The State of Low Back Pain
Written by Editor   
Tuesday, July 10, 2018 07:05 AM

Low back pain is now the number one cause of disability globally. The burden from low back pain is increasing and is straining health-care and social systems that are already over-burdened. Costs associated with health care and work disability attributed to low back pain are enormous. Although there are several global initiatives to address the global burden of low back pain as a public health problem, 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 a very common symptom. Globally, years lived with disability caused by low back pain increased by 54% between 1990 and 2015, mainly because of population increase and ageing, with the biggest increase seen in low-income and middle-income countries. It is now the leading cause of disability worldwide.

Only a small proportion of people have a well understood pathological cause - eg, a vertebral fracture, malignancy, or infection. People with physically demanding jobs, physical and mental comorbidities, smokers, and obese individuals are at greatest risk of reporting low back pain. Disabling low back pain is over-represented among people with low socioeconomic status.  In a small proportion of people, low back pain becomes persistent and disabling.

Initial high pain intensity, psychological distress, and accompanying pain at multiple body sites increases the risk of persistent disabling low back pain. Increasing evidence shows that central pain-modulating mechanisms and pain cognitions have important roles in the development of persistent disabling low back pain.

Disability and costs attributed to low back pain are projected to increase in coming decades. Intensified research efforts and global initiatives are clearly needed to address the burden of low back pain as a public health problem.

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.

Low back pain is a complex condition with multiple contributors to both the pain and associated disability, including psychological factors, social factors, biophysical factors, comorbidities, and pain-processing mechanisms.

Low back pain is a symptom not a disease, and can result from several different known or unknown abnormalities or diseases.  It is defined by the location of pain, typically between the lower rib margins and the buttock creases. It is commonly accompanied by pain in one or both legs and some people with low back pain have associated neurological symptoms in the lower limbs.

There are some serious causes of persistent low back pain (malignancy, vertebral fracture, infection, or inflammatory disorders such as axial spondyloarthritis) that require identification and specific management targeting the cause, but these account for a very small proportion of cases. 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.

Potential pain contributors to low back pain that have undergone investigation include the intervertebral disc, the facet joint, and the vertebral endplates.  

Radicular pain occurs when there is nerve-root involvement; commonly termed sciatica in this region. The term sciatica is used inconsistently by clinicians and patients for different types of leg or back pain and should be avoided. 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. Radiculopathy is characterised by the presence of weakness, loss of sensation, or loss of reflexes associated with a particular nerve root, or a combination of these, and can coexist with radicular pain. 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. Disc herniation in conjunction with local inflammation is the most common cause of radicular pain and radiculopathy. Disc herniations are, however, a frequent finding on imaging in the asymptomatic population, and they often resolve or disappear over time independent of resolution of pain.

Lumbar spinal stenosis is 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. It is usually caused by narrowing of the spinal canal or foramina due to a combination of degenerative changes such as facet osteoarthritis, ligamentum flavum hypertrophy, and bulging discs.

Potential causes of low back pain that might require specific treatment include vertebral fractures, inflammatory disorders (eg, axial spondyloarthritis), malignancy, infections, and intra-abdominal causes. Clinicians do, however, need to consider if the overall clinical picture might indicate a serious cause for the pain, remembering that the picture can develop over time. The US guideline for imaging advises deferral of imaging pending a trial of therapy when there are weak risk factors for cancer or axial spondyloarthritis.

Low back pain is uncommon in the first decade of life, but prevalence increases steeply during the teenage years; around 40% of 9–18-year olds in high-income, medium-income, and low-income countries report having had low back pain. Most adults will have low back pain at some point. The median 1-year period prevalence globally in the adult population is around 37%, it peaks in mid-life, and is more common in women than in men. Low back pain that is accompanied by activity limitation increases with age.

Low back pain is the number one cause of disability globally.  Most people with low back pain have low levels of disability, but the additive effect of those, combined with high disability in a substantial minority, result in the very high societal burden.  Disability from low back pain is highest in working age groups worldwide. Furthermore, occupational musculoskeletal health policies, such as regulations for heavy physical work and lifting, are often absent or poorly monitored.  Thus, disability associated with low back pain might contribute to the cycle of poverty in poorer regions of the world.

Costs associated with low back pain are generally reported as direct medical (health-care) costs, and indirect (work absenteeism or productivity loss) costs. The economic impact related to low back pain is comparable to other prevalent, high-cost conditions, such as cardiovascular disease, cancer, mental health, and autoimmune diseases. Replacement wages account for 80–90% of total costs, and consistently a small percentage of cases account for these.

Low back pain is increasingly understood as a long-lasting condition with a variable course rather than episodes of unrelated occurrences. Around half the people seen with low back pain in primary care have a trajectory of continuing or fluctuating pain of low-to-moderate intensity, some recover, and some have persistent severe low back pain. The best evidence suggests around 33% of people will have a recurrence within 1 year of recovering from a previous episode.

In recent decades, the biopsychosocial model has been applied as a framework for understanding the complexity of low back pain disability in preference to a purely biomedical approach. Many factors including biophysical, psychological, social and genetic factors, and comorbidities can contribute to disabling low back pain. However, no firm boundaries exist among these factors and they all interact with each other.