Remote Screening for Lumbar Spine Red Flags

Introduction

Clinical findings that increase the level of suspicion that there is a serious medical condition described as red flags (Finucane L. 2020), They are key for patient safety so often a component of clinical guidelines for the assessment and management of people with low back pain (Ferguson, Morison and Ryan, 2015). Red flags are features from a patient's subjective and objective assessment which are thought to put them at a higher risk of serious pathology and warrant referral for further diagnostic testing (Delitto, George, and Godges. 2012).

Physiotherapists understanding of red flags for low back pain

The role of physiotherapists as primary identifiers of red flags has grown owing to the spread of self‐referral services (Holdsworth et al., 2006). Physiotherapists often exists without any medical input or review (Kersten et al., 2007; McPherson et al., 2006). Therefore, there is a need to ensure that physiotherapists have a good understanding of individual red flags, understand their importance, and can ask these questions in a clear and unambiguous manner. Similarly, physiotherapists must have a clear understanding and agreed pathways of care dependent on these findings. Failure to do so raises issues around patient safety and professional reputation.

Epidemiology of Red flags

One study aimed to investigate which red flags do physiotherapists routinely record; which red flags do they consider to be most important; how would they define each red flag; and how they would ask each red‐flag question to a person with back pain (Ferguson, Morison and Ryan, 2015). 98 physiotherapists responded to the survey, 84% worked exclusively in the National Health Service (NHS). They recorded that ‘Previous history of cancer’, ‘saddle anaesthesia’ and ‘difficulty with micturition’ were the red flags with the highest level of importance attached to them to rise suspicion to serious pathologies. Definitions of were as follows, history of cancer: ‘an individual who has previously been diagnosed with cancer’. And Saddle anaesthesia: Since your symptoms commenced, have you noticed any pins and needles or numbness around your back passage or genital area’. Finally, limited consensus was found in how physiotherapists asked patients about red flags. However, one theme in ponticular emerged, which is the use of nebulous terminology - for example, the terms recent, weight loss and prolonged period.

Cauda Equina

Cauda Equina Syndrome (CES) is a challenging condition to diagnose and manage. It may present at any time or in any setting and it is imperative that clinicians are able to quickly reason through their findings to manage the patient effectively. There are many causes of CES, but the most common cause is that of a lumbar spine disc herniation and it occurs most frequently between the ages of 31–50 (Fuso et al., 2013). CES compression usually occurs as a result of a disc prolapse, often at the L4/5 level (Fraser et al., 2009). However, any space-occupying lesion, such as spinal stenosis, tumour, cysts, infection, or bony ingress can narrow the spinal canal and cause compression of the CES.

In 1994, The Clinical Standards Advisory Group suggested that serious pathology comprised just 1% of all back pain, with CES being just one of the many serious conditions that can lead to back pain (Verhagen et al., 2016). Despite CES being estimated to have a very low prevalence, it is considered to be a major problem internationally and multiple National Guidelines for the management of low back pain refer to the importance of screening for CES (Verhagen et al., 2016). CES red flags

The presence of red flags may indicate underlying CES in patients with low back pain. Current guidelines often present a list of red flags, which are considered to be associated with an increased risk of the presence of CES, often without consideration given to the diagnostic accuracy of the red flag. While most guidelines recommend screening for red flags, there is variation in which red flags are endorsed, and there exists heterogeneity in precise definitions of the red flags.

Malignancy

The spinal cord may be compressed due to tumours occupying space within the vertebral canal (Gilbert et al. 1978). This may then affect the neural function of the spinal cord causing unremitting pain, muscle power and sensation alteration, sexual dysfunction, bladder/bowel dysfunction and sleep disturbances (cancerresearchuk.org, 2020).

Epidemiology

Tumours are classified as primary, originating in the spine, and secondary, originating elsewhere in the body and spreading to the spine (cancerresearchuk.org). Secondary tumours are much more prevalent than primary tumours. They occur in approximately 70% of cancer patients (Ciftdemir et al. 2016) whereas primary tumours occur in approximately 0.07% of healthy people (Schellinger et al. 2008). The most common types of primary tumours are meningiomas (29%), nerve-sheath tumours (24%) and ependymomas (23%) (Schellinger et al. 2008).  Secondary tumours can metastasise from many different areas of the body; most commonly they may spread from breast, lung and prostate primary tumours (John Hopkins Medicine, 2020).

In a primary care setting, malignancy is extremely rare. ‘Table 1’ highlights the incidence primary diagnoses given that may result in low back pain within NHS primary care settings in the UK in 2018/19. 96,420,114 patients were seen in total (Barnes, 2019).

Condition	Number of primary diagnoses	% of total cases
Low back pain	45,520	0.04%
Malignant neoplasm: Vertebral column	136	0.00%
Malignant neoplasm: Connective and soft tissue of trunk	85	0.00%
Malignant neoplasm: Spinal meninges	1	0.00%
Malignant neoplasm: CNS unspecified	233	0.00%
Malignant neoplasm of other and ill-defined sites: Lower limb	74	0.00%
Secondary malignant neoplasm of other unspecified parts of the nervous system	158	0.00%
Secondary malignant neoplasm of bone and bone marrow	17,629	0.02%

Prognosis

Around 10-20% of patients diagnosed with spinal metastasis live for longer than two years after this diagnosis (Delank et al. 2011). Better prognoses and longer survival rates have been associated with earlier detection of the tumour (Ruckdeschel, 2005). Therefore, it is important to screen patients with low back pain for red flags associated spinal malignancy.

Clinical Indicators

When assessing patients with low back pain, there are a number of ‘red flags’ which may increase suspicion of spinal malignancy. Large scale studies by Henschke et al. (2013), Premkumar et al. (2018) and Tsiang et al. (2019) have identified numerous clinical indicators of malignancy that should be screened for during the assessment of these patients.

These studies accept that no single ‘red flag’ can be used in isolation to give a diagnosis of spinal malignancy. Instead, a combination may increase a clinician’s index of suspicion. The literature stated that patient-reported history of cancer, alongside low back pain, was identified as the most significant sign of spinal malignancy. Interestingly, Premkumar et al. (2018) reported that a past medical history of cancer, combined with unexplained weight loss, produced a specificity of 99.8%. The summary of findings from these studies is detailed in table X below.

Indicator	Sensitivity (%)	Specificity (%)
Age >50	71.7	32.6
Age >70	22.6	79.5
Night pain	54.2-55.4	41.8-49.6
Unexplained weight loss	8.2	95.6
Pain at rest	25	69.8
Urinary retention	4.2	95.8
History of cancer	32-75	78.7-95.6
History of cancer + Unexplained weight loss	2.5	99.8

A Cochrane review carried out by Henschke et al. (2013) examining studies containing over 6000 patients emphasised the need for an affective diagnostic test to assist in the identification of spinal malignancy in patients with low back pain.

References

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