Red Flags

 

“Referring patients for imaging based on the presence of a single red flag, is not warranted.” – Downie et al. 2013

Red flags are a widely accepted method for identifying the existence of serious pathology such as malignancy, infection or  fracture. The use of red flags in a LBP presentation, is to assist in identifying patients with a higher likelihood of spinal fracture, infection or malignancy in order to appropriately refer these patients for further extensive diagnostic investigations [1].

What we now know is that up to 80% of patients presenting in primary care with acute lower back pain may have at least one red flag present, whilst less than 1% have a serious underlying pathology related to their back pain [2]. The majority of cases of LBP in the general population are self-limited and benign.

For example, spinal infection and cauda equina syndrome, while critical to identify, are so rare that many primary care practitioners may never encounter them [2].

Whilst we must remain vigilant in identifying red flags, referring patients for imaging based on the presence of a single red flag, is not warranted.

For instance, up to 50% of LBP cases report night pain [3] which has previously been considered a red flag for malignancy or infection. However, given the minute percentage of LBP presentations that have a malignancy or infectious cause, referring patients for further diagnostic imaging in the presence of a single red flag such as night pain, is unnecessary.

The negative effects of imaging must be also considered when deciding whether diagnostic imaging is warranted [4]. These include:

  • Invasive diagnostic procedures
  • Patient fear and anxiety
  • Poorer outcomes
  • Cost
  • Radiation exposure

The infographic below highlights the signs of potential red flags in LBP. Further high-quality research is needed to extensively evaluate the accuracy of red flags and the combinations of red flags in order to assist health care providers in identifying those most in need for imaging.

Full credit to SquareOnePhysiotherapy for the original article on red flags in low back pain.

FRACTURE

The red flags with the highest post-test probability for detection of a fracture are listed below. The probability of spinal fracture is higher when multiple red flags are present [5].

  • Older age
  • Prolonged use of corticosteroid drugs
  • Severe trauma
  • Presence of a contusion or abrasion

SPINAL MALIGNANCY

The single red flag with the highest post-test probability for detection of spinal malignancy is a history of malignancy [5].

While several other red flags are endorsed in guidelines to screen for fracture or malignancy, only the small subset presented above have evidence for diagnostic utility. Evidence for the accuracy of other recommended red flags is lacking [6].

  1. Downie, A., Williams, C. M., Henschke, N., Hancock, M. J., Ostelo, R. W., de Vet, H. C., . . . Koes, B. W. (2013). Red flags to screen for malignancy and fracture in patients with low back pain: systematic review. BMJ, 347, f7095.
  2. Grunau, G. L., Darlow, B., Flynn, T., O’Sullivan, K., O’Sullivan, P. B., & Forster, B. B. (2018). Red flags or red herrings? Redefining the role of red flags in low back pain to reduce overimaging. British Journal of Sports Medicine, 52(8), 488-489. doi:10.1136/bjsports-2017-097725
  3. Henschke, N., Maher, C. G., Refshauge, K. M., Herbert, R. D., Cumming, R. G., Bleasel, J., . . . McAuley, J. H. (2009). Prevalence of and screening for serious spinal pathology in patients presenting to primary care settings with acute low back pain. Arthritis Rheum, 60(10), 3072-3080. doi:10.1002/art.24853
  4. Darlow, B., Forster, B. B., O’Sullivan, K., & O’Sullivan, P. (2017). It is time to stop causing harm with inappropriate imaging for low back pain. British Journal of Sports Medicine, 51(5), 414-415. doi:10.1136/bjsports-2016-096741
  5. Downie, A., Williams, C. M., Henschke, N., Hancock, M. J., Ostelo, R. W., de Vet, H. C., . . . Koes, B. W. (2013). Red flags to screen for malignancy and fracture in patients with low back pain: systematic review. BMJ, 347, f7095.
  6. Verhagen, A. P., Downie, A., Popal, N., Maher, C., & Koes, B. W. (2016). Red flags presented in current low back pain guidelines: a review. Eur Spine J, 25(9), 2788-2802. doi:10.1007/s00586-016-4684-0