Rheumatology Advance Access originally published online on March 27, 2006
Rheumatology 2006 45(7):920-921; doi:10.1093/rheumatology/kel102
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LETTER TO THE EDITOR |
Red flags need more evaluation
University of Sydney, Back Pain Research Group, Lidcombe, NSW, Australia
Correspondence to: N. Henschke. E-mail: N.Henschke{at}fhs.usyd.edu.au
SIR, The recent review on the role of physiotherapy in the management of non-specific back pain and neck pain [1] failed to highlight a large deficit in the evidence-base of low back pain management. Whilst the review draws upon high-quality evidence to make recommendations for treatment, this was not the case when recommendations were made on the use of ‘red flags’ to screen for serious pathology. Practitioners were encouraged to use the list of red flags provided in Table 1 to screen for serious pathology. Readers were advised that if any red flag is found, a prompt referral to a specialist for further investigation needs to be arranged. However, readers should be advised against uncritical acceptance of this recommendation.
It seems to have gone largely unnoticed that there is little or no high-quality evidence on the diagnostic accuracy of red flags and that on the limited evidence available, some red flags seem to have little diagnostic power. In our view, this situation has probably arisen because the guidelines that have promoted the red flags (e.g. the recent European Guidelines [2]) have relied upon secondary citation [3] or referred to studies [4] which did not seek to assess the diagnostic accuracy of the features. The dangers of secondary referencing are well-known and are particularly evident here, with perhaps the most important part of the clinical examination becoming orthodoxy without any supporting data. As an example, Moffett and McLean's review [1] and many other guidelines promote thoracic pain as a red flag; however, the only study that evaluated this clinical feature reported a positive likelihood ratio of 1.1 and a negative likelihood ratio of 1.0, indicating that this feature has no value in screening for serious spinal pathology [5].
Leaving aside the uncertainty about the diagnostic accuracy of red flags, Moffett and McLean's [1] suggested approach to diagnostic triage may not be feasible in many health care settings. Moffett and McLean [1] advocate that if any of the 12 red flags in Table 1 are present the patient should be referred to a specialist. Deyo and Diehl [5] showed that requiring any of the four red flags to be positive (age >50, or a history of cancer, or unexplained weight loss, or failure of conservative therapy) detected all cases of cancer; however, there was a false alarm rate of 40%. Based upon Deyo and Diehl's [5] data, Moffett and McLean's [1] strategy is likely to detect all cases of cancer; however, it will have an even higher high false alarm rate and so will probably create unmanageable workloads for specialists. A better strategy for primary care may be that described by Jarvik and Deyo [6], where if any red flags are positive plain radiographs and simple blood tests such as erythrocyte sedimentation rate (ESR) are first ordered as an intermediate step before considering the need for more advanced imaging or specialist review.
In our view, the current body of low back pain research is unbalanced because there has been too little research evaluating the accuracy of the red flags. For example, while there are 564 clinical trials of physiotherapy treatments for low back pain [7], there are only a handful of studies that have evaluated screening for cancer with red flags. Without high quality data on the accuracy of the red flag questions, recommendations on their use in routine clinical practice cannot be confidently made. Further high quality studies in primary care settings are obviously needed as the accuracy of the diagnostic tests used in physiotherapy is as important as data regarding the effectiveness of management strategies.
Nicholas Henschke is under scholarship funded by the University of Sydney and the National Health and Medical Research Council of Australia.
References
- Moffett J, McLean S. The role of physiotherapy in the management of non-specific back pain and neck pain. December 6, 2005. Rheumatology 10.1093/rheumatology/kei242.
- Tulder M, Becker A, Bekkering T et al. European guidelines for the management of acute nonspecific low back pain in primary care. 2004.
- Waddell G, Feder G, McIntosh A, Lewis M, Hutchison A. Low back pain evidence review. London: Royal College of General Practitioners, 1996.
- Waddell G. An approach to backache. Br J Hosp Med 1982;28:187.[Medline]
- 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.[Web of Science][Medline]
- Jarvik JG, Deyo RA. Diagnostic evaluation of low back pain with emphasis on imaging. Ann Intern Med 2002;137:586–97.
[Abstract/Free Full Text] - PEDro: http://www.pedro.fhs.usyd.edu.au (accessed 24/01/2006).
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