The Lancet Journal has recently published a series of papers on low back pain (LBP). The global burden of LBP is increasing, however there is a need to identify cost-effective and context-specific strategies for managing low back pain to mitigate the consequences of the current and projected future burden.

Low back pain is increasingly understood as a long lasting condition with a variable course rather than episodes of unrelated occurrences. It is now the number one cause of disability globally.

Key messages

• The largest increases in disability caused by low back pain in the past few decades have occurred in low-income and middle-income countries, including in Asia, Africa, and the Middle East, where health and social systems are poorly equipped to deal with this growing burden in addition to other priorities such as infectious diseases.

• Lifestyle factors, such as smoking, obesity, and low levels of physical activity, that relate to poorer general health, are also associated with occurrence of low back pain episodes.

• Initial high pain intensity, psychological distress, and accompanying pain at multiple body sites increases the risk of persistent disabling low back pain.

• People with low back pain often have concurrent pain in other body sites, and more general physical and mental health problems, when compared with people not reporting low back pain.

• Central pain-modulating mechanisms and pain cognition have important roles in the development of persistent disabling low back pain.

• Patients with chronic low back pain show structural brain differences in specific cortical and subcortical areas, and altered functional connectivity in pain-related areas following painful stimulation.

• Most episodes of low back pain are short-lasting with little or no consequence, but recurrent episodes are common and low back pain is increasingly understood as a long-lasting condition with a variable course rather than episodes of unrelated occurrences.

What is low back pain?

Low back pain is a symptom not a disease. For nearly all people presenting with low back pain, the specific nociceptive source cannot be identified and those affected are then classified as having so-called non-specific low back pain.

Potential nociceptive contributors to low back pain that have undergone investigation

Intervertebral disc

No investigation has accurately identified a disc problem as contributing to an individual’s pain; there is no widely accepted reference standard for discogenic pain.

Disc herniations are, a frequent finding on imaging in the asymptomatic population, and they often resolve or disappear over time independent of resolution of pain.

Facet joint

Clinical identification of individuals whose facet joints are contributing to their pain is not possible.

Vertebral endplates (Modic changes)

Modic changes are vertebral endplate abnormalities seen on MRI with specific subchondral and vertebral bone marrow features that can be classified according to different signal intensities into type 1, type 2, and type 3; identification of individuals in whom Modic changes are contributing to their pain is not possible.

Neurological symptoms associated with low back pain

Radicular pain and radiculopathy

Radicular pain occurs when there is nerve-root involvement. The diagnosis of radicular pain relies on clinical findings, including a history of dermatomal leg pain, leg pain worse than back pain, worsening of leg pain during coughing, sneezing or straining, and straight leg raise test.

People with low back pain and radicular pain or radiculopathy are reported to be more severely affected and have poorer outcomes compared with those with low back pain only.

Lumbar spinal stenosis

Clinically characterised by pain or other discomfort with walking or extended standing that radiates into one or both lower limbs and is typically relieved by rest or lumbar flexion. Symptoms of lumbar spinal stenosis are thought to result from venous congestion or ischaemia of the nerve roots in the cauda equina due to compression.

Specific pathological causes of low back pain

Vertebral fracture

Symptomatic minimal trauma vertebral fractures have been shown in some studies to have a major health impact with a mean of 158 days of restricted activity and a third of those affected still have significant back pain after 2 years. In some studies, minimal trauma vertebral fractures are also associated with a two-to-eight times increased risk of mortality.

Axial spondyloarthritis

Axial spondyloarthritis is a chronic inflammatory disease that mainly affects the axial skeleton in young people (peak of onset 20–40 years), also termed ankylosing spondylitis

The typical presentation of axial spondyloarthritis includes morning stiffness, mostly in the lower back, with improvement seen with exercise but not with rest.

Malignancy

Back pain is a common symptom in people with metastatic cancer. Nevertheless, malignancy is an uncommon cause of low back pain. Past history of malignancy is the most useful indicator for identifying such disease in people presenting with low back pain.

Infections

Spinal infections include spondylodiscitis, vertebral osteomyelitis, epidural abscess, and rarely facet joint infection.

In low-income countries, tuberculosis affects a broader span of ages (mean age 27–76 years), and could represent up to a third of spinal infections.

Cauda equina syndrome

Cauda equine compression, which mainly arises from disc herniation, can have catastrophic consequences.

Early diagnosis and surgical treatment are probably helpful; therefore, there needs to be a low threshold for further assessment when there has been a new onset of perianal sensory change or bladder symptoms, or bilateral severe radicular pain with low back pain of any duration. The cardinal clinical features are urinary retention and overflow incontinence (sensitivity 90%, specificity 95%).

MRI and low back pain Evidence is insufficient to know whether MRI findings can be of use to predict the future onset, or the course, of low back pain. Importantly, no evidence exists that imaging improves patient outcomes and guidelines consistently recommend against the routine use of imaging for people with low back pain.

Risk factors and triggers for episodes of low back pain

• People who have had previous episodes of low back pain.

• Chronic conditions, including asthma, headache, and diabetes.

• Pain-free individuals with depression and anxiety.

• Workers with awkward postures, heavy manual tasks or feeling tired.

• People with low income and short education disproportionally.

Reference:

What low back pain is and why we need to pay attention

Jan Hartvigsen*, Mark J Hancock*, Alice Kongsted, Quinette Louw, Manuela L Ferreira, Stéphane Genevay, Damian Hoy, Jaro Karppinen, Glenn Pransky, Joachim Sieper, Rob J Smeets, Martin Underwood, on behalf of the Lancet Low Back Pain Series Working Group