Evidence-based healthcare management

Clinical guidelines for the management of back pain could increase the use of radiology

Suarez-Almazor M E, Belseck E, Russell A S, Mackel J V. Use of lnmbar radiographs for the early diagnosis o f low back pahz: proposed guidelines would hicrease utilization. JAMA 1997; 277:1782-1786

Objective

To evaluate the potential impact of guidelines for the management of patients with new episodes of low back pain.

Setting

Four primary-care clinics in Alberta, Canada.

Method

Retrospective cohort study; 963 patients who had lumbar spine X-rays during their first visit; the charts of these patients were reviewed, allowing a minimum follow-up time of 2 years. Patients with vertebral fractures, tumours and spinal infections were identified at the follow-up.

Literature review

No explicit strategy; 30 references.

Results

A total of 1550 patients had had a new episode of low back pain, of whom 963

(62%) had back pain that met the definition in the guidelines. 127 (13%) of the 963 patients had a lumbar spine X-ray at the initial visit, 68 patients having oblique views in addition.

44 (35%) of the 127 spinal X-rays were normal. 64 had degenerative changes, four patients had a fracture, and in one patient a diagnosis of possible cancer was made.

Using the guidelines that had been recommended, the proportion of patients that would have had a lumbar spine X-ray would have increased to 44%, an increase in utilization of 238%. On review of the patients' records, 8 of the 963 patients were diagnosed as having serious disease that would have been present at the time of the X-ray, 3 with cancer and 5 with a fracture. 4 of these 8 patients had not had a lumbar spine X-ray at the time of their presentation. 2 of these 4 patients had a previous history of compression fractures of the lumbar spine, one had cancer diagnosed 2 months after the initial low back pain visit, and the fourth had multiple myeloma, a cancerous change in the bone marrow, detected in a further X-ray 3 months later.

© Harcourt Brace and Company Ltd 1998

Authors ' conclusions

The authors report other studies, including decision analysis, that demonstrate that the probability of encountering severe disease requiring specific therapy by giving spinal X-ray to all patients with low back pain is between 1 and 2 in I000.

The guidelines, if used, would have had a 100% sensitivity in the diagnosis of spinal tumour or compression fracture. The gain in sensitivity would, however, have been accompanied by a decrease in specificity, with a marked increase in utilization in patients without these disorders; the specificity would be 56% if the guidelines were used, whereas the physician's judgement had a specificity of 87%. The use of guidelines that explicitly discouraged the use of oblique X-rays could, however, have had significant impact on cost and the amount of radiation received by the public because more than half of the patients who had lumbar spine X-ray also had oblique views. The authors conclude that with a higher sensitivity guidelines 'maY improve the prompt diagnosis of potentially serious diseases'. Evidence that the detection of compression fractures or spinal tumours, which are usually either secondary tumours from cancers elsewhere or a generalized type of bone-marrow tumour called multiple myeloma, would have any beneficial impact on progflosis or treatment outcome is still uncertain. Furthermore, they point out that any gains achieved for a small proportion of patients would only be achieved with a substantial increase in costs and increased radiation, for they quote an estimate that a million extra lumbar spine X-rays can result in 20 excess deaths from leukaemia and 400 excess cases of genetic disease.

:OMMENTAR~

Differences in the world-wide practice of medicine are well exemplif ied by this article. The guidelines issued by the Agency for Health Care Policy and Research in the USA, which these authors model in primary practice in Canada, would be thought somewhat quaint in the modern NHS within the UK. UK radiologists never adopted routine obl ique radiographs. Indeed workers here, where radiation and cost are even larger issues, have shown that even routine AP radiographs are of l imited value if the lateral v iew is normal. I Furthermore, as long ago as 1995, UK guidelines suggested that X-rays of the

lumbar spine were 'not indicated routinely' for back pain; 2 the adverse features that justified imaging are mucfi more restricted than those in the USA. Future UK guidelines wil l suggest even less plain radiography of the lumbar spine and recommend more magnetic resonance imaging (MRI) - a technique that provides greater diagnostic and therapeutic impact 3 at no radiation risk a.nd wi th only marginal extra cos t . 4 Perhaps an even more controversial recommendation in patients w i th no adverse features would be to wi thhold all forms of imaging unti l conservative measures have failed. "l'his would overcome the most harmful potential effect of imaging, namely inappropriate

intervention for an asymptomatic lesion. The prevalence of inevitable 'degenerative changes' and asymptomatic disk disease s bedevils algorithmic approaches to imaging of the lumbar spine. Perhaps the real decision should lie wi th the physician, who only has to ask the straightforward question: is the patient ill? Even simple tests, such as the erythrocyte sedimentation rate, wi l l help identi fy most patients wi th important disc space infections or tumour.

What this paper does show is that carefully designed guidelines, which are effectively promulgated, carry the potential to influence practice - up to a point. In this case, they may have increased referral. More commonly,

98 EVIDENCE-BASED HEALTH POLICY AND MANAGEMENT DECEMBER 1998

Clinical gttidelines for the managenlent of back pain I

guidelines wil l reduce inappropriate referrals for a while after dissemination; practice can then be audited; reminders can be sent if necessary. All this wil l contribute to making the best use of radiological departments. 2 Those in charge of imaging facilities have a responsibility to ensure that the right patients are examined by appropriate techniques in a timely foshion. Guidelines provide one method of assisting this process. However, this paper reminds us ~.hat guidelines developed by one health care system may not always be applicable in another.

References

1. Padiey S, Gleeson F, Chisholm R, Baldwin J. Assessment of a single lateral lumbar spine radiography in low back pain. BrJ Radio11990; 63:535-536 Making the best use of a Department of Clinical Radiology: guidelines for doctors, 3rd edn. London: Royal College of Radiologists, 1995 Dixon A K, Southern J P, Teale A et al. Magnetic resonance imaging of the head and spine: effective for the clinician or the patient. BMJ 1991; 302:79-82 Jarvik G J, Maravilla K R, Haynor D R, Levltz M, Deyo R A. Rapid MR imaging versus ptain

2.

3.

4.

radiography in patients with low back pain: initial results of a randomised study. Radiology 1997; 204:447-454

5. Wiesel S W, Tsourmas N, Feffer H L, Citrin C M, Patronas N. A study of computer assisted tomography. 1. The incidence of positive CAT scans in an asymptomatic group of patients. Spine 1984; 9:549-551

Professor Adrian Dixon Department of Radiology

University of Cambridge School of Clinical Medicine

Cambridge, UK

DECEMBER 1998 EVIDENCE-BASED HEALTH POLICY AND MANAGEMENT 99