in patients with low back pain.

The authors recruited 380 eligible patients. After completing questionnaires related to pain and functional status, patients were assigned randomly to radiography or MRI of the lumbar spine. Certain patients, such as those for whom additional views had been ordered, were excluded from the trial. The primary outcome measure was the modified Roland back pain disability scale, which measures the effect of back pain on activities of daily living. This scale was administered three, six, and 12 months after imaging, with the hypothesis that patients who received MRI would have better scores than those diagnosed by radiography. Secondary outcomes included back pain frequency and bothersomeness according to the Medical Outcomes Study 36-Item Short Form Health Survey. Preference scores and time–trade-off technique measures were assessed. The authors also conducted an economic analysis that included office visit costs, alternative health care consultations, medication use,hospitalization,back-pain–related time, and transportation.

The study was completed by 167 participants in the MRI group and 170 in the radiography group. There was no statistically significant difference between the groups in the 12-month Roland scale score. The radiography group had a score of 8.75 compared with a score of 9.34 in the MRI group. Both groups had significant clinical improvement, especially in the first three months, with no significant differences between groups according to many measures. The satisfaction score relating to the degree of reassurance patients received from imaging, however, differed between the groups, with patients consistently rating reassurance from the MRI results higher than that for the radiography results, although this difference was small. At 12 months, 58 percent of those receiving radiography versus 74 percent of those receiving MRI responded that their test results reassured them.

Patients randomized to radiography had approximately twice the total number of physical therapy, acupuncture, massage, osteopathic, or chiropractic appointments, whether initiated by physician or patient, compared with the MRI group. Because more MRI patients underwent surgery, the cost of care was higher in the MRI group, although this difference was not statistically significant. In terms of cost-effectiveness, MRI is more costly than radiography with clinically equivalent outcomes, but there appears to be wide variation. Therefore, it is difficult to make definitive statements about the economic effects of these different imaging approaches.

Overall, MRI resulted in no improvements over radiography in terms of disability, pain, or general health status. Patients and physicians preferred MRI. Because MRI does not appear to cause harm or increase costs substantially, and is reassuring to patients, it is difficult to recommend for or against it, even though it does not improve patients' symptoms and functional outcomes.

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