Opioids in chronic non-malignant pain

This guideline is to aid primary care teams in managing patients, who have chronic pain, with opioids. This guidance should be used in conjunction with local and/or national guidance on the assessment of pain and with reference to British Pain Society Guidelines.

Key Points

• The aim of using opioids in the short to medium term is to support the rehabilitation and restoration of physical and mental function of patients.
• Clinical evidence has demonstrated that opioids can be useful in the management of chronic somatic, visceral and neuropathic pain.
• Opioids can also have untoward effects in terms of tolerance, dependence and addiction.

Before initiating opioids consider the following:  

• What is the cause (diagnosis) of persistent pain in your patient?
• Has a biopsychosocial assessment been made?
• Have other appropriate methods of pain management been tried? (e.g. other medications, graded exercises, pain management strategies, psychological methods)
• Does your patient have neuropathic pain? (Refer to NHSH neuropathic pain guidelines)
• Would a trial of opioids be suitable for this patient? (see below)

There are no chronic pain conditions in which opioids are completely contraindicated, however the boxes to the right are situations where they are not recommended or where closer monitoring would be required.

Consideration should be given to using the Opioid Risk Tool to assess for potential high risk/dependent patients. If patients are assessed as moderate to high risk closer monitoring will be required.

Prior to the commencement of opioid therapy, it is essential that appropriate informed consent is obtained from the patient and if necessary family/carers. The discussion should include;

• A clear explanation of the advantages and disadvantages of opioid therapy, which should include short term and long term side effects, potential for tolerance and addiction, detrimental impact on quality of life and advice on driving and operating machinery as per the British Pain Society Information Leaflet. http://www.britishpainsociety.org/
• Agreeing achievable patient specific goals. This may include an agreed expected reduction in pain score (30%), improvement in sleep pattern and functional ability. 
• An explanation of the concept of an Opioid Trial and what circumstances would surround the discontinuation of opioid medication.

Completion of the 1^st page of the ‘Progress Note’ Pain Assessment & Documentation Tool (PADT) to record baseline levels of the pain score and functional ability with help with assessment if treatment is been of benefit. http://www.healthinsight.org/Internal/assets/SMART/PADT.pdf.

Length of trial: Anticipated length of each opioid mediation trial would be 6 weeks.

Expectation: 30% improvement in pain and/or significant improvement in functional ability and sleep pattern.

• If no response with tramadol (after full titration) at 6 weeks stop and convert to morphine as described above.
• If tramadol is not tolerated due to side-effects, try sustained release morphine as described above
• Avoid using short acting opioid for breakthrough pain.
• If no response to MST (after full titration) after 6 week trial de-escalate dose by 10mg every week till stopped. This trial indicates that the patient pain is unlikely to be opioid responsive and this should be explained to the patient.
• Reassess the patient 1 to 2 weekly.
• Ensure most cost effective brands are used as identified from the NHSH Formulary.

Use of PADT tool for ongoing assessment is recommended (http://www.healthinsight.org/Internal/assets/SMART/PADT.pdf)

Assessment should include:

• Ongoing Efficacy – carry out recordings of pain score and functional assessment.
• If the opioid trial is not successful, discontinue opioid by tapering dose, reducing by 10mg of morphine every week till stopped.
• There are no high quality randomized controlled trials to suggest that one opioid is more effective than another. If there is NO clinical benefit with a full trial of one opioid, we would discourage further opioid trials in primary care – seek opinion of Chronic Pain Specialist. If opioid trial is successful, continue with monitoring of dose, pain score, function and side effects every 3 months initially until dose is stable, then every 6 months. Consider weaning opioids every 6 months to see if dose is still optimal.

• Keep daily dose of long acting opioid as low as possible.
• Measure sex hormones if patient reporting symptoms of hypogonadism and if abnormal seek advice from local endocrine clinic.
• Observe for signs of drug abuse. Refer to the Opioid Risk Tool. 

Constipation

The majority of patients taking opioids for moderate to severe pain will develop opioid induced constipation; tolerance does not develop to this side effect.¹ If increasing fluid and fibre intake is insufficient, guidelines suggest that the best prophylactic treatment for opioid induced constipation is a combination of a stimulant laxative and a stool softener.¹ Refer to NHSH formulary.

Nausea/Vomiting

Nausea and vomiting are common when starting on opioids but generally tolerance develops after 5 to 10 days.¹ It is recommended that patients commencing on an opioid for moderate to severe pain should have access to prophylactic antiemetics to be taken if required.¹ Refer to local formularies for treatment of choice. 

Itch

Opioid induced itch occurs in around 1% of those who receive a systemic opioid.  It is thought to be caused by a central mechanism rather than by histamine release, therefore in some cases antihistamines are not effective.⁴ Emollients should be used liberally if the patient has dry skin. Trial of a sedating antihistamine such as chlorphenamine or hydroxyzine is suggested, if this is not effective after a few days it should be stopped.⁶ 

For those patients with renal impairment, the likelihood of opioid toxicity with any opioid increases and the following guiding principles should be followed when prescribing opioids; 

• Use the smallest effective dose/frequency.
• Titrate carefully and monitor for adverse effects.
• If there are clinical concerns consult local renal specialists.
• If patient has significant renal impairment seek advice from Chronic Pain Service and or Renal Specialists.

Pain management in renal impairment guidance

For those patients with chronic non malignant pain you should be guided by individual circumstances and co-morbidities and need not follow guideline recommendations lower doses are likely to be used.

1. http://www.britishpainsociety.org/
2. http://www.healthinsight.org/Internal/assets/SMART/PADT.pdf
3. Sign 136 – Management of Chronic Pain December 2013
4. NHS Highland Formulary 2013 to 2015
5. BNF 69 – March 2015 to September 2015
6. Greater Glasgow Non Malignant Pain Opioid Prescribing Guideline - November 2014
7. Webster LR, Webster R, Predicting aberrant behaviours in Opioid treated patients: preliminary validation of the Opioid Risk Tool. Pain Medicine. 2005; 6(6):432

This table is an example for Primary Care clinicians to assess the strength of oral morphine between other forms of opioid medications available. This may help prescribers explain to patients the strength of their medication as many patients do not realise they are taking strong opioid medication until it is explained in the same strength as oral morphine.