Current issues of ACP Journal Club are published in Annals of Internal Medicine


Diagnosis

Review: Diagnostic accuracy is problematic for low-back pain

ACP J Club. 1995 July-Aug;123:18. doi:10.7326/ACPJC-1995-123-1-018


Source Citation

van den Hoogen HM, Koes BW, van Eijk JT, Bouter LM. On the accuracy of history, physical examination, and erythrocyte sedimentation rate in diagnosing low back pain in general practice. A criteria-based review of the literature. Spine. 1995 Feb 1;20:318-27.


Abstract

Objective

To determine the accuracy of history taking, physical examination, and erythrocyte sedimentation rate (ESR) in diagnosing the cause of low-back pain.

Data sources

A MEDLINE search was done (1986 to 1992) using the terms backache or low back and sciatica, cancer, or spondylitis; and bibliographies of retrieved studies were reviewed.

Study selection

Studies were selected if they provided data on the sensitivity or sensitivity and specificity of history taking, physical examinations, and ESR for radiculopathy, vertebral cancer or metastasis, and ankylosing spondylitis. Reviews and studies with < 10 patients were excluded. 540 studies were retrieved; 36 met the inclusion criteria.

Data extraction

2 reviewers independently rated each study in 9 categories, including application and quality of the index and diagnostic standard tests, study population characteristics, sample size, and data interpretation. The maximum attainable score was 100. Sensitivity and specificity were calculated.

Main results

Of the 36 studies identified, 19 were of radiculopathy, 9 were of vertebral cancer or metastasis, and 8 were of ankylosing spondylitis. 34 studies were hospital based. The mean total score for all studies was 55 points (range 20 to 85 points). Only studies with points above the mean were reviewed for diagnostic accuracy. Straight leg raising (SLR) was useful for excluding radiculopathy {negative likelihood ratio [LR] range 0.04 to 0.54}*; crossed SLR was useful for including radiculopathy {positive LR range 1.9 to 7.2}*. Spinal tenderness was the only sign tested in all 4 included studies for vertebral cancer; however, the results were markedly inconsistent {positive LR range 0.4 to 3.5, negative LR range 0.3 to 1.4}*. In 1 study, history of previous cancer {positive LR, 15.5}* was useful in diagnosing vertebral cancer. Among studies of ankylosing spondylitis, history items and elevated ESR were more accurate predictors of disease than physical examination.

Conclusion

The diagnostic accuracies of individual items of history taking, physical examination, and erythrocyte sedimentation rate are poor for predicting radiculopathy, vertebral cancer or metastasis, and ankylosing spondylitis.

Sources of funding: Dutch Organisation for Scientific Research and Health Insurance Executive Board.

For article reprint: Dr. H. van den Hoogen, Lepelaar 13, S721 DN Asten, The Netherlands.

*Numbers calculated from data in article.


Commentary

Clinicians do not use single tests to rule in or rule out serious causes of low-back pain, and this study supports this practice. Unfortunately, little information exists on the diagnostic value of the combination of clinical data, including time course and response to conservative therapy. A good study (1) of 1975 outpatients with low-back pain found that cancer could only be excluded (100% sensitivity; LR = 0) if none of the following was present: age > 50 years, history of cancer, unexplained weight loss, and failure of conservative therapy.

van den Hoogen and colleagues found that most of the studies they reviewed used such poor methods that their results were either invalid or unreliable; even studies with relatively high quality scores could be fatally flawed, often because of spectrum, referral, or work-up bias. All 19 studies of radiculopathy, for example, involved hospitalized patients only, which probably means that the reported specificities are falsely low.

In the algorithm recently proposed by the AHCPR Acute Low Back Pain Guideline Panel (2), which also critically assessed prevention, treatment, and the value of more expensive tests, any one of several red flags for fracture, tumor, infection, or the cauda equina syndrome would prompt further immediate evaluation. Patients not found to have any of these conditions would be treated conservatively; for example, the absence of sciatica would exclude consideration of a herniated disc. Clearly, better studies are needed to clarify the value of these diagnostic tests.

Arthur T. Evans, MD, MPH
University of North CarolinaChapel Hill, North Carolina, USA
Jerry D. Joines, MD
Moses H. Cone Memorial HospitalGreensboro, North Carolina, USA


References

1. Deyo RA, Diehl AK. Cancer as a cause of back pain: frequency, clinical presentation, and diagnostic strategies. J Gen Intern Med. 1988;3:230-8.

2. Bigos S, Bowyer O, Braen G, et al. Acute Low Back Problems in Adults: Assessment and Treatment. Clinical Practice Guideline, Quick Reference Guide Number 14. Rockville, MD: U.S. Department of Health and Human Service, Public Health Service, AHCPR Pub. No. 95-0643, December 1994.