Low back pain - does it need costly scan?

A major study has been conducted to evaluate the role of Magnetic Resonance Imaging (MRI) and Computed Tomography (CT) scans in the treatment of low back pain (LBP).

The findings of the trial carried out by the University of Aberdeen could lead health care professionals to question whether the cost of MRI and CT scans outweigh the benefits of their use in the management of many patients with this kind of back pain.

The five-year long study involved almost 800 patients from 14 NHS hospitals in Scotland and one in England. Its findings have just been published in the prestigious American journal Radiology.

Patients in the trial had been referred by their GP to a consultant orthopaedic surgeon or neurosurgeon because of symptomatic lumbar spine disorders. The specialist was uncertain of the need for imaging.

Participants were randomly allocated to two groups - one for early imaging (MRI or CT scan as soon as was practical) or delayed, selective imaging (no imaging unless a clear clinical indication developed).

The outcomes of patients were measured in a number of ways - see more background from study below.

The study found that the early use of imaging did not affect the management of patient's healthcare. Participants in the MRI/CT group were found to be marginally better than those who were not scanned.
However researchers do not believe it was a clinically important difference.

Professor Fiona Gilbert, Department of Radiology, School of Medicine at the University, is lead author of the report Does early imaging influence management and improve outcomes in patients with low back pain?

She said: "This large study suggests that MRI does not change clinicians' diagnosis or management of low back pain. It supports the premise that we should restrict MRI to those patients who are having surgery or an intervention where the level of the disc disease needs to be accurately shown."

Low back pain (LBP) is a common reason for health care consultations. Although most bouts are self limiting, up to 20% of patients in the UK are referred to a secondary care specialist. Most patients referred to specialists receive conservative (non surgical) treatment. The role of imaging in treatment of these patients is uncertain, poorly defined and variable. Some clinicians routinely request imaging to confirm their diagnosis and to provide reassurance.

The purpose of the study was to establish whether early use of MRI or CT scans influences treatment and outcome of patients with LBP and whether it is cost-effective.

The study was co-ordinated by the Department of Radiology, the Health Services Research Unit and the Health Economics Research Unit, University of Aberdeen.

Patients were recruited between November 1996 and June 1999 - there had to be clinical uncertainty about the need for imaging. Patients who were excluded from the trial were those who required immediate referral for imaging (eg those who had signs which suggested serious abnormalities or disease, or who required surgical intervention), those who had undergone MR imaging or CT of the spine in the previous 12 months, those who did not need imaging, and those who had pain of a non-spinal origin.

Patient outcomes were measured in a number of ways at trial entry, eight months into the trial and at 24 months. The primary measure was the Aberdeen Low Back Pain (ALBP) score. This was assessed via a questionnaire which allowed assessment of LBP in a number of ways, including pain, physical impairment, and functional disability. Other measures were the SF-36 - a general physical and mental health questionnaire and the Euroqol (EQ-5D) - a questionnaire which generates a score used by health economists to evaluate the increase or decrease in both the quality and quantity of life generated by a healthcare treatment or intervention.

Patients in both groups reported an improvement in health over the two years the trial was conducted, but there was significantly greater improvement in participants in the MRI/CT group - as evaluated by the questionnaires. However researchers question whether there were any real clinical differences.

The study found that there were no significant differences between the two groups in overall clinical treatment, except for the use of imaging and the timing of outpatient appointments. The findings suggest that imaging may have a small direct effect, perhaps through reassurance.

The paper concludes that decisions about the use of sophisticated imaging will depend to an extent on judgements about the value of the observed differences in outcome and whether they are worth the costs of early imaging.

The use of MR imaging does not appear to affect treatment overall, and the small observed improvement in outcome is of questionable clinical importance. Although some researchers may argue that any improvement is worthwhile, given that other costs of treatment do not appear to be increased, others may say that the cost of providing a small improvement in patients' overall well-being is not justifiable, especially when there are competing demands for MR imaging resources.

LBP is one of the most common reasons for GP consultations in the UK - the disability has implications for sufferers, the health services and society in general through work incapacity, sickness and invalidity benefit payments.

It is estimated that there around 6.5 million GP consultations per year for back pain and approximately 1.5 million have an X-ray and more than 100,000 have a CT or MRI scan - the latter is an expensive imaging technique with high capital costs, maintenance, staff and operational costs.

Royal College of Radiologists' guidelines recommend that MRI or CT imaging of lumbar spine should be restricted to specific categories of patients with signs of potentially serious problems or those requiring surgery.

This study was funded by the Health Technology Assessment Programme (project number 93/17/43).
The views and opinions expressed therein are the views of the authors and do not necessarily reflect the Department of Health.

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