Chronic Pain Management: An Evidence-Based Approach

Basics

  • Chronic pain persists beyond the time anticipated for normal tissue healing (usually >3 months).
  • Over time, neuroplastic changes in the CNS transform pain into a chronic experience with emotional, psychological, and cognitive dimensions.
  • An epidemic of undertreated pain coexists with an epidemic of prescription drug abuse in the United States.
  • People of color, especially African Americans, are often undertreated.
  • Opioid medications should be prescribed using an evidence/systems-based approach and used only when indicated for chronic, nonmalignant pain.

Epidemiology

Incidence

  • Chronic pain has been reported by as many as 20–40% of patients in primary care.
  • The annual economic cost of chronic pain in the United States is estimated at $560 to $635 billion.

Prevalence
In the United States, an estimated 20% (50 million) of adults report some level of chronic pain on cross-sectional household surveys. The prevalence is higher among women and those with lower socioeconomic status (https://www.cdc.gov/mmwr/volumes/67/wr/mm6736a2.htm).

Etiology and Pathophysiology

  • With intense, repeated, or prolonged stimulation of damaged or inflamed tissues, the threshold for activating primary afferent pain fibers is lowered, the frequency of firing is higher, and there is an increased response to noxious and/or normal stimuli (peripheral and central sensitization). The amygdala, prefrontal cortex, and cortex relay emotions related to the pain experience, and these areas undergo structural and functional changes over time.
  • Patients often have an identifiable etiology, but pain levels can be worse than observable tissue injury. Many patients have no obvious source of chronic pain.

Genetics
A genetic polymorphism in opioid receptors may affect patient’s response to individual opioids.

Risk Factors

  • Traumatic: motor vehicle accidents, repetitive motion injuries, falls
  • Postsurgical: back surgeries, amputations, thoracotomies
  • Psychiatric comorbidities: substance abuse, depression, posttraumatic stress disorder (PTSD)

General Prevention

  • Prevent work-related injuries through ergonomic workplace design.
  • Varicella vaccine and rapid treatment of shingles to lower risk of postherpetic neuralgia
  • Tight glycemic control for diabetic patients, prevention of alcohol abuse, smoking cessation

Commonly Associated Conditions

Any chronic disease and/or its treatment can cause chronic pain.

There's more to see -- the rest of this topic is available only to subscribers.