Nature and Burden of Low Back Pain

Low back pain is one of the most frequently encountered conditions in clinical practice. Up to 84 percent of adults have low back pain at some time in their lives, and over one quarter of U.S. adults report recent (in the last 3 months) low back pain.^{1, 2} Low back pain can have major adverse impacts on quality of life and function. Low back pain is also costly—in 1998, total US health care expenditures for low back pain were estimated at $90 billion.³ Since that time, costs of low back pain care have risen at a rate higher than observed for overall health expenditures.⁴ In addition to high direct costs, low back pain is one of the most common reasons for missed work or reduced productivity while at work, resulting in high indirect costs.⁵

The prognosis for acute low back pain (generally defined as an episode lasting less than 4 weeks) is generally favorable. Most patients experience a rapid improvement in (and often a complete resolution of) pain and disability and are able to return to work.⁶ In those with persistent symptoms, continued improvement is often seen in the subacute phase between 4 to 12 weeks, though at a slower rate than observed at first. In a minority of patients, low back pain lasts longer than 12 weeks, at which point it is considered chronic; levels of pain and disability often remain relatively constant thereafter.⁷ Recently, a National Institutes of Health Research Task Force defined chronic low back pain as a back pain problem that has persisted at least 3 months and has resulted in pain on at least half the days in the past 6 months.⁸ Patients with chronic back pain account for the bulk of the burdens and costs of low back pain.^{9, 10} Predictors of chronicity are primarily related to psychosocial factors, such as presence of psychological comorbidities, maladaptive coping strategies (such as fear avoidance [avoiding activities because of fears that they will further damage the back] or catastrophizing [anticipating the worst possible outcomes from low back pain]), presence of nonorganic signs (symptoms without a distinct anatomical or physiological basis),¹¹ high baseline functional impairment, low general health status, and others.⁷ Back pain is frequently associated with presence of depression and anxiety.

Attributing symptoms of low back pain to a specific disease or spinal pathology is a challenge.¹² Spinal imaging abnormalities such as degenerative disc disease, facet joint arthropathy, and bulging or herniated intervertebral discs are extremely common in patients with or without low back pain, particularly in older adults, and such findings are poor predictors for the presence or severity of low back pain.¹³ Radiculopathy from nerve root impingement (often due to a herniated intervertebral disc) or spinal stenosis (narrowing of the spinal canal) are each present in about 4 to 5 percent of patients with low back pain and can cause neurological symptoms such as lower extremity pain, paresthesias, and weakness; the natural history and response to treatment for these conditions may differ from back pain without neurologic involvement.¹⁴

Interventions for Low Back Pain

Multiple treatment options for acute and chronic low back pain are available. Broadly, these can be classified as pharmacological treatments,¹⁵ noninvasive nonpharmacological treatments,¹⁶ injection therapies,¹⁷ and surgical treatments.¹⁸ This report focuses on the comparative benefits and harms of pharmacological and noninvasive nonpharmacological treatments; each of these categories encompasses a number of different therapies. Pharmacological treatments include nonsteroidal anti-inflammatory drugs (NSAIDs), acetaminophen, opioids, muscle relaxants, antiseizure medications, antidepressants, and corticosteroids; nonpharmacological treatments include exercise and related interventions (e.g., yoga), complementary and alternative therapies (e.g., spinal manipulation, acupuncture, and massage), psychological therapies (e.g., cognitive-behavioral therapy, relaxation techniques, and operant therapy), physical modalities (e.g., traction, ultrasound, transcutaneous electrical nerve stimulation [TENS], low level laser therapy, interferential therapy, superficial heat or cold, back supports, and magnets), and multidisciplinary rehabilitation.

Rationale for Evidence Review

The burden of low back pain, the numerous noninvasive treatment options to be considered by clinicians and patients, and the availability of new evidence and interventions (e.g., duloxetine) warrant a comprehensive comparative effectiveness review of this topic. An existing guideline¹⁴ and associated systematic reviews^{15, 16} from the American College of Physicians and the American Pain Society were published in 2007, emphasizing the role of pharmacological therapies and noninvasive nonpharmacological therapies for low back pain in most situations. A systematic evidence review that includes recently published research, explores potential variability in response to treatment depending on patient characteristics, considers multiple outcomes related to pain and function, and separately considers benefits and harms of interventions for acute or chronic nonradicular low back pain, as well as conditions such as radiculopathy and spinal stenosis, may provide a better understanding of the comparative effectiveness of treatment options for acute and chronic low back pain and could be used to update existing clinical recommendations. To aid in the efficiency of the review process, this review will be conducted as an update of prior systematic reviews on pharmacological and nonpharmacological noninvasive treatments used to develop the 2007 APS/ACP clinical practice guideline and conducted by the same review team.^{15, 16}

PICOTS

Analytic Framework

The analytic framework (Figure 1) illustrates the population, interventions, outcomes, and adverse effects that will guide the literature search and synthesis.

Figure 1

Analytic framework. * Patient characteristics include clinical, demographic, and psychosocial risk factors associated with low back pain outcomes. † Intermediate outcomes are typically not measured (e.g., inflammation).