Clinical Notes : Pharmacology
204. Chronic Pain and Opioids
Chronic pain management
Chronic pain, that is pain lasting for longer than 12 weeks, is a major clinical challenge, with an increasing incidence in an ageing population, often alongside other co-morbidities.(1)
In the UK, a recent systematic review and meta-analysis of population studies found a prevalence of 43%. (2)
Around 14% of people, particularly women and older adults, report ‘significant chronic pain’, which requires treatment and support.(3)
Chronic pain has a negative effect on individuals, their families, and their carers, creating a large societal burden, and a coordinated approach is needed to address this.
Modern pain management uses a biopsychosocial approach, in which careful assessment of all aspects is required to formulate a multidisciplinary management plan.
It is unlikely that analgesics alone will provide effective management, optimise successful outcomes, or minimise long-term harms.
Despite this, the use of opioids for chronic, non-malignant pain has increased dramatically over the last two decades.
In the US, where opioid prescribing increased steadily from 2006, peaking in 2012 at a rate of 81.3 prescriptions per 100 patients,(4) it has been termed an ‘epidemic’ by the US Surgeon General.(5)
Mortality associated with unprescribed and prescribed opioids is a major problem in the US, where deaths from prescription opioids have increased by almost 400% since 1999.(6–8)
The prescribing rates of strong opioids more than doubled in Scotland between 2002 and 2012, although there was marked regional variation and an association with deprivation, similar to that seen in England.
Not only has there been an increase in the number of prescriptions for opioids, but also an increase in the morphine equivalent doses prescribed.(9–11)
The reasons for these increases are complex and include:
the introduction of pain as the fifth vital sign by the American Pain Society (12)
new opioids and/or formulations becoming available
changes in societal expectations
historical recommendations of specialist medical societies
the concept that opioids used for pain relief would not result in addiction, and the introduction of the term ‘pseudo-addiction’, despite little in the way of scientific evidence.(13,14)
1. Know what the evidence says about opioid use
It is important to consider how the evidence about chronic pain management and particularly the use of opioids has evolved.
When the Scottish Intercollegiate Guidelines Network (SIGN) published its first guideline on the management of chronic pain (1) in 2013, the evidence for opioid use for chronic pain was assessed. (15)
This included evidence for efficacy compared with placebo, as well as information about adverse events regarding strong opioids, plus tramadol, codeine, and compound preparations. Parenteral and neuraxial routes of administration were excluded.(1)
Previously, one of the key recommendations was that strong opioids should be considered for chronic lower back pain or osteoarthritis, and only continued if there was ongoing pain relief.
Regular review was recommended.(1,15)
This recommendation is no longer current; it was also noted that there were deficiencies in the evidence, with no good quality randomised controlled trials (RCTs) beyond 6 months of use, as well as a likelihood of overestimation of treatment effect because of the type of analysis used.(1)
In August 2019, the opioids section of SIGN 136 was updated to reflect significant changes in the evidence base, with an alteration in the balance of risks and benefits (Figure 1).(1)1
A wide body of literature explores the harms associated with long-term opioid use, which include addiction and misuse, tolerance, endocrine dysfunction, increased risk of cardiovascular events, and being involved in a road traffic incident. (16,17) Despite this, it was not until 2018 that the first longer-term RCT was published, comparing opioid with non-opioid analgesics in the management of chronic back pain, or hip or knee osteoarthritis pain.(18)
In this study, patients who were on opioids for 12 months were found to have worse pain, with no improvement in function, compared with those on non-opioid analgesics (see Figure 1).(18)
Figure 1 : The balance of evidence for long-term strong opioid use in chronic pain
2. Prescribe opioids in line with restrictions
In light of the accumulated change in evidence, the 2019 version of SIGN 136 includes new recommendations around opioid use, which place more restrictions around indications and duration of use (see Box 1)
3. Consider non-pharmacological management strategies
The updated SIGN 136 guideline recommendations echo a 2018 position statement by the International Association for the Study of Pain (IASP), (19) which reiterates the importance of continued access to opioids for acute pain management, but advises caution when these are used for chronic pain.
Similarly to the SIGN 136 guideline update, short- to medium-term use of low-dose opioids in selected, well-monitored patients is presented as an option, but other strategies combining physical and behavioural therapies are preferred, with stronger evidence of efficacy and a low risk of harm. (19,20)
4. Assess suitability and monitor carefully when prescribing strong opioids
The SIGN pathway for using strong opioids in patients with chronic pain has also been updated to reflect the new recommendations, and provides practical guidance about how and when to start strong opioids.
The pathway (summarised in Figure 2) is broken down into three sections, which focus on:(1)
assessing suitability for strong opioid use
starting a strong opioid
monitoring opioid trial.
Strong opioids should not be commenced until there has been a careful assessment of the patient and a discussion about when to stop treatment. Treatment should be titrated to the lowest effective dose, balanced against side-effects, and reviewed regularly.
Figure 2 : Key features of opioid use pathway
5. Use non-pharmacological approaches and support self-management
Although the other sections of SIGN 136 have not been updated, the importance of an integrated multidisciplinary approach remains central to the management of people with chronic pain.
This approach should be based on a biopsychosocial assessment to formulate a management plan, using pharmacological management when appropriate, alongside physical and psychological therapies, and supported self-management. In general, avoid using strong opioids as the main treatment approach.
On a positive note, more recent analyses have indicated a stabilisation or even decrease in opioid prescribing rates in Scotland (21) and in the US, where prescription behaviour surveillance systems have been implemented. (22)
The focus, however, should not just be on a reduction in prescribed opioids with no alternative strategies.
Health and social care services need to meet the requirements of people with chronic pain, providing easy access to evidence-based social prescribing and non-pharmacological management.
Alongside this, continued research into novel analgesics that reduce pain with minimal adverse effects from long-term use and careful evaluation of non-pharmacological interventions will help to reduce the overall burden of chronic pain.
In conclusion, opioid use for chronic pain is now recommended under much more restricted conditions than previously.
This is because of an increase in the evidence around potential significant harms, and emerging evidence about limited long-term efficacy, although further research is needed in this area. Importantly, opioids should not be used as a single strategy in chronic pain management, but as part of a wider plan, with careful assessment and review throughout the period of use.
Non-pharmacological approaches, including strategies to support increases in physical activity, should form a key component of chronic pain management, to improve function and quality of life.
1. Scottish Intercollegiate Guidelines Network.
Management of chronic pain. SIGN 136.
Edinburgh: SIGN, 2013, updated 2019.
2. Fayaz A, Croft P, Langford R et al.
Prevalence of chronic pain in the UK: a systematic review and meta-analysis of population studies.
BMJ Open 2016; 6: e010364.
3. Smith B, Elliott A, Chambers W et al.
The impact of chronic pain in the community.
Fam Pract 2001; 18 (3): 292–299.
4. Centers for Disease Control and Prevention.
Online. Accessed 30 March 2020
5. US Department of Health and Human Services, Office of the Surgeon General.
Facing addiction in America—the Surgeon General’s spotlight on opioids.
Washington DC: DHHS, 2018.
Online. Accessed 30 march 2020
6. National Institute on Drug Abuse.
Overdose death rates. www.drugabuse.gov/related-topics/trends-statistics/overdose-death-rates
Online. Accessed 30 March 2020
7. Benzon H, Anderson T.
Themed issue on the opioid epidemic: what have we learned? Where do we go from here?
Anes Analg 2017; 125 (5): 1435–1437.
8. Huang X, Keyes K, Li G.
Increasing prescription opioid and heroin overdose mortality in the United States, 1999-2014: an age-period-cohort analysis.
Am J Public Health 2018; 108 (1): 131–136.
9. Torrance N, Mansoor R, Wang H et al.
Association of opioid prescribing practices with chronic pain and benzodiazepine co-prescription: a primary care data linkage study.
Br J Anaesth 2018; 120 (6): 1345–1355.
10. Mordecai L, Reynolds C, Donaldson L, de C Williams A.
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11. Curtis H, Croker R, Walker A et al.
Opioid prescribing trends and geographical variation in England, 1998-2018: a retrospective database study.
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12. Campbell J. APS 1995 presidential address.
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13. Greene M, Chambers R.
Pseudoaddiction: fact or fiction? An investigation of the medical literature.
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14. Portenoy R, Foley K.
Chronic use of opioid analgesics in non-malignant pain: report of 38 cases.
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15. Smith B, Hardman J, Stein A, Colvin L; on behalf of the SIGN Chronic Pain Guideline Development Group.
Managing chronic pain in the non-specialist setting: a new SIGN guideline.
Br J Gen Pract 2014; 64 (624): e462–e464.
16. Dowell D, Haegerich T, Chou R.
CDC guideline for prescribing opioids for chronic pain—United States, 2016.
JAMA 2016; 315 (15): 1624–1645.
17. Chou R, Turner J, Devine E et al.
The effectiveness and risks of long-term opioid therapy for chronic pain: a systematic review for a National Institutes of Health Pathways to Prevention Workshop.
Ann Intern Med 2015; 162 (4): 276–286.
18. Krebs E, Gravely A, Nugent S et al.
Effect of opioid vs nonopioid medications on pain-related function in patients with chronic back pain or hip or knee osteoarthritis pain: the SPACE randomized clinical trial.
JAMA 2018; 319 (9): 872–882.
19. International Association for the Study of Pain. IASP statement on opioids.
20.Geneen L, Moore R, Clarke C et al.
Physical activity and exercise for chronic pain in adults: an overview of Cochrane Reviews.
Cochrane Database Syst Rev 2017; (4).
21. Information Services Division, NHS National Services Scotland.
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22. Strickler G, Kreiner P, Halpin J et al.
Opioid prescribing behaviors—prescription behavior surveillance system, 11 states, 2010–2016.
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