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Chronic low back pain: epidemiology, pathogenesis, and management

Chronic low back pain

Author: Dr. Faisal Hayat, MBBS

Epidemiology of chronic low back pain

Chronic low back pain (CLBP) is defined as pain occurring for more than three months of the period in the lower back region between the posterior lower rib margin and the horizontal gluteal fold. 1 It is the most prevalent type of chronic pain in adults. 2 It is one of the most common health problems worldwide. As per the Global Burden of Disease study, low back pain is included in one of the top ten diseases and injuries that people face daily. 3 It affects around 23% of the population worldwide and recurs within 12 months in 24–80% of the individuals. 4

It is the leading cause of substantial downstream economic losses and reduced quality of life. In the United States, almost $19.6–118.8 billion is an estimated annual medical cost associated with LBP. 5 It has become one of the biggest problems for public health systems in the western world during the second half of the 20th century and now seems to be extending worldwide. 6,7 Its prevalence is increasing substantially with age due to traumas, stress, or intervertebral disc diseases. 8 The lifetime prevalence of low back pain is reported to be as high as 84%, and the best estimate suggests that the prevalence of chronic low back pain is about 23%, with 11–12% of the population being disabled by it.9

Pathophysiology and risk factors of chronic low back pain 

The most important risk factors for chronic low back pain are obesity, female gender, prior history of back pain, older age, restricted mobility of the spine, and smoking. Some others are also included like high levels of psychological distress, pain radiating into a leg, and minimal physical activity. Pain-sensitive structures of the spine include the periosteum of the vertebrae, dura, facet joints, annulus fibrosus of the intervertebral disk, epidural veins and arteries, and the longitudinal ligaments. 21

The mechanism by which intervertebral disk injury causes low back pain is uncertain. Ingrowth of pain nerve fibers into the nucleus pulposus of a diseased disk is responsible for chronic pain. 21 Tumor necrosis factor α (TNFα) has the possible pathophysiological role in low back pain suggested in a study. 10 In another experimental study, it is suggested that nerve growth factors extracted from degenerative nucleus pulposus might have a role in pain transmission. 11 Mechanical factors also have some role in low back pain. In another study, obesity was associated with an increased incidence of low back pain. Research evidence to suggest that physical deconditioning and disuse are directly associated with chronic low back pain, in either a causal or consequential manner, is scarce. 12 A study revealed a slight association between back pain and smoking status. 13 The role of genetic factors is also widely discussed. Twin studies have proven that both low back pain and disc degeneration have a genetic background. 14,15 Almost one-fourth of the genetic effects on pain are attributed to the same genetic factors that affect disc narrowing.

Key Notes:

  • If low back pain occurs for more than three months of period, it is called chronic.
  • Chronic low back pain affects patients from all age groups.
  • It puts a huge burden on economy.
  • It reduces the quality of life.
  • Obesity, female gender, prior history of back pain, restricted spinal mobility, older age, and smoking are the leading risk factors for CLBP.
  • There are multiple factors and causes of the CLBP.
  • Some important causes are lumbar disk disease, degenerative conditions, spondylosis and spondylolisthesis, neoplasms, autonomic, and trauma.
  • In general, the treatment for CLBP is same as the ALBP.

Management

In the United States, low back pain and related spine disorders are the most expensive medical problems to treat. 16,17 Acute low back pain (ALBP) is a self-limited condition and usually resolves without medical treatment in less than a period of one month. On the other hand, CLBP is a persistent form of low back pain that causes substantial limitations in the activity.18 Recently, nonpharmacologic interventions, such as heat, massage, acupuncture, or spinal manipulation, are recommended as first-line treatment options, while initial use of diagnostic imaging, specialty consultation, and prescription of opioid medications in the absence of red flags are not recommended. 19 The red flags are fever, fracture, malignant neoplasms, etc. Current literature suggests that NSAIDs and acetaminophen as well as antidepressants, muscle relaxants, and opioids are effective treatments for CLBP. A randomized controlled trial in 2019, evaluated the benefit of tramadol, buprenorphine, and stronger opioids such as oxycodone. 20

The initial assessment excludes serious causes of spine pathology that require urgent intervention. These serious causes are infection, cancer, or trauma. Educate and reassure the patients that improvement is very likely. 21 In general, avoid bed rest for relief of severe symptoms or kept to a day or two at most.

Sometimes it is helpful to use heating pads or blankets. The anti-inflammatory effects of NSAIDs might provide an advantage over acetaminophen to suppress inflammation but there is no clinical evidence to support the superiority of NSAIDs. 21 NSAIDs increase the risk of renal and GI toxicity in patients with preexisting medical comorbidities. Some patients take NSAIDs and acetaminophen together for a more rapid benefit. Skeletal muscle relaxants, such as methocarbamol or cyclobenzaprine, may be useful. Muscle relaxants cause sedation. If these interfere with sleep, prefer to use it at night time only. The use of opioid analgesics or tramadol as first-line therapy for ALBP does not have good evidence. So, the use of opioids or tramadol is best reserved for patients who cannot tolerate acetaminophen or NSAIDs and for those with severe refractory pain. Side effects of opioids are constipation, nausea, and pruritus. Falls, fractures, driving accidents, and fecal impaction can also be present. In general, the same treatments that are recommended for ALBP can be useful for patients with CLBP.

In general, activity tolerance is the primary goal, while pain relief is secondary. Evidence supports the use of exercise therapy to relieve pain and improve function. Exercise can be one of the mainstays of treatment for CLBP. In one randomized trial, cognitive behavioral therapy reduced disability and pain in patients with CLBP. These behavioral treatments have similar benefits as exercise therapy. Massage therapy is helpful for short-term relief only. Various injections, including epidural glucocorticoid injections, facet joint injections, and trigger point injections, are also useful for treating CLBP. 21

Electrothermal and radiofrequency therapy is also a category to treat CLBP. 21 Intradiscal therapy uses both types of energy to thermocoagulation and destroys nerves in the intervertebral disk, using specially designed catheters or electrodes. The radiofrequency denervation technique has been used for facet joint pain (with the target nerve being the medial branch of the primary dorsal ramus), for back pain thought to arise from the intervertebral disk (ramus communicans), and radicular back pain (dorsal root ganglia).21 It destroys the nerves that are thought to mediate pain. Guidelines suggest that referral for an opinion on spinal fusion should be considered for those who have persistent severe back pain or who have completed an optimal nonsurgical treatment program (including combined physical and psychological treatment). Lumbar disk replacement with prosthetic disks is approved by U.S. Food and Drug Administration (FDA) for uncomplicated patients needing single-level surgery at the L3-S1 levels.21 This treatment remains controversial for CLBP. Intensive multidisciplinary rehabilitation programs are helpful for patients who have not responded to other approaches. It includes daily or frequent physical therapy, exercise, CBT, a workplace evaluation, and other interventions. 21

Conclusion

  • ALBP is a self-limiting condition.
  • Non-pharmacological treatment options are the firstline.
  • First of all, look for the serious causes of spine pathology.
  • Educate and reassure the patient.
  • NSAIDs, acetaminophen, muscle relaxants, antidepressants, and opioids are the pharmacological treatment options for CLBP.
  • If a patient cannot tolerate NSAIDs or acetaminophen than use opioids or tramadol.
  • Exercise can be a mainstay of treatment for CLBP.
  • Behavioral therapy is also helpful.
  • Massage therapy is also useful for short-term relief.
  • Electrothermal and radiofrequency therapy like intradiscal therapy is also useful.
  • Intensive multidisciplinary rehabilitation programs are also helpful if a patient is not responding to other approaches.

References

    1. Dagenais S, Caro J, Haldeman S. A systematic review of low back pain cost of illness studies in the United States and internationally. Spine J. 2008;8(1):8–20. doi: 10.1016/j.spinee.2007.10.005
    2. Oliveira CB, Maher CG, Pinto RZ, et al. Clinical practice guidelines for the management of non-specific low back pain in primary care: an updated overview. Eur Spine J. 2018;27(11):2791-2803.
    3. Patrick N, Emanski E, Knaub MA. Acute and chronic low back pain. Med Clin N Am. 2014;98(4):777– 789. doi: 10.1016/j.mcna.2014.03.005
    4. El-Sayed AM, Hadley C, Tessema F, Tegegn A, Cowan JA Jr, Galea S. Back and neck pain and psychopathology in rural Sub-Saharan Africa: evidence from the Gilgel Gibe Growth and Development Study, Ethiopia. Spine (Phila Pa 1976) 2010; 35: 684–89.
    5. Dieleman JL, Cao J, Chapin A, et al. US health care spending by payer and health condition, 19962016.JAMA. 2020;323(9):863-884.
    6. Auvinen JP, Paananen MV, Tammelin TH, et al. Musculoskeletal pain combinations in adolescents. Spine (Phila Pa 1976) 2009; 34: 1192–97.
    7. Pellise F, Balague F, Rajmil L, et al. Prevalence of low back pain and its effect on health-related quality of life in adolescents. Arch Pediatr Adolesc Med 2009; 163: 65–71.
    8. Pizzo PA, Clark NM, Carter-Pokras O, et al Relieving Pain in America: A Blueprint for Transforming Prevention, Care, Education, and Research. Washington, DC 2011.
    9. Jordan KP, Kadam UT, Hayward R, Porcheret M, Young C, Croft P. Annual consultation prevalence of regional musculoskeletal problems in primary care: an observational study. BMC Musculoskelet Disord 2010; 11: 144.
    10. Roff ey DM, Wai EK, Bishop P, Kwon BK, Dagenais S. Causal assessment of workplace manual handling or assisting patients and low back pain: results of a systematic review. Spine J 2010; 10: 639–51.
    11. Roff ey DM, Wai EK, Bishop P, Kwon BK, Dagenais S. Causal assessment of occupational pushing or pulling and low back pain: results of a systematic review. Spine J 2010; 10: 544–53.
    12. Reimann F, Cox JJ, Belfer I, et al. Pain perception is altered by a nucleotide polymorphism in SCN9A. Proc Natl Acad Sci USA 2010; 107: 5148–53.
    13. Tegeder I, Lotsch J. Current evidence for a modulation of low back pain by human genetic variants. J Cell Mol Med 2009; 13: 1605–19.
    14. Karppinen J, Solovieva S, Luoma K, Raininko R, Leino-Arjas P, Riihimaki H. Modic changes and interleukin 1 gene locus polymorphisms in an occupational cohort of middle-aged men. Eur Spine J 2009; 18: 1963–70.
    15. Dai F, Belfer I, Schwartz CE, et al. Association of catechol-O-methyltransferase genetic variants with outcome in patients undergoing surgical treatment for lumbar degenerative disc disease. Spine J 2010; 10: 949–57
    16. Hoy D, Brooks P, Blyth F, Buchbinder R. The epidemiology of low back pain. Best Pract Res Clin Rheumatol. 2010;24(6):769–81.
    17. Will J, Bury D, Miller JA. Mechanical low back pain: prevention. Am Fam Physician. 2018;98(7):421– 8
    18. Kim LH, Vail D, Azad TD, et al. Expenditures and health care utilization among adults with newly diagnosed low back and lower extremity pain.JAMA Netw Open. 2019;2(5): e193676. D
    19. Chaparro LE, Furlan AD, Deshpande A, MailisGagnon A, Atlas S, Turk DC. Opioids compared to placebo or other treatments for chronic low-back pain. Cochrane Database Syst Rev. 2013.
    20. Airaksinen O, Brox JI, Cedraschi C, et al. Chapter 4. European guidelines for the management of chronic nonspecific low back pain. Eur Spine J 2006; 15 (suppl 2): S192–300.
    21. Jameson J.L., Fauci A.S., Kasper D.L., Hauser S.L., Longo D.L., and Loscalzo J., Harrison’s Principles of Internal Medicine. 20th ed. McGraw-Hill Education.

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