Chronic Pain Management: An Evidence-Based Approach

Descriptive text is not available for this image BASICS

  • Chronic pain syndrome is when pain persists >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.
  • Management should be multimodal and include both pharmacologic and nonpharmacologic interventions.

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 (1).

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 socio-economic status (2)

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 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. Some patients may have no obvious source of chronic pain.

Genetics

Genetic polymorphisms may affect individual’s response to certain opioids (3).

RISK FACTORS

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

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 as well as management of substance use disorders

COMMONLY ASSOCIATED CONDITIONS

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

Descriptive text is not available for this image DIAGNOSIS

Chronic pain is the presence of unpleasant sensory and emotional experience lasting for >3 months. Two general categories of pain:

  • Nociceptive pain (response to tissue damage):
    • Somatic: skin, bone, soft tissue disease; described as well localized, sharp, stabbing, aching
    • Visceral: visceral inflammation/injury; described as poorly localized, dull, aching; may refer to sites remote from lesion; can wax and wane
  • Neuropathic pain: damaged peripheral or central nerves; described as burning, tingling, and/or numbness

HISTORY

  • Pain history: location, onset, intensity, duration, quality, temporal pattern, exacerbating agents, alleviators, prior treatments
  • Assess how pain affects patient’s functioning and quality of life.
  • Screen for personal or family history of substance use disorders and dependence, mental health conditions, and/or sexual abuse.
  • Standardized tools: pain severity—Brief Pain Inventory (short form); mood—Patient Health Questionnaire-9 (PHQ-9; https://www.apa.org/depression-guideline/patient-health-questionnaire.pdf)
  • Stratify patients who would be at increased risk of developing an opioid use disorder if opioids were indicated; substance abuse—Screener and Opioid Assessment for Patients with Pain (SOAPP; https://www.mcstap.com/docs/SOAPP-5.pdf)

PHYSICAL EXAM

Exam is guided by history and includes functional and behavioral assessments.

DIFFERENTIAL DIAGNOSIS

  • Complex regional pain syndrome is a disorder of a body region, which is characterized by pain, swelling, limited range of motion, vasomotor instability, skin changes, and bone demineralization. It frequently affects one body region and begins after a fracture, soft tissue injury, or surgery.
  • Aberrant drug-taking behaviors could be related to:
    • Inadequate analgesia, disease progression, opioid-resistant pain, opioid-induced hyperalgesia, opioid tolerance, substance use disorder, self-medication of non-pain symptoms, criminal intent (diversion), and poor health literacy

DIAGNOSTIC TESTS & INTERPRETATION

Base testing on history, exam, and differential diagnosis.

Initial Tests (lab, imaging)

  • Kidney and liver function should be evaluated prior to initiation of certain medications.
  • Urine toxicology screening & testing for those prescribed controlled substances to assess adherence to prescribed medications and to detect the presence of illicit substances:
    • The array of qualitative and quantitative analyses will be dependent on lab availability.
    • Qualitative analysis is a screening test and quantitative analysis is for confirmation of individual drug levels.
    • If you have questions about your toxicology test, contact the toxicologist associated with your lab.

Follow-Up Tests & Special Considerations

  • Depending on prescribed medications, patients may need follow-up kidney and liver function as well as toxicology testing.
  • For methadone, baseline ECG and annual ECG if methadone daily dose >120 mg or lower doses if prescribed multiple QT-prolonging medications

Diagnostic Procedures/Other

Consider interventional pain clinic for complex injections and nerve blocks.

Test Interpretation

  • Be aware of false positive and negative results of your screening or toxicology testing for commonly prescribed medications like SSRIs, sleep agents and over-the-counter medications like diphenhydramine.
  • Confirmatory and quantitative analysis should be performed if there is a positive qualitative result that may alter the treatment plan.

Descriptive text is not available for this image TREATMENT

GENERAL MEASURES

  • The goals of treatment are to restore function and decrease pain.
  • Treatment should be multimodal and include both pharmacologic and nonpharmacologic interventions.
  • Untreated sleep disorders or psychiatric conditions may make pain control more difficult, so these should be concurrently addressed.
  • Focus on disease-modifying treatment options (like allopurinol for gout).

MEDICATION

  • Management depends on type of pain (neuropathic vs. nociceptive).
  • Use sequential time-limited trials of medications; start at low doses, and gradually increase until effect or dose-limiting side effects are reached.
  • Combination acetaminophen/NSAID products with opioids can lead to serious acetaminophen/NSAID toxicities if patients exceed recommended doses. Patient and family education is critical.
  • Note: Be aware of implicit bias. People of color are at greatest risk for undertreatment regardless of pain type or type of analgesia.

First Line

  • For nociceptive pain:
    • Mainstay of treatment is NSAIDs: Avoid in kidney disease and heart failure. Most common side effect is GI distress/gastritis.
    • Topical agents: NSAIDs (diclofenac gel 1–3% BID), lidocaine (4% gel OTC is less effective but more affordable than 5% patch), capsaicin 0.035–0.100% QD to QID
  • For neuropathic pain:
    • Tricyclic antidepressants (desipramine [25 to 100 mg QD but start with 10 mg QD in frail elderly] and nortriptyline [25 to 100 mg QD but start with 10 mg QD in frail elderly]) or SNRI antidepressants (duloxetine 30 to 60 mg BID or venlafaxine 75 to 22 mg/day),
    • Anticonvulsants (gabapentin [initial dose 300 mg/day and titrate to max of 3,600 mg/day in 3 divided doses] and pregabalin [100 to 300 mg/day in 2 to 3 divided doses])
    • Recommend combining antidepressant or antiseizure medication with topical therapies like lidocaine or capsaicin.
  • Other agents:
    • Acetaminophen: daily dose not to exceed total 4 g in healthy adults and 2 g in elderly patients with hepatic disease or current/past alcohol use; acetaminophen has limited evidence in chronic pain management.

Second Line

  • For moderate to severe chronic pain
    • Morphine, oxycodone, hydromorphone, oxymorphone, fentanyl; check institutional opioid equianalgesic table.
      • Avoid morphine in patients with renal insufficiency.
      • Methadone should only be prescribed by experienced providers due to many drug interactions and risk of potentially fatal cardiac arrhythmias.
      • No evidence supports any of these opioids as superior to other or having improved side effect profile, however genetic polymorphisms do exist as aforementioned.
    • Buprenorphine (partial opioid agonist) has been found to reduce pain intensity for patients with chronic pain and can be more effective in patients without a history of opioid use disorder.
    • Once stable dose of opioids is established, change to sustained-release formulations if pain is likely to be long-term; short-acting formulations are for breakthrough/episodic pain only.
    • Common side effects: constipation, nausea, sedation, mental status changes, and pruritus; respiratory depression and opioid overdose are possible at any dose especially if combined with other centrally active agents
    • Co-prescribe nasal naloxone for patients on chronic opioids (see “Ongoing Care”).
  • Evidence on use of cannabis for chronic pain is low quality and controversial (4)[A].

ADDITIONAL THERAPIES

Nonpharmacologic interventions include the following:

  • Physical therapy
  • Psychological interventions: cognitive-behavioral therapy (CBT), patient and family education, relaxation techniques, mindfulness, and meditation
  • Acupuncture

SURGERY/OTHER PROCEDURES

Consider interventional procedures, including joint injections, nerve blocks, spinal cord stimulation, and intrathecal medication among others, as needed.

COMPLEMENTARY & ALTERNATIVE MEDICINE

  • For adults with chronic low back pain, consider mindfulness-based stress reduction (MBSR) or CBT.
  • Biofield therapies like Reiki, therapeutic touch are less well-studied but can be considered if the harm assessment is minimal for the individual patient.
  • Yoga as effective as standard physical therapy for moderate to severe chronic low back pain.

Descriptive text is not available for this image ONGOING CARE

FOLLOW-UP RECOMMENDATIONS

Patient Monitoring

  • Create a shared, written pain agreement outlining the frequency of follow-up visits, rate of toxicology testing, and discuss patient expectations for chronic pain management.
  • Patients should be reevaluated for safety and efficacy of the prescribed pain regimen.
  • Assess and document benefits, risks, pain levels, functioning, and quality of life.
  • Universal precautions:
    • Informed consent for opioid therapy; written agreement between patient and clinician
    • One prescriber and one pharmacy; no after-hours prescriptions or early refills
    • Mandatory police reporting for medication thefts; random urine drug tests, pill/patch counts
    • Continue with physical therapy, counseling, and psychiatric medications.
    • Participate in state’s prescription drug monitoring program: http://www.cdc.gov/drugoverdose/pdmp/index.html.
    • Taper and discontinue medications if patient does not benefit or if side effects outweigh benefits. If medications are abused or diverted, more rapid taper may be appropriate.
    • If substance use disorder is suspected, always offer treatment for substance abuse.
    • Tapering opioids should involve shared decision-making between patient and clinician with an individualized taper plan to each patient based on risks and benefits (5)[C].
    • Patients on long-term opioid therapy may see improvement in pain, function, and quality of life with voluntary dose reductions.
  • Nasal naloxone should be prescribed for all patients prescribed full agonist opioids.
    • Naloxone kit: two 1 mg/mL prefilled syringes with intranasal mucosal atomization device; takes effect in 2 to 5 minutes, lasts 30 to 90 minutes

PATIENT EDUCATION

American Chronic Pain Association: https://theacpa.org

COMPLICATIONS

  • Rate of addiction in chronic pain patients ~3–19%; aberrant medication-taking behaviors ~5%–24%.
  • Definitions
    • Substance use disorder: chronic biopsychological disease characterized by impaired control over drug use, compulsive use, and continued use despite harm.
    • Physical dependence: withdrawal syndrome produced by abrupt cessation or rapid dose reduction
    • Tolerance: state of adaptation when a drug induces changes that diminish its effects over time
    • Diversion: selling drugs or giving them to persons other than for whom they are prescribed

Authors

Laurel Banach, MD

REFERENCES

  1. Smith TJ, Hillner BE. The cost of pain. JAMA Netw Open. 2019;2(4):e191532. doi:10.1001/jamanetworkopen.2019.1532.  [PMID:30951152]
  2. Rikard SM, Strahan AE, Schmit KM, et al. Chronic pain among adults—United States, 2019–2021. MMWR Morb Mortal Wkly Rep. 2023;72:379–385.  [PMID:37053114]
  3. Vieira CMP, Fragoso RM, Pereira D, et al. Pain polymorphisms and opioids: an evidence based review. Mol Med Rep. 2019;19(3):1423–1434.  [PMID:30592275]
  4. Fisher E, Moore RA, Fogarty AE, et al. Cannabinoids, cannabis, and cannabis-based medicine for pain management: a systematic review of randomised controlled trials. Pain. 2021;162(Suppl 1):S45–S66.  [PMID:32804836]
  5. Dowell D, Ragan KR, Jones CM, et al. CDC clinical practice guideline for prescribing opioids for pain—United States, 2022. MMWR Recomm Rep. 2022;71(3):1–95.  [PMID:36327391]

Descriptive text is not available for this image CODES

ICD10

  • G89.29 Other chronic pain
  • G89.21 Chronic pain due to trauma
  • G89.28 Other chronic postprocedural pain

SNOMED

  • 82423001 Chronic pain (finding)
  • 431481001 chronic pain due to injury (finding)
  • 279047007 Persistent pain following procedure (finding)
  • 373621006 chronic pain syndrome (disorder)

CLINICAL PEARLS

  • Start with the foundational belief that a patient’s pain is real.
  • Emphasize that a pain-free life may not be possible—better function and quality of life are shared goals.
  • Use a multimodal approach with nonpharmacologic therapies and thoughtful medication use with clear goals, expectations, and documentation of care plan.
  • Universal precautions are a systems-based approach for opioid prescription in cases of chronic pain.

Last Updated: 2026

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