Control of pain in general practice - Dr I Mohamed & Dr G Baranidharan

Pain is the commonest symptom described in outpatient clinics⁽¹⁾. A systematic review and meta-analysis of population studies revealed chronic pain prevalence in UK of 43%, which increases further to 62% of the population over the age of 75⁽²⁾. It has major clinical, social and economic implications. For instance its impact on economy is greater than that of most other health conditions due to its effect on rates of work absences and reduced levels of productivity. Chronic pain management can be very challenging with variable response from patients, however the extent of suffering and the poor quality of life experienced by some warrants pain relief being considered as a universal human right⁽³⁾.

Pain is defined by the International Association for the Study of Pain (IASP) as ‘An unpleasant sensory and emotional experience associated with actual or potential tissue damage, or described in terms of such damage’. It can be classified based on time scale into Acute or Chronic. Acute pain being that which decreases shortly after onset and resolves once healing is complete. On the other hand chronic pain usually persists for longer than expected after healing has occurred. This is generally but not strictly speaking more than 12 weeks period.

Chronic pain consists of a wide spectrum of syndromes secondary to varying pathologies. It can be broadly classified into^(4,5):

Musculoskeletal (Mechanical): Such as Rheumatoid arthritis, osteoarthritis, osteomyelitis, osteoporosis, myositis, myalgia or lower back pain (secondary to disc prolapse, facet joint or sacroiliac joint disease).
Neuropathic pain: Such as diabetic neuropathy, post-herpetic neuralgia, trigeminal neuralgia, complex regional pain syndrome, radicular pain, post-surgical chronic neuropathic pain, and neuropathic cancer pain. Examples of conditions that can cause central neuropathic pain include stroke, spinal cord injury and multiple sclerosis. Neuropathic pain can be intermittent or constant, spontaneous or provoked. Typical descriptions of the pain include terms such as shooting, stabbing, like an electric shock, burning, tingling, tight, numb, prickling, itching and a sensation of pins and needles. People may also describe symptoms of allodynia (pain caused by a stimulus that does not normally provoke pain), hyperalgesia (an increased response to a stimulus that is normally painful), anaesthesia dolorosa (pain felt in an anaesthetic [numb] area or region), and sensory gain or loss (IASP 2011).
Chronic headache: Such as Migraine, cluster, tension analgesic overuse and post trauma.
Fibromyalgia: Chronic widespread pain with multiple tenderness over many body areas. It affects connective tissues such as muscles, tendons and ligaments.
Visceral pain: Such as pain arising from abdominal, pelvic or thoracic viscera.

Assessments

Assessment of chronic pain is multidimensional. It is well simplified by the ‘4 Ps’ described by Aston Wan⁽⁶⁾:

Pain: Nature and possible etiological pathology
Past medical history: Comorbidities affecting pain or its management.
Performance/functional status: Important as a baseline measure when deciding treatment options and when assessing response.
Psychological/Psychiatric: Depression can coexist with chronic pain making its treatment more difficult.

Management of chronic pain can be very challenging as mentioned earlier. In addition elimination of pain is often very difficult to achieve and in some cases virtually impossible. Therefore the focus of treatment shoudl be on improving function and quality of life rather than treating the pain alone. A different set of ‘4 Ps’ can help in management as describe by A Wan⁽⁶⁾:

Physical: Exercise and physiotherapy play huge part in managing chronic pain.
Psychological: Pain education, fear, anxiety and stress management. Cognitive behavioural therapy, mindfulness and pacing activities.
Pharmacological: Options include analgesics described in the WHO pain ladder such as Paracetamol, NSAID, and weak/strong opioids. Others include adjunctive treatment such as steroid, anti-inflammatory, antidepressants and antiepileptic drugs. It’s crucial to consider potential side effect when prescribing any drug, especially long term therapy such as opioid for chronic pain. A useful guide titled ‘Opioids Aware: A resource for patients and healthcare professionals to support prescribing of opioid medicines for pain’⁽⁷⁾ highlights the following key recommendations:

Opioids are very good analgesics for acute pain and for pain at the end of life but there is little evidence that they are helpful for long-term pain.
A small proportion of people may obtain good pain relief with opioids in the long-term if the dose can be kept low and especially if their use is intermittent (however it is difficult to identify these people at the point of opioid initiation).
The risk of harm increases substantially at doses above an oral morphine equivalent of 120mg/day, but there is no increased benefit.
If a patient is using opioids but is still in pain, the opioid are not effective and should not be discontinued, even if no other treatment is available.
Chronic pain is very complex and if patients have refractory and disabling symptoms, particularly if they are on high opioid doses, a very detailed assessment of the many emotional influences on their pain experience is essential.

Procedure/intervention: Can be considered in selected number of patients. This applies to TENS, acupuncture, nerve blocks, joint injections, trigger point injections, nervious system stimulators/pumps as well as surgery.

Consider referring the person to a specialist pain service and/or a condition-specific service at any stage, including at initial presentation and at the regular clinical reviews if⁽⁴⁾:

They have severe pain or
Their pain significantly limits their lifestyle, daily activities (including sleep disturbance) and participation or
Their underlying health condition has deteriorated.

Progress assessment is very important. Here the ‘6 As’ recommended by Gourlay et.al⁽⁸⁾ are useful:

Activities: Clarify if any improvement in functional status
Analgesia: Assess objectively with tools of scoring systems such as visual analogue scale, numeric rating scale or brief pain inventory.
Adverse effects: From treatment provided
Aberrance behaviour: This can occur from drugs such as opioids or benzodiazepines such as unsanctioned dose escalations, reported missing scripts, possible inappropriate uses, diversions and possible overuse/overdose.
Affect: Assess mood to plan if psychological input is required.
Adequate documentation: Is mandatory for good clinical practice and medico-legal aspect

In summary, pain management should focus on trying to identify the type of pain, analgesic agents should be reassessed and reduced when the pain is under control.

References

Surah A, Baranidharan G, Morley S. Chronic pain and depression. Continuing Education in Anaesthesia Critical Care & Pain, 2014, 14(2), 85-89.
Fayaz A, Croft P, Langford R M, et al. Prevalence of chronic pain in the UK: a systematic review and meta-analysis of population studies. BMJ Open, 2016;6:e010364. doi:10.1136/ bmjopen-2015- 010364
Phillips CJ. The Cost and Burden of Chronic Pain. Reviews in Pain. 2009, 3(1), 2-5.
National Institute for Health and Clinical Excellence (2013) Neuropathic pain in adults: pharmacological management in non-specialist settings. Clinical guideline (CG173).
Chhabra G. Chronic pain syndromes. BMJ Best Practice. Last accessed 01 October 2017.
Wan A. GP pain management: What are the ‘Ps’ and ‘As’ of pain management?. Australian Family Physician. 2014, 43(8), 537-540.
Opioids Aware: A resource for patients and healthcare professionals to support prescribing of opioid medicines for pain. https://www.rcoa.ac.uk/ faculty-of-pain-medicine/opioids-aware (assessed 01/10/2017).
Gourlay DL, Heit HA, Almahrezi A. Universal precautions in pain medicine: a rational approach to the treatment of chronic pain. Pain Medicine. 2005, 6, 107–112

Content provided by:

Dr I Mohamed
specialist registrar in anaesthesia

Dr Ganesan Baranidharan
consultant in anaesthesia and pain management
MBBS FRCA FCARCSI