Key Facts

Chronic pain is a major public health problem and a leading cause of disability worldwide. The paradigm has shifted from a biomedical model (find and fix the damage) to a biopsychosocial model (address the whole person).

Epidemiology

• ~28 million adults in the UK affected
• Prevalence increases with age, deprivation, female sex
• Accounts for significant NHS costs and work absence
• 7.8 million prescriptions for gabapentinoids in 2019 (a 150% increase over 5 years)

Pathophysiology

• Peripheral sensitisation: increased excitability of peripheral nociceptors
• Central sensitisation: enhanced CNS processing of nociceptive and non-nociceptive inputs
• Neuroplasticity: structural and functional brain changes maintain chronic pain
• Descending inhibitory pathway dysfunction: reduced serotonin/noradrenaline-mediated pain inhibition
• Psychological amplifiers: catastrophising, fear-avoidance beliefs, hypervigilance
• Social context: employment, relationships, benefits, litigation

Chronic Primary Pain

• Pain not explained by tissue damage or disease process
• Examples: fibromyalgia, chronic widespread pain, chronic primary headache, CRPS, chronic visceral pain
• Often associated with fatigue, sleep disturbance, mood changes
• Normal investigations

Chronic Secondary Pain

• Pain attributable to an underlying condition
• Musculoskeletal: OA, chronic back pain, RA
• Neuropathic: diabetic neuropathy, post-herpetic neuralgia, trigeminal neuralgia
• Post-surgical: persistent post-operative pain
• Cancer pain: tumour-related, treatment-related
• Visceral: chronic pancreatitis, endometriosis

Assessment

• Pain history: location, character, duration, aggravating/relieving factors
• Impact: sleep, mood, function, work, relationships
• Psychological assessment: PHQ-9 (depression), GAD-7 (anxiety), pain catastrophising scale
• Medication review: current analgesics, previous trials, opioid use
• Red flags: weight loss, night pain, neurological deficit (exclude serious pathology)

Red Flags

• New neurological deficit → structural cause
• Weight loss, night sweats → malignancy
• Fever → infection
• Worsening pain despite treatment → reassess diagnosis

For Chronic Primary Pain

• Limited investigations: avoid over-investigation (reinforces illness behaviour)
• Baseline bloods: FBC, ESR/CRP, TFTs, calcium, vitamin D, HbA1c – to exclude secondary causes
• Imaging ONLY if red flags or specific indication

For Chronic Secondary Pain

• Guided by underlying condition: X-ray, MRI, nerve conduction studies, etc.
• Neuropathic pain assessment: LANSS score, DN4 questionnaire

Psychological Assessment

• PHQ-9: depression screening
• GAD-7: anxiety screening
• Pain Catastrophising Scale
• Brief Pain Inventory: pain severity and interference

Chronic Primary Pain (NICE NG193)

Recommended:

• Supervised group exercise programmes: most effective intervention; aerobic and strength
• Psychological therapies: CBT, acceptance and commitment therapy (ACT)
• Acupuncture: single course may be offered
• Antidepressants (amitriptyline, duloxetine, SSRI/SNRI): ONLY if comorbid depression/anxiety; NOT for pain alone

NOT recommended for chronic primary pain:

• Paracetamol, NSAIDs, opioids, gabapentinoids, benzodiazepines, corticosteroid injections, ketamine, antiepileptics

Chronic Secondary Pain

Neuropathic pain (NICE CG173):

• Amitriptyline 10-75mg or duloxetine 60-120mg or gabapentin 300-3600mg or pregabalin 150-600mg: first-line options
• Topical capsaicin or lidocaine patches: localised neuropathic pain
• Tramadol: short-term, cautious use

Musculoskeletal pain:

• Exercise, physiotherapy
• Topical NSAIDs, oral NSAIDs (short-term)
• Intra-articular injections where appropriate

Opioid Deprescribing

• Gradual dose reduction: typically 10% per week/fortnight
• Patient education: explain rationale (no long-term benefit, harm reduction)
• Support: psychology, pain management programme
• NICE: do not initiate opioids for chronic primary pain

Pain Management Programmes

• Multidisciplinary: physiotherapy, psychology, occupational therapy, pharmacy, nursing
• Group-based: peer support, shared experience
• Goals: improve function and quality of life (not eliminate pain)
• Evidence base: strongest for chronic primary pain/fibromyalgia

Referral Criteria

• Chronic pain significantly impacting function → pain management team
• Diagnostic uncertainty → rheumatology (one-off assessment)
• Significant psychological comorbidity → psychology/psychiatry
• Opioid dependence → addiction services

• Chronic primary pain: chronic condition; complete resolution uncommon
• Self-management: patients who engage with exercise and psychological strategies have the best outcomes
• Pain management programmes: 50-60% report meaningful improvement in function and quality of life
• Opioids: long-term use associated with worsening outcomes, not improvement
• Return to work: a key prognostic indicator; prolonged absence worsens outcomes
• Neuropathic pain: ~50% achieve ≥50% pain reduction with appropriate pharmacotherapy

NICE NG193 Key Recommendations Summary

WHO Pain Ladder (Modified for Non-Cancer Pain)

• Step 1: Paracetamol, NSAIDs
• Step 2: Weak opioids (codeine, tramadol) – increasingly questioned
• Step 3: Strong opioids – NOT recommended for chronic non-cancer pain
• Modern approach: multimodal (physical + psychological + pharmacological)