What is the definition and management of chronic pain?

Definition of Chronic Pain

Chronic pain is defined as pain persisting for 3 months or longer beyond normal tissue healing time, as established by the International Association for the Study of Pain and endorsed by multiple major guideline societies. 1

Temporal Definition Across Guidelines

• The 3-month threshold is the most widely accepted standard across the American Heart Association, HIVMA/IDSA, American College of Physicians, and International Association for the Study of Pain guidelines 1

• Some older literature references variable durations (3-6 months), but contemporary consensus has standardized on 3 months as the defining timepoint 1, 2

• The American Geriatrics Society notes that "persistent pain" is the preferred terminology over "chronic pain" to avoid negative stereotypes, though both terms are used interchangeably in medical literature 1

Key Distinguishing Features

• Chronic pain persists beyond the expected period of tissue injury and repair, representing either ongoing injury or upregulation of the sensory system independent of active tissue damage 1

• The condition is characterized by functional and structural changes (neuroplasticity) in the central nervous system at every level, distinguishing it from acute pain 1, 2

• Chronic pain negatively affects an individual's wellbeing and is multifactorial in nature, involving biological, psychological, and social components 1, 3

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Management of Chronic Pain

Management requires identifying the pain mechanism (nociceptive, neuropathic, or centralized/mixed) and matching treatment to the specific pathophysiology, while simultaneously addressing psychosocial factors through a biopsychosocial approach. 1, 4, 3

Step 1: Classify Pain Mechanism

Nociceptive Pain (e.g., osteoarthritis, low back pain)

• First-line pharmacotherapy: NSAIDs and acetaminophen 5, 4
• Physical interventions including exercise therapy and epidural blockade for specific cases 5, 4

Neuropathic Pain

• First-line pharmacotherapy: Duloxetine, venlafaxine (SNRIs), gabapentin, pregabalin (α2δ ligands), or topical lidocaine 5, 4, 6
• Tricyclic antidepressants are also first-line options 5, 4, 3
• Opioids are second-line only for neuropathic pain with limited long-term effectiveness 5, 4

Centralized Pain/Central Sensitization (e.g., fibromyalgia)

• FDA-approved first-line treatments: Pregabalin, duloxetine, or milnacipran 5, 4, 6
• Cyclobenzaprine (muscle relaxant) is also effective 5
• Duloxetine 60 mg once daily is the optimal dose—trials show 120 mg provides no additional benefit but increases adverse effects and discontinuation rates 6
• Tramadol may be considered as an alternative 5, 4

Step 2: Avoid High-Risk Medications

• Never use benzodiazepines for chronic pain management—they lack analgesic efficacy, increase opioid overdose risk, cause anterograde amnesia, and are associated with long-term cognitive impairment and dementia 5

• Avoid opioid monotherapy as first-line treatment for chronic non-cancer pain due to limited long-term effectiveness and overdose risk, particularly when combined with benzodiazepines 1, 5, 4

Step 3: Integrate Non-Pharmacological Interventions

• Cognitive behavioral therapy (CBT) is essential to address pain catastrophizing, develop coping strategies, and manage comorbid depression/anxiety 4, 3

• Regular physical activity tailored to patient capabilities improves pain through multiple mechanisms including reduced inflammation, improved cardiovascular fitness, angiogenesis, and mitochondrial function 1, 4, 3

• Exercise therapy for conditions like peripheral artery disease shows that only 5-30% of pain improvement correlates with hemodynamic changes, indicating systemic adaptation mechanisms 1

• Physical therapy, education, and other self-management modalities remain underutilized despite proven effectiveness, often due to reimbursement obstacles 3

Step 4: Address Comorbidities Concurrently

• Screen for and treat comorbid depression, anxiety, sleep disturbance, and fatigue, which commonly accompany chronic pain and influence treatment outcomes 1, 4, 7

• Assess negative risk factors (mood/sleep disturbances) and positive resilience factors (social relationships, active coping) that interact with pain neurobiology 3

• Evaluate functional impairment, quality of life, and social environment as part of comprehensive assessment 3, 7

Common Pitfalls to Avoid

• Do not focus solely on pharmacological management—this approach fails to address physical function and psychological factors critical to outcomes 4, 3

• Do not assume pain intensity alone guides treatment—functional status, quality of life, and psychosocial factors are equally important outcomes 1, 3, 7

• Do not uptitrate duloxetine to 120 mg in non-responders to 60 mg—clinical trials demonstrate no additional benefit from dose escalation in fibromyalgia patients who fail to respond at 8 weeks 6

• Recognize that chronic pain requires long-term care with frequent reassessment and therapy adjustment, as cure is infrequent 7