Challenges Associated with Low Back Pain

There are many challenges involved in the management of common LBP that have made it difficult for all stakeholders, including patients, clinicians, third-party payers, and policy makers, to deal with this universal problem. These challenges relate to its epidemiology, etiology, clinical characteristics, prognosis, temporality, risk factors, diagnostic testing, subgroups, diagnostic classifications, health care professionals, direct health care costs, and indirect non–health care costs. Each is briefly discussed below.

Epidemiology

The magnitude of LBP as a health concern can be illustrated by reviewing its epidemiologic characteristics and perhaps most importantly its prevalence. Studies of adults from the general population in a number of developed countries have reported that the prevalence of LBP is quite high, and increases according to the time span considered. The point prevalence of bothersome LBP has been estimated at 25%, whereas the 1-year prevalence has been estimated at 50% and the lifetime prevalence has been estimated at 85%.¹^–³ These statistics mainly hold true regardless of age, sex, or country and vary only slightly between occupations. The odds of someone never experiencing LBP in their life are therefore stacked 6:1 against them. There is some evidence to suggest that everyone will at some point in their life experience LBP and that surveys suggesting otherwise are including people who are young and have not yet experienced LBP or have experienced LBP in the past and have simply forgotten this fact.⁴ The sheer number of people with LBP must always be considered when examining how this condition should be optimally managed, because solutions should ideally be available to the masses rather than the few.

Clinical Characteristics

Many episodes of common LBP are trivial, often beginning with minor aches and pains in the lower spine that can occur without reason or shortly after an unusually heavy bout of physical activity, or without any obvious reason at all, and resolving within a few days without receiving any particular intervention.^5,⁶ Other instances of LBP, however, can be much more severe, frightening, and debilitating. Symptoms may include muscle spasms seemingly precipitated by any movement, as well as searing, burning pain that radiates into the thigh, leg, or foot, or even numbness, tingling, and weakness throughout the lower extremities. The sudden appearance of one or more of these symptoms can be frightening and can severely impact a person’s ability to carry out activities of daily living, whereas their gradual worsening can impact one’s general mood and outlook on life.

Prognosis

It is common wisdom that a substantial majority of those who suddenly develop LBP will quickly improve on their own regardless of the care received. This belief is founded on studies conducted a few decades ago in which those who recently developed LBP were followed prospectively and asked about the severity of their symptoms after various time intervals.⁷ In these studies, patients often reported that their symptoms had improved markedly within several weeks.⁷ By carrying forward this observed reduction in severity, it was natural for researchers to conclude that symptoms should disappear entirely within, at most, a few months.

However, this assumption has been questioned by other epidemiologists who found it difficult to reconcile this theoretically favorable prognosis with the substantial number of patients who still reported symptoms many years after their original episode of LBP. When researchers reexamined those original studies, another hypothesis emerged for their results. Although symptoms often do recede within a few months, the follow-up periods were often too short to capture the longer-term recurrences and exacerbations of symptoms that were common with LBP. By truncating the length of follow-up, these studies failed to observe the true pattern of waxing and waning symptoms. Currently, LBP can be considered a recurrent disorder that can occur at any time in a person’s life and fluctuates between a status of no pain or mild pain, and pain that reaches a point where it interferes with activities of normal living or becomes debilitating.

Temporality

The current consensus on the prognosis of LBP has become more nuanced. The prognosis for LBP is generally favorable for those with recent symptoms, but somewhat grim for those with longstanding symptoms. It became important to adopt a universal terminology to define the temporality of LBP to appreciate this distinction. People whose symptoms lasted less than 6 weeks since onset were generally categorized as having “acute LBP,” progressing to “subacute LBP” if symptoms lasted 6 to 12 weeks, and “chronic LBP (CLBP)” if symptoms persisted beyond 12 weeks.⁸ Further gradations have been suggested for those with longstanding symptoms that disappeared for a time and reappeared, which can be considered “recurrent” or “episodic” LBP.⁹

Although acknowledging that the duration of symptoms affects the prognosis of LBP was important, the demarcation of patients into those with acute, subacute, or chronic LBP has never been as clear as many had wished. Both the severity and duration of symptoms vary from episode to episode, and episodes often become intertwined, with no clear beginning and end. This makes it difficult to define patients using such simple temporal labels. The perception that acute LBP goes away rapidly without returning has been proven false, but so has the seemingly gloomy prognosis attributed to someone who has crossed the 3-month threshold and been labeled as “chronic,” a term often perceived as incurable rather than longstanding by patients. Another phenomenon that has been noted is that as the length of follow-up in clinical studies increased, the results of all treatments studied generally grew less impressive as outcomes gradually regressed to the mean.

Etiology

One of the greatest mysteries surrounding common LBP is its etiology. Epidemiologic, anatomic, biomechanical, and pathologic studies into the etiology of common LBP have yet to create a clear link between precise risk factors or a specific tissue injury and particular symptoms. In fact, such studies have identified abundant theories and hypotheses about the origins of LBP, few of which have withstood scientific scrutiny over time.^8,¹⁰ Exploration of a condition’s etiology often begins by identifying risk factors thought to contribute to its onset in the hope that it will provide information about the precise nature of any pathognomonic injuries. The number of studies conducted in recent decades that have attempted to evaluate potential risk factors for common LBP is impressive, but their findings are often difficult to interpret because they are diverse, nonspecific, and frequently disputed among clinicians and researchers.^11,¹²

Sociodemographic factors such as age, gender, education, and marital status have all been identified as risk factors for developing or prolonging episodes of common LBP.^9,¹³ Similarly, occupational factors such as work satisfaction, autonomy, supervisor empathy, monotonous or repetitive tasks, and prolonged exposure to heavy physical activities including lifting, carrying, and manual handling, have also been identified as risk factors for common LBP.^2,¹⁴^–¹⁶ General health factors including tobacco use, body weight, physical activity levels, and the presence of systemic, physical, or psychological comorbidities have also been implicated in LBP.^6,^9,¹⁷ Socioeconomic factors including income level, involvement in worker’s compensation, personal injury, or other litigation, and availability of supplemental disability insurance are also thought to impact the severity or duration of common LBP.^9,¹⁶ Genetic factors have also been identified that may increase the risk for development of lumbar degenerative disc disease, which may lead to LBP.¹⁸

Diagnostic Testing

Even though few of the suspected risk factors for LBP are able to elucidate a clear mechanism of injury and identify a specific anatomic structure that can be targeted with an intervention, diagnostic tests are often ordered to find tissue pathology. These tests include plain film x-ray studies, magnetic resonance imaging (MRI), and computed tomography (CT). Although diagnostic imaging occasionally identifies serious pathology that may be responsible for symptoms of LBP and requires urgent and targeted intervention, this is the exception rather than the rule. Too often, diagnostic imaging reports list findings that should be considered normal signs of aging (e.g., disc degeneration) or normal anatomic variants (e.g., minor positional misalignments or disc bulging).^2,^19,²⁰ Further clouding the interpretation of diagnostic imaging reports is that findings may not correlate with the clinical presentation, making their significance dubious at best (e.g., left-sided disc protrusion at L4 with symptoms of right-sided thigh numbness). In fact, there are a number of studies that have shown that adults who are not reporting LBP having significant abnormalities on x-ray studies, CT scans, and MRI.²¹^–²⁶ The results of diagnostic testing for common LBP must therefore be interpreted with caution.

Subgroups

Currently, LBP is viewed as a symptom rather than a medical diagnosis because it can be caused by a variety of conditions, including some that may originate outside the lumbar spine. For example, one of the first symptoms of kidney stones may be LBP, but applying a diagnosis of LBP to such a patient and prescribing analgesics would be ignoring the underlying illness. Conversely, a prolonged search for a specific diagnosis for a patient in otherwise good health who reports moderate LBP will likely prove fruitless because nociceptive input can be triggered by dozens of anatomic structures and result in similar symptoms. Clinicians faced with a patient who reports LBP must therefore balance these two extremes. First, clinicians must be vigilant to avoid missing rare but potentially serious pathology that may manifest itself as LBP. Second, they must refrain from ordering unnecessary diagnostic tests that will not change their recommended management approach and could confound what is an otherwise simple clinical scenario.

Diagnostic Classifications

Numerous diagnostic classifications have been proposed for LBP in an attempt to simplify the dozens of potentially underlying pathologies that may account for a group of related symptoms. One of the simplest has been extrapolated from an increasingly popular method of defining neck pain. Under this terminology, patients presenting with LBP can be divided into four categories or diagnostic groups, each of which requires a different management approach. Group 1 is common, nonspecific, and nondebilitating LBP that does not impact activities of daily living. Group 2 includes people with LBP that has become disabling and is interfering with activities of daily living; people in this group commonly seek care. Group 3 includes people who have demonstrable neurologic deficits, including motor, sensory, or reflex changes that are suggestive of an anatomic lesion compressing a neurologic structure. Group 4 includes people with serious and often progressive spinal pathology, which can be differentiated into two subgroups. The first is likely to require surgery (e.g., spinal tumor, spinal abscess, spinal fracture, cauda equina syndrome). The second is likely to respond to medical intervention, although surgery may become necessary if the problem is not resolved by medical intervention (e.g., infection, osteoporosis, ankylosing spondylitis, rheumatoid arthritis).

Several terms are often used to describe LBP that falls into groups 1 and 2, including nonspecific LBP (i.e., no specific cause has been identified for these symptoms), mechanical LBP (i.e., symptoms appear to be exacerbated when a mechanical load is applied to the lumbar spine), common LBP, musculoskeletal LBP, or simple LBP. These terms are often used interchangeably and generally indicate that a working diagnosis of common LBP has been established after reasonable efforts have been made by a clinician to rule out a specific cause of LBP. It has been estimated that less than 1% of LBP is associated with potentially serious spinal pathology requiring surgery, 1% with specific spinal pathology requiring medical intervention, and 5% to 10% with substantial neurologic involvement.^27,²⁸

Given our current understanding, it does not appear to be possible to establish a specific diagnosis for more than 90% of patients with LBP.^19,^27,²⁸ The vast majority of patients can simply be said to have common LBP that may or may not be impacting their activities of daily living. This notion of common LBP can be difficult for both patients and clinicians to accept, in that it seems to contradict the basic sequence of events used in many other areas of modern medicine: elicit a history, develop a differential diagnosis, examine the patient, refine the differential diagnosis, order diagnostic tests, further refine the differential diagnosis, apply an intervention targeted at the diagnosis, and implement a cure. This can make it difficult for some patients and clinicians trained in the classical method of treating disease to accept the uncertainty of a diagnosis of nonspecific LBP and address the problem according to the current scientific evidence.

Health Care Professionals

Further compounding the clinical challenge presented by common LBP is the number of health care professionals involved in its diagnosis and management, each of whom may approach a patient with LBP according to their particular training and experience with this condition. Unlike many other medical conditions that are clearly identified with a particular health care discipline (e.g., cancer and oncology, tooth disease and dentistry), a variety of clinicians must contend with common LBP, whether by choice or by chance. Care for common LBP is also sought in many different settings across the health care spectrum, including primary, secondary, and even tertiary medical care, as well as allied health, and complementary and alternative medicine practitioners. Health care professionals who are routinely consulted for LBP are listed in Box 1-1.

In the absence of clear scientific evidence about the etiology and ideal management of LBP, many health care disciplines have developed their own views on how to deal with this condition. Naturally, these views are shaped by the extent and nature of their academic and clinical experience, as well as their scope of practice, state licensing laws, third-party reimbursement policies, and patient demand for specific services. In aggregate, these factors have resulted in health care professionals from different disciplines using treatment strategies as divergent as acupuncture, traction therapy, anticonvulsant medications, cognitive behavioral therapy, facet neurotomy, arthrodesis, and spinal manipulation under anesthesia, to name only a few interventions. For particularly severe or recalcitrant cases of LBP, multiple interventions may be used simultaneously (e.g., opioid analgesics with epidural steroid injections and massage).

Direct Health Care Costs

Given the high number of patients who report common LBP and seek care from a variety of health care professionals who then order multiple diagnostic tests before recommending a panoply of interventions, it should come as no surprise that the direct health care costs associated with LBP are substantial. In the United States, yearly direct health care costs associated with back and neck problems—most commonly LBP—were estimated to have doubled over 7 years, from $52.1 billion in 1997 to $102 billion in 2004, before settling to $85.9 billion in 2005.²⁹ This increase in health care costs cannot solely be attributed to the number of people afflicted with LBP because the prevalence on which those estimates are based was 13.7% in 1997 and 15.2% in 2005, an annualized increase of only 1.5%, whereas costs rose at an annual rate of 7.5%. Similarly, high direct health care costs have been reported for LBP in other developed countries, including the United Kingdom, the Netherlands, Sweden, Australia, Belgium, and Japan.³⁰ LBP often ranks among the 10 most expensive medical conditions, with costs similar to those associated with cancer, cardiovascular disease, or diabetes.³⁰

The problem is that disability associated with LBP appears to be increasing even though more money is being spent to relieve its symptoms. As noted by Martin and colleagues,²⁹ there was a substantial increase in the expenditure for all categories of treatment for LBP. At the same time, the estimates of self-reported physical limitations of those with LBP increased from 20.7% in 1997 to 24.7% in 2005. This study also noted that there was a marked increase in the overall health care expenditure in patients who experienced LBP compared with those who were not experiencing LBP. In 2005, the mean age- and sex-adjusted medical expenditure among respondents with spinal problems was $6096, compared with $3516 among respondents without spinal problems. Not all of this increase can be attributed to treatment directed at their spinal problems, but it may be a marker for increased overall health seeking behavior among those with LBP.