Table 1.

Diagnosis.

Author	Year	Country	Red Flags	Psychosocial Risk Factor	History and Physical Examination	Imaging
van Wambeke [18]	2017	Belgium	Assess for signs of serious underlying conditions including cancer, infection, trauma, inflammatory or severe neurological impairments (e.g., cauda equina syndrome) Search for differential diagnoses particularly for new or changed symptoms	Consider using screening tools for risk stratification (e.g., STarT Back or Örebro) for new episodes from 48 h after the pain onset. Risk stratification is aimed at informing shared decision making about stratified management	There is insufficient evidence to recommend for or against specific clinical tests, because no test considered in isolation has adequate sensitivity and specificity for determining the cause of pain The objective of history taking and physical examination is to assess for signs of serious underlying condition	Imaging should not be routinely offered in the absence of red flags Consider prescribing imaging if expected results may lead to change management Explain to patients with low back pain that imaging may not be necessary
TOP [13]	2015	Canada	Assess for signs of serious underlying conditions requiring specific evaluation and treatment Search for surgical emergency (e.g., cauda equina syndrome)	Assess for psychosocial risk factors (i.e., yellow flags including include fear, financial problems, anger, depression, job dissatisfaction, family problems or stress) Conduct a review of these factors if there is no improvement There is insufficient evidence to recommend for or against using screening tools for risk stratification	There is insufficient evidence to recommend for or against using the Clinically Organized Relevant Exam (CORE)	Lumbar spine X-rays are poor indicators of serious underlying conditions. In the absence of red flags, spinal and lumbar spine X-rays are not recommended Specific and appropriate diagnostic imaging should be selected on the basis of the condition being sought Lumbar spine X-rays may be considered prior to other diagnostic imaging to assess stability and stenosis (e.g., MRI): views should be limited to standing antero-posterior and lateral views. MRI scanning has limited value in the absence of red flags, radiculopathy or neurogenic claudication CT scans may be considered when vertebral fractures are suspected, or MRI contraindicated
Chenot [14]	2017	Germany	Assess for signs requiring specific imaging or laboratory tests and/or referral to a specialist	Assess for psychosocial and workplace risk factors from the beginning Consider using screening tools for psychosocial (i.e., yellow flags) and workplace risk factors from 4 weeks after the pain onset if pain persists despite adequate treatment (i.e., provided in accordance with guidelines)	The objective of history taking and physical examination is to assess for signs of a dangerous course of the disease or serious underlying condition When such signs are absent, no further diagnostic steps should be undertaken, because they will exceptionally result in a specific diagnosis, and may promote chronic pain	Current evidence does not support routine imaging Indication for diagnostic imaging should be reassessed from 4 to 6 weeks after the pain onset if pain or activity limitations persist despite adequate treatment (i.e., provided in accordance with guidelines) Indication for diagnostic imaging may be reassessed earlier, from 2 to 4 weeks after the pain onset, if a currently employed patient has been unable to work for a long period of time, or if a diagnostic evaluation is required before multimodal treatment Imaging that lacks any potential therapeutic relevance should be avoided
HAS [2]	2019	France	Assess for signs of underlying conditions requiring specific and/or urgent care in case of recent lumbar pain or worsening of symptoms or new symptoms (i.e., acute flare-up of low back pain or change in symptoms)	Assess early for psychosocial risk factors (i.e., yellow flags). Fears and beliefs, psychological and social contexts must be identified early Consider using screening tools for risk stratification (e.g., STarT Back or Örebro) to assess the risk for chronic pain. Other specific questionnaires assessing the level of fears and avoidances (e.g., FABQ) or symptoms of anxiety and depression (e.g., HADS) can also be used Assess for risk factors of prolonged inability to work and/or to return to work (i.e., blue flags and black flags) in the event of repeated or prolonged (>4 weeks) sick leave. Consider requesting the expertise of an occupational physician in this case	No data	It is recommended to explain to the patient why imaging is not necessary in the first place, and if there is absence of systematic correlation between the symptoms and the radiological signs In the absence of a red flag, spinal imaging (i.e., MRI or a CT scan if MRI is contra-indicated) should be considered if pain persists beyond 3 months, or if an invasive procedure (epidural infiltration or spinal surgery) is planned In the absence of a red flag, there is no indication to perform isolated X-rays, except to asses for instability or spinal deformity There is no indication to repeat imaging in the absence of changes in symptoms
NICE [12]	2016	UK	Assess for alternative conditions, particularly for new or changed symptoms Search for specific causes of low back pain including cancer, infection, trauma or inflammatory disease	Consider using screening tools for risk stratification (e.g., STarT Back), at first point of contact with a healthcare professional, for each new episode of low back pain, in order to inform shared decision making about stratified management	No data	Imaging should not be routinely offered Explain to patients that they may not need imaging Consider imaging in specialist settings of care, only if the result is likely to change management
Qaseem [17]	2017	USA	No data	No data	No data	No data
NASS [16]	2020	North America	No data	Assess for psychosocial and workplace risk factors for chronic pain Consider previous episodes of low back pain as a prognostic factor for chronic pain Consider pain severity and functional impairment to stratify the risk for chronic pain Consider psychosocial factors as prognostic factors for return to work following an episode of acute low back pain	Consider a nonstructural cause of low back pain in patients with diffuse low back pain and tenderness Using fear avoidance behavior to determine the likelihood of a structural cause of low back pain There is insufficient evidence to recommend for or against using diffuse low back tenderness to predict the presence of disc degeneration	There is insufficient evidence to recommend for or against an association between low back pain and spondylosis There is insufficient evidence to recommend for or against imaging in the absence of a red flag to recommend for or against imaging findings correlating with low back pain There is insufficient evidence to determine whether imaging findings contribute to decision making to guide treatment
ACOEM [23]	2020	USA	Assess for red flags through medical history and physical examination	Assess for psychosocial risk factors at follow-up visits	Physical examination includes straight leg raising test and neurological examination.	Assess for nerve root compression by MRI or CT-scan in patients with symptoms that are not improving over 4 to 6 weeks with signs of nerve root dysfunction
VA/DOD [4]	2017	USA	Assess for neurologic deficits through medical history and physical examination (e.g., radiculopathy, neurogenic claudication) Assess for signs of serious underlying conditions including malignancy, fracture, infection	Perform mental health screening to inform selection of treatment	History taking and physical examination are critical to identify treatable causes of low back pain	Diagnostic imaging may be considered in patients with serious or progressive neurologic deficits, or when a red flag is present There is insufficient evidence to recommend for or against imaging in patients with pain for longer than 1 month who have not improved or responded to initial treatments