Management of chronic non-cancer pain in primary care

Opening Vignette

Mrs Yeo, a 68-year-old woman, came to you for chronic back pain, which had been persistent for the past year. She had been doctor-hopping, hoping to find an effective pain relief. About 6 months ago, she visited an orthopaedics specialist, who diagnosed her with degenerative disc disease and offered surgery, but she was not keen. Due to the back pain, Mrs Yeo stopped her part-time job 3 months ago and had been staying home more often instead of participating in community activities or interacting with her neighbours. She expressed hopelessness and lamented about the impact of the back pain on her function and lifestyle.

WHAT IS CHRONIC PAIN?

Chronic pain refers to pain that lasts for more than 3 months and persists past normal healing time. According to the International Association for the Study of Pain, pain is defined as “an unpleasant sensory and emotional experience associated with, or resembling that associated with, actual or potential tissue damage“. It is always a personal experience that is influenced to varying degrees by biological, psychological and social factors.[1] The perception of pain is often affected by personal life experiences, emotional factors, personal belief systems and family upbringing and values.

HOW COMMON IS THIS IN MY PRACTICE?

About 8.7% of the Singapore population experiences chronic pain.[2] Within this subset, a higher prevalence of chronic pain is present among females (10.9%) and it increases significantly among people above 65 years old. Chronic pain is a risk factor for psychological disorders. A Singapore cross-sectional epidemiological survey showed that chronic pain is significantly associated with major depressive disorder (odds ratio 2.4) and generalised anxiety disorder (odds ratio 3.0).[3] The economic effects of chronic pain are substantial. Another local cross-sectional study showed that episodic migraine alone posed an economic burden of SGD 1 billion per year, translating to about 2% of total government healthcare expenditure in Singapore.[4]

HOW RELEVANT IS THIS TO MY PRACTICE?

With Singapore's ageing population, the prevalence of chronic pain is expected to increase, and it will be beneficial for family physicians (FPs) and general practitioners (GPs) to manage uncomplicated chronic pain conditions. Complex cases may still eventually require a pain specialist's review.

Chronic pain is challenging to manage in primary care. Although there are few studies conducted on the local practice of chronic pain management, some common barriers have been identified. In a local qualitative study, fellow physicians in Singapore shared that a considerable number of physicians still view chronic pain in a biomedical model rather than a biopsychosocial model. In addition, the older community often feels stigmatised or views it negatively when offered psychological treatments for chronic pain. This lack of public awareness also deters physicians from referring older persons for psychological treatment. Keeping a close and therapeutic relationship with patients, involving the family members and having consistent graduated patient education on the multifaceted nature of chronic pain were found to be helpful.[5] In our local context, chronic pain management may incur considerable costs, especially in the aspect of psychological treatment, which may not be covered under government subsidy schemes such as Medisave. This, in turn, can further deter patients from pursuing holistic treatment. FPs and GPs can look into these factors and better reach out to patients.

In this article, we aim to shed light on the range of management strategies available to manage chronic pain conditions [Box 1]. Chronic pain management is complex to manage in a primary care setting and it often requires multidisciplinary co-management (FP or GP, pain specialist, physiotherapist, occupational therapist and psychologist) with the necessary patient empowerment and link-up with community resources.

Box 1.

Common chronic non-cancer pain conditions.

Arthritis

Spinal stenosis

Spinal spondylosis

Diabetic neuropathy

Post-injury complex regional pain syndrome

Post-herpetic neuralgia

Trigeminal neuralgia

Chronic pelvic pain

Fibromyalgia

WHAT CAN I DO IN MY PRACTICE?

Chronic and acute pain management has some similarities, although their management differs in some regard due to the different pathophysiologies. Besides the underlying nociceptive or neuropathic pain, the perception of pain and suffering is often contributed by psychological factors, personal beliefs, life experiences and social factors such as financial struggles or litigation.[6] It should be ingrained into our daily practice to elicit and address the root causes to manage chronic pain effectively.

Figure 1 shows a brief overview of an approach that can be applied in primary care. For patients with chronic pain lasting from months to years, the priority is not to eliminate pain completely, as this is often ambitious to achieve, but to improve function and quality of life. Chronic pain should be treated with a multimodal 4 'P's approach, which are Pharmacological and non-pharmacological (Physical, Psychological and Procedural) strategies. These strategies can be initiated early and concurrently for greater effectiveness and to instill confidence in the doctor–patient relationship.

Figure 1.

Chart shows the overview of approach to chronic pain in primary care.

Non-pharmacological therapy

The pathophysiology in chronic pain commonly involves central sensitisation and may be associated with underlying psychiatric conditions. Chronic pain management can be effective with non-pharmacological interventions such as physiotherapy, yoga, mindfulness, exercise, heat and cold application therapy, acupuncture, patient education and empowerment. However, the effect of these interventions was reported to be either immediate or short term, which suggests that non-pharmacological interventions should be done regularly for a sustained effect.[7] A typical physiotherapy course consists of two or three sessions each week for a duration of 8–12 weeks. Failure to show improvement within this time frame should prompt the physician to reconsider if physiotherapy is still recommended.[8] However, in the local context, due to exceeding demand for subsidised physiotherapy services, public healthcare institutions are unable to accommodate two or three sessions per week for each patient. These limited resources can be made more available and efficient by educating and empowering patients with the right mindset and attitudes towards exercise regime. Empowerment can further enable patients to sustain the efforts and reap its benefits.

Pharmacological therapy

Chronic pain can be broadly classified into nociceptive pain and neuropathic pain. Generally, nociceptive pain is sharp and well localised, while neuropathic pain is characterised by paraesthesia (numbing, shooting, cramping sensation) and may be poorly localised. Occasionally, patients may present with both nociceptive and neuropathic pain. Among patients who have end-stage knee or hip osteoarthritis, which is traditionally understood as nociceptive pain, about 35% of women and 27% of men have pain features that are suggestive of neuropathic knee pain.[9]

This dichotomy can assist FPs and GPs to prescribe the appropriate pharmacological therapy. Typically, all pain should be treated according to the World Health Organization (WHO) pain guidelines, starting with non-opioid modalities to weak opioids and escalating to opioid therapy, with gabapentinoids and antidepressants conventionally reserved for neuropathic pain. If the pain is mild, a single analgesia can be given. For moderate or severe pain, combining multiple analgesic agents should be considered. These combination therapies have synergistic effects, which allow for lower doses of each analgesia and reduce the risks of adverse effects of each analgesia. When initiating treatment, the efficacy can be assessed after 2–4 weeks. If deemed ineffective, the medication can be switched to an alternative agent, reduced or withdrawn.

The effect of pharmacological therapy is short-lived, and this may encourage patient reliance on medications in the long term, leading to higher risks of adverse effects. Hence, treatment often needs to be individualised, directed according to patients' functional limitations and goals, and kept as short a period as possible [Table 1].

Table 1.

Overview of common non-opioid pharmacological agents.[10]

Neuropathic pain*
Anticonvulsants
Gabapentin	Gabapentin can be initiated at a low dose of 100-300 mg at bedtime with gradual increases, up to a maximum dose of 3,600 mg per day. FDA-approved for post-herpetic neuralgia.
Pregabalin	Pregabalin can be initiated at 50 mg three times a day or 75 mg two times a day or 150 mg at bedtime, with gradual increases up to a maximum dose of 300 mg two times a day. FDA-approved for post-herpetic neuralgia and painful diabetic neuropathy.
Antidepressants
Duloxetine	Duloxetine can be initiated at a lower dose of 30 mg daily for a week, followed by an increase to the usual dose of 60 mg daily to reduce the side effects. It can be increased gradually up to a maximum dose of 120 mg daily. FDA-approved for painful diabetic neuropathy.
Venlafaxine	Venlafaxine can be prescribed at 75-225 mg daily, with no fixed dosage recommended. Various dosages were used in multiple trials and no recommendation on its dosage and regime can be concluded. It is an off-label use.
Amitriptyline	Amitriptyline can be initiated at 10-25 mg daily at bedtime with gradual increments by 10-25 mg every 1-2 weeks up to 150 mg per day in a single dose or in two divided doses. It is an off-label use.
Nociceptive pain
Anticonvulsants	Gabapentin can be initiated at 100-300 mg daily and increased gradually to a maximum dose of 1.2-2.4 g daily in divided doses. It is an off-label use for fibromyalgia.
Antidepressants	Duloxetine can be initiated at 30 mg daily for 1 week and then increased gradually to a maximum dose of 60 mg daily. It is used for fibromyalgia, and as an alternative agent for back pain, neck pain and osteoarthritis of the knee.
Acetaminophen
NSAIDS

*Examples include post-herpetic neuralgia and diabetic peripheral neuropathy. FDA: US Food and Drug Administration, NSAIDs: nonsteroidal anti-inflammatory drugs

Opioid therapy

Discussion surrounding opioid therapy should include the common side effects and the increased risks of opioid dependence and abuse. In line with the recent release of the Ministry of Health Opioid Guidelines, long-term opioid therapy should not be routinely prescribed.[11] If a patient is started on opioid therapy, regular assessments of the patient's response should be conducted. The doctor should consider ceasing the therapy if there is no improvement in the quality of life or achievement of functional outcomes, or if there is any suspicion of abuse.

The risk factors of opioid therapy include developing comorbidities such as major depression and psychosis, suicidal tendencies and substance abuse. There are several scoring systems for prediction of aberrant use before initiation of opioid therapy, such as the 'Opioid Risk Tool' and the 'Screener and Opioid Assessment for Patients with Pain' (SOAPP).[12] With these screening tools, the risks of aberrant behaviour from opioid use can be stratified as low risk, moderate risk or high risk. Low-risk patients are generally deemed reasonable to start opioid therapy in primary care. High-risk patients should be referred to pain specialist for further management.

Procedural treatment

Lastly, there are various types of procedures that can help manage chronic pain, such as injections and nerve blocks. Patients who are suffering from chronic back pain due to disc herniation, spinal stenosis, discogenic pain or post-surgery syndrome may benefit from having epidural injections.[13] There is debatable evidence for intra-articular injectables for the management of chronic knee osteoarthritis.[14] Timely referral to tertiary pain specialists and, hence, access to these procedures can help to provide synergistic effort in managing chronic pain. As a result, patients can achieve significant improvement in pain control, which will strengthen their adherence to subsequent treatments.

HOW CAN I PROVIDE MORE HOLISTIC MANAGEMENT?

Patients with chronic pain often have associated psychological complications such as depression and anxiety, and face social issues such as unemployment. This is especially prominent among patients with a low socioeconomic status. A local study showed that a person with chronic pain is twice as likely to face unemployment compared to a person of similar socioeconomic status without chronic pain.[15] It is challenging for FPs and GPs to thoroughly address these issues in a time-efficient manner. However, FPs and GPs can value-add by improving communication with tertiary centres, highlighting new issues and working together to best manage these psychosocial issues.

There are several support groups available for patients and their caregivers, such as the Knee Osteoarthritis Improvement Group for patients with knee osteoarthritis and the Autoimmune Diseases Support Group for patients with rheumatoid arthritis. TOUCH Community Services also has a community musculoskeletal clinic which is mainly run by physiotherapists.

Patients facing employment woes can also approach government agencies such as Workforce Singapore, which provides training opportunities, career guidance and links to job openings. The Skillsfuture programme provides a platform to access courses and training to improve employability. National Arthritis Foundation is a charitable body which raises funds to be utilised as financial subsidies for financially needy patients for treatment or to enhance employment prospects.

In addition, patient's mental well-being often suffers along with the chronic pain. Chronic pain can also bring about friction among family members as patients assume the sick role. With multiple facets of life affected, these patients may find it difficult to access help and have respite. FPs and GPs can suggest and link up the patients with available community resources. Besides the Samaritans of Singapore hotline, there are various avenues for counselling that may be helpful [Table 2]. These organisations include Silver Ribbon Singapore, which offers free basic counselling services, and Singapore Association for Mental Health (SAMH), which provides in-person counselling sessions. Other organisations may have religious roots, in which some patients may find the counselling more relatable. These include Shan You, an organisation with buddhist roots, and Calvary Community Care, which was founded by a church. Typically, churches have volunteers who provide help with counselling as well.

Table 2.

Summary of community resources.^*

Support groups
Crohn’s & Colitis Society of Singapore	info@ibd.org.sg https://ibd.org.sg/english/
Autoimmune Diseases Support Group	Join Facebook Group
Psoriasis Association of Singapore	9005 8264 PsoriasisSG@gmail.com
Knee Osteoarthritis Improvement Group	6397 7190
Work-related resources
Workforce Singapore	6883 5885 https://www.ssg-wsg.gov.sg/
Skillsfuture	https://www.myskillsfuture.gov.sg/content/portal/en/index.html
National Arthritis Foundation	6227 9726 info@naf.org.sg
Counselling services
Samaritans of Singapore	1800 221 4444
Silver Ribbon Singapore	6386 1928 (Serangoon Central) 6509 0271 (Wisma Geylang Serai) 6385 3714 (Hougang Street 51)
Singapore Association for Mental Health	1800 283 7019 (Helpline) 6255 3222
SAGE Counselling Centre (Older Persons)	63541191 reception@sagecc.org.sg
Shan You Counselling Centre	6741 9293 info@shanyou.org.sg
Calvary Community Care	6281 1866 care@calvary.sg

^*This list shows a few representative examples and is not exhaustive.

WHEN SHOULD I REFER TO A SPECIALIST?

Doctors should refer their patients to a specialist in these scenarios: (a) the patient has persistent pain that significantly impacts on function and quality of life or causes anxiety and/or depression, and has not responded to initial management; (b) the patient continues to seek medical treatment for persistent pain that cannot be explained; (c) the patient is a possible candidate for interventional treatment; (d) the patient requires high-dose opioid therapy, shows possible opioid dependence or has a moderate-to-high risk of opioid dependence based on risk screening tools; and (e) the patient needs multimodal treatment not available in a primary care setting.

TAKE-HOME MESSAGES

1. Elucidate the cause of the pain. If the chronic pain is secondary to a mechanical pathology (i.e. spinal stenosis or osteoarthritis), explore if surgical options have been discussed.

2. Chronic non-cancer pain often has many facets. Considering the biopsychosocial aspects of the presentation can help to identify various contributing factors and provide effective treatment.

3. 4 'P's management: Pharmacological, Physical, Psychological and Procedural. There are numerous pharmacological treatments available, and these medications can be directed based on the type of pain and the underlying contributing disease.

4. Opioid therapy is often associated with adverse effects, misuse and dependence. Utilising risk screening tools and regular monitoring can help to reduce these problems and allow for early detection and intervention.

5. Patients should be empowered through patient education and understand the various treatments for better management of chronic pain.

6. Consider other non-pharmacological treatments as a multimodal approach, especially for patients who may not be suitable for surgical treatment and aggressive pharmacological treatment due to its adverse effects.

7. Consider psychosocial implications of chronic pain and offer management options for more holistic care.

8. Timely referral to a tertiary centre should be considered and made in the above-mentioned situations.

Closing Vignette

You found out that Mrs Yeo had mild depression brought on by the chronic back pain and the resultant functional limitations. She had previously been trialled on paracetamol and short courses of nonsteroidal anti-inflammatory drugs. You started her on combination therapy, including duloxetine, and explained to her about the biopsychosocial nature of chronic pain. On review, Mrs Yeo's pain had improved, although it was still causing functional limitations. You referred her to a pain specialist for consideration of procedural treatment, as well as a physiotherapist and psychologist. After 3 months, Mrs Yeo reported that she was feeling much better and was now able to better ambulate in the community.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

SMC CATEGORY 3B CME PROGRAMME

Online Quiz: https://www.sma.org.sg/cme-programme

Deadline for submission: 6 pm, 17 March 2023

Question	True	False
1. Chronic non-cancer pain is a disease of the aged and is untreatable.
2. Pharmacological treatment is the best modality.
3. Chronic non-cancer pain is best managed with multiple modalities.
4. It is not useful to evaluate the biopsychosocial aspects of chronic pain.
5. Patients with mechanical causes of pain should consider surgical options.
6. Opioid therapy can be a safe and effective adjunct if used appropriately.
7. Indications for opioid therapy should be clearly documented.
8. Patients who are on long-term opioid therapy should be reviewed regularly for adverse effects and suggestion of misuse or abuse.
9. Opioid therapy cannot be initiated in primary care setting.
10. Only single analgesia agent can be used at any one time.
11. Physiotherapy can be an effective treatment for chronic pain.
12. Physiotherapy can be individualised, effective and made sustainable according to patients’ preferences.
13. Patient education helps to empower patients in self-management of chronic pain.
14. Patients with persistent pain despite initial management should be referred to tertiary pain specialist centres.
15. Associated psychological comorbidities should be evaluated and managed appropriately.
16. Interventional treatments can be effective in treating chronic pain.
17. Pharmacological agents with poor pain relief response should be continued if there are no adverse effects.
18. Opioids are often the first pharmacological agents to be initiated.
19. Family physicians can provide holistic management by considering the psychosocial implications of chronic pain.
20. Family physicians can value-add by linking patients up with appropriate community and/or social services.