It was reported by the Clinical Standards Advisory Group (CSAG)1 in 1996 that although serious pathology is indeed very rare, better outcomes are achieved if they are identified early in their disease process.
They reported diagnostic triage in back pain as follows:
- Simple Backache (95% of cases)
- Nerve root pain (<5% of cases)
- Serious pathology (<1% of cases).
While serious pathology is rare, it does not want to be missed should it arise.
Part of the uncertainty surrounding the identification of red flags is that when we actually look at the research, the 'so called' red flags in and of them selves really do not tell us very much.
In a 2016 review of the literature Verhagen and colleagues2 looked at the red flags used for serious spinal pathology in low back pain across twenty-one international guidelines published between 2000 and 2015.
This review found forty-six red flags associated with the four main categories of serious pathology which include:
- Cauda equina
Red flags, are prognostic variables used to identify if a symptom could be part of a presentation suggestive of serious pathology and require referral for further investigation (Greenhalgh & Selfe, 2010)3. In a 2007 clinical guideline on physiotherapy management (CSP 2007) they actually identified one-hundred-and-nineteen items in the subjective history and forty-four in the objective history as red flags. In an attempt to clarify and sharpen all these items into a more concise guideline Roberts et al. (2007)4 then surveyed the development group for agreement on individual red flags. The results were grouped according to the following:
- 100% agreement = unanimity
- 75-99% agreement = consensus
- 51-74% agreement = majority view
- 0-50% agreement = No consensus
Not a single red flag reached unanimity across the development group. The guidelines however did report eleven items that were consistent across more than 50% of the papers reviewed:
Consensus (75-99% agreement):
- Weight loss
- A history of cancer
Majority View (51-74% agreement):
- Night pain
- Age >50
- Violent trauma
- Saddle Anaesthesia
- Difficulty with micturition
- Intravenous drug misuse
- Progressive neurology
- Systemic steroids
While these findings are very much a general indication of serious pathology, the Verhagen et al. (2016)2 review found that some red flags are more suggestive for specific pathology than others. They suggested that a history of cancer and unexplained unintentional weight loss were the best indicators of malignancy (cancer). It was reported that 'major trauma' and 'use of steroids or immunosuppressors' were most predictive of fracture. Fever, steroids and intravenous drug abuse best predicted infection and saddle anaesthesia / bowel and bladder dysfunction for cauda equina.
Downie et al. (2013)5 concluded in a systematic review of this literature that only a few red flags were actually informative. While this is where red flag research is currently at, it must be noted that the conclusions of these reviews / guidelines are based on consensus, with hardly any guidelines presenting the evidence for endorsing red flags.
Greenhalgh and Selfe (2010)3 describe the approach for navigating red flags via an index of suspicion. In their 'Guide to Solving Serious Pathology of the Spine' they present a hierarchical list of red flags based on the best available evidence that simply must be coupled with clinical reasoning on the practitioners part to give more or less weight to any given 'red flag'. The importance of the clinician to execute clinical reasoning cannot be underestimated and is largely the reason that diagnostic triage cannot be efficiently done via a software or online format.
The updated hierarchy has been included below. For more detail on each element and how to reason that particular flag, clinicians are heavily advised to purchase the guide and read it themselves - a red flag checklist simply does not tell us enough.
Greenhalgh & Selfe (2010) Hierarchical list of Red flags
- Age >50 years + history of cancer +unexplained weight loss + failure to improve after 1 month of evidence-based conservative therapy
- Age<10 and >51 years
- Weight loss >10% body weight (3-6 months)
- Severe night pain precluding sleep
- Loss of sphincter tone and altered S4 sensation
- Bladder retention or bowel incontinence
- Positive extensor plantar response
Medical history (current or past) of:
- Human immunodeficiency virus (HIV / acquired immune deficiency syndrome (AIDS) or intravenous drug use
- Age 11-19
- Weight loss 5-10% body weight (3-6 months)
- Constant progressive pain
- Band like pain
- Abdominal pain and changed bowel habits, but with no change of medication
- Inability to lie supine
- Bizarre neurological deficit
- Disturbed gait
- Loss of mobility, difficulty with stairs, falls, trips
- Legs misbehave, odd feelings in legs, legs feeling heavy
- Weight loss <5% body weight (3-6 months)
- Systemically unwell
- Bilateral pins and needles in hands and / or feet
- Previous failed treatment
- Thoracic pain
- Physical appearance
- Marked partial articular restriction of movement
Red herrings that can often lead to misinterpretation of red flags include:
1. Misattribution by:
- the patient
- the referring doctor or allied health professional
- the treating clinician
2. Inappropriate overt illness behaviour
3. Widespread pain systems dysfunction
4. Other conditions that complicate the clinical scenario but which do not impact on the management of the patient
5. Biomedical masqueraders
Luke R. Davies :)
1. Clinical Standards Advisory Group (CSAG): 1996: Back Pain and Epidemiology Review: The Epidemiology and Cost of Back Pain: Clinical Standards Advisory Group (Committee Chaired by Michael Rosen). Her Majesty's Stationery Office, London, 1994.
3. Greenhalgh, S. and Selfe, J. (2010). Red Flags II: A guide to Solving Serious Pathology of the Spine, CPI Group Ltd, Croydon, UK
4. Roberts, L., Fraser, F. and Murphy, E. A. (2007). What is a Red Flag? World Confederation of Physical Therapy, Vancouver - Cited In Greenhalgh and Selfe, 2010 P.38
5. Downie, A., Williams, C. M., Henschke, N., Hancock, M. J., Ostelo, W. J. G., De Vet, H. C. W., Macaskill P., Irwig, L., Van Tulder, M. W., Koes, B. W and Maher, C. (2013). Red Flags to Screen for Malignancy and Fracture in Patinets with Low Back Pain: Systematic Review, British Medical Journal, 347, doi: 10.1136/bmj.f7095.