This management algorithm has been commissioned by Grünenthal Ltd, who also provided funding for its development. Grünenthal Ltd reviewed and approved the scope and pre-meeting documents, suggested a Chair and experts for the group, and put the algorithm through full medical approval to ensure its compliance with appropriate regulations; however, final editorial control has remained with the contributors and Guidelines. The views and opinions of the contributors expressed in this document are not necessarily those of Grünenthal Ltd, or of Guidelines, its publisher, advisers, or advertisers. 

Pharmacological management of chronic mixed pain in primary care

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Group members

  • Dr Victor Mendis (Chair, consultant in pain medicine and anaesthesia)
  • Dr Chandra Kanneganti (general practitioner)
  • Dr Mark Ritchie (general practitioner with special interest in pain management)
  • Dr Kim Rollinson (general practitioner)

Background

  • Chronic pain is a multifaceted disease; treatment aims to support initial symptom relief so that patients are sufficiently able to engage in non-pharmacological treatment 
  • Multi-modal treatment is often required due to the complexities of pain signalling and because mixed mechanisms often underlie chronic pain1
  • Analgesic agents with different mechanisms of action are increasingly used in combination to maximise efficacy and tolerability1—simple analgesics are often insufficient to provide adequate pain relief

Assessment

  • Assess patient’s chronic pain using a screening tool e.g. painDETECT for the likelihood of a neuropathic component:2
    • painDETECT 0–12 suggests that a neuropathic component is unlikely 
    • painDETECT 13–18 suggests that a neuropathic component may be present 
    • painDETECT 19–38 suggests that a neuropathic component is likely 
  • Use a tool such as the visual analogue scale (VAS)3 to assess pain intensity at each visit and make objective decisions regarding treatment

Pharmacological management

Chronic pain algorithm image

  • Agree a treatment plan with the patient, taking into account:
    • patient’s concerns and expectations 
    • pain components suggested by painDETECT 
    • severity of pain and its impact on lifestyle and daily activities (including sleep disturbance) 
    • underlying cause of pain and whether it has deteriorated 
    • physical and psychological problems 
    • co-morbidities and concurrent medications 
    • the benefits and possible adverse effects of the chosen treatment 
  • Select treatment pathway; nociceptive, neuropathic, or mixed, based on pain components as assessed using painDETECT, be aware of:
    • drug combinations that must be avoided/used with caution 
    • contraindications and/or precautions for individual medicines 
    • dose equivalence when switching between opioids, including codeine-containing compounds, which are converted to morphine in vivo, and transdermal opioid patches, taking total opioid dose into account (please refer to Table 1)4
  • Depending on individual circumstances, review patients at least 2–4 weeks after starting a new drug, either in person or by telephone consultation, and use VAS to assess pain control:
    • if mixed pain is not well controlled use painDETECT to assess possible changes in the nature of the pain and step up nociceptive or neuropathic treatment accordingly 
    • after 2 months of relative improvement in pain, attempt dose reduction or withdrawal
Table 1: Dose equivalence of opioids for oral administration (adapted from Opioids aware)4
Oral opioidEquivalent dose to 10 mg oral morphine
Codeine phosphate 100 mg
Dihydrocodeine  100 mg 
Morphine  10 mg
Oxycodone  5 mg 
Tapentadol  25 mg 
Tramadol  67 mg 

Non-pharmacological management

  • Consider organising or recommending non-pharmacological treatment, including: light exercise, physiotherapy, rehabilitation, and relaxation techniques, as appropriate 

Education

  • Explain to patients:
    • why a particular treatment is being used, for example, explain why a low-dose antidepressant is being prescribed for pain5
    • the importance of dosage titration and the titration process, providing individualised information and advice5
    • coping strategies for pain and possible adverse effects of treatment5
    • legal issues concerning driving when taking opioids or antidepressants, which may have potential for sedating effects (please refer to DVLA guidance)6

Box 1: painDETECT screening tool2

  • Simple, validated screening tool for identifying neuropathic pain
  • Takes the form of a questionnaire that can be completed in 1–2 minutes
  • Assessment is based entirely on patient responses—no need for examination to complete the questionnaire
  • Can be used by GPs:
    • in initial assessments to detect pain with a neuropathic component
    • in follow-up appointments to monitor progress 
  • painDETECT  score 0–12—neuropathic component is unlikely
  • painDETECT  score 13–18—neuropathic component may be present
  • painDETECT  score 19–38—neuropathic component is likely

Box 2: Treatment pathway for nociceptive pain based on the WHO analgesic ladder1,9

  • Step 1: non-opioid +/- adjuvant
  • Step 2: opioid for mild–moderate pain +/- non-opioid +/- adjuvant
  • Step 3: opioid for moderate–severe pain +/- non-opioid +/- adjuvant
  • NSAIDs may be used for the short-term treatment of pain with a predominantly inflammatory component—always use the lowest dose possible and take into account any contraindications

NSAIDs=non-steroidal anti-inflammatory drugs

Box 3: Treatment pathway for neuropathic pain

  • Amitriptyline, duloxetine, gabapentin, and pregabalin are all recommended by NICE as options for the pharmacological management of neuropathic pain5*
  • The group recommends:*
    • initial treatment with amitriptyline, if appropriate
    • switching to gabapentin if amitriptyline is not effective or not tolerated
    • switching to duloxetine if gabapentin is not effective or not tolerated
    • using gabapentin and pregabalin with caution due to the potential for misuse10,11

*In analgesia duloxetine is licensed for the treatment of diabetic peripheral neuropathic pain only and gabapentin is licensed for peripheral neuropathic pain—prescribers should always consult the relevant Summary of Product Characteristics (www.medicines.org.uk) before prescribing and follow relevant professional guidance.

Conflicts of interest

Dr Victor Mendis has received honoraria for services provided to Grünenthal Ltd; Dr Chandra Kanneganti, Dr Mark Ritchie, and Dr Kim Rollinson have received honoraria from Grünenthal for their work on this management algorithm.

References

  1. Scottish Intercollegiate Guidelines Network. Management of chronic pain. SIGN 136. SIGN, 2013. Available at: www.sign.ac.uk/sign-136-management-of-chronic-pain.html (accessed 1 February 2019).
  2. Freynhagen R, Baron R, Gockel U et al. painDETECT: a new screening questionnaire to identify neuropathic components in patients with back pain. Curr Med Res Opin 2006; 22 (10): 1911–1920.
  3. Hawker G, Mian S, Kendzerska T, French M. Measures of adult pain: Visual Analog Scale for pain (VAS), Numeric Rating Scale for Pain (NRS pain), McGill Pain Questionnaire (MPQ), Short-Form McGill Pain Questionnaire (SF-MPQ), Chronic Pain Grade Scale (CPGS), Short Form-36 Bodily Pain Scale (SF-36 BPS), and Measure of Intermittent and Constant Osteoarthritis Pain (ICOAP). Arthrit Care Res 2011; 63: S240–S252.
  4. Royal College of Anaesthetists. Opioids Aware. Available at: www.rcoa.ac.uk/faculty-of-pain-medicine/opioids-aware (accessed 1 February 2019)
  5. NICE. Neuropathic pain in adults: pharmacological management in non-specialist settings. Clinical Guideline 173. NICE, 2013 (last updated April 2018). Available at: www.nice.org.uk/guidance/cg173 (accessed 1 February 2019).
  6. Driver and Vehicle Licensing Agency. Miscellaneous conditions: assessing fitness to drive—medication effects. Available at: www.gov.uk/guidance/miscellaneous-conditions-assessing-fitness-to-drive#medication-effects (accessed 1 February 2019).
  7. Grunenthal Ltd. Palexia SR prolonged release tablets—summary of product characteristics. Available at: www.medicines.org.uk/emc/medicine/28373 (accessed 1 February 2019).
  8. Baron R, Likar R, Martin-Mola E et al. Effectiveness of tapentadol prolonged release (PR) compared with oxycodone/naloxone PR for the management of severe chronic low back pain with a neuropathic component: a randomized, controlled, open-label, phase 3b/4 study. Pain Pract 2016; 16 (5): 580–599.
  9. World Health Organization. WHO’s cancer pain ladder for adults. Available at: www.who.int/cancer/palliative/painladder/en/ (accessed 1 Februay 2019).
  10. Public Health England. Advice for prescribers on the risk of the misuse of gabapentin and pregabalin. Available at: www.gov.uk/government/publications/pregabalin-and-gabapentin-advice-for-prescribers-on-the-risk-of-misuse (accessed 1 February 2019).
  11. Mid Essex NHS Locality. Neuropathic pain. Mid Essex NHS Locality, 2017. Available at: https://midessexccg.nhs.uk/medicines-optimisation/clinical-pathways-and-medication-guidelines/chapter-4-central-nervous-system-2/172-pain-management-of-neuropathic-pain-sep-2009-1/file (accessed 1 February 2019).

This management algorithm has been commissioned by Grünenthal Ltd, who also provided funding for its development. Grünenthal Ltd reviewed and approved the scope and pre-meeting documents, suggested a Chair and experts for the group, and put the algorithm through full medical approval to ensure its compliance with appropriate regulations; however, final editorial control has remained with the contributors and Guidelines. The views and opinions of the contributors expressed in this document are not necessarily those of Grünenthal Ltd, or of Guidelines, its publisher, advisers, or advertisers.  

Job code: M-PLX-UK-08-19-0028 

Date of preparation: February 2019

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