Managing chronic pain in older people

Key points

• The commonest sites of pain experienced by older people are the back, leg (knee or hip) and other joints.

• Patient report is the most accurate and reliable evidence of pain experience. Choice of pain assessment tools should take account of patients' cognition function.

• Physiological changes with ageing increase older people's sensitivity to analgesics.

• Despite a higher incidence of adverse effects in older people, analgesics can still be safe and effective when comorbidities and concomitant medications are carefully reviewed.

• Paracetamol is recommended as the first-line pharmacological treatment, whereas NSAIDS should be used with caution, and given for the shortest course at the lowest effective dose for older people.

Assessment of pain

The aim of pain assessment is to identify the characteristics and impact of pain by appreciating the biopsychosocial model of pain, so as to inform the planning of individualised interventions via a multidisciplinary approach.

Patient report is regarded as the most accurate and reliable evidence of the pain experience. Simple questions and tools can be used to assess patients with mild to cognitive impairment. Supplementary information from caregivers should also be included.⁴

Pain history could be obtained by the OPQRST approach: onset, provoking factors, quality, radiation/region, severity and temporal. Evaluation should include the impact of pain on functional and psychosocial aspects, eg basic and instrumental activities of daily living, sleep, appetite, mood, cognition, attitudes and beliefs, interpersonal relationships, and social activities. Relevant comorbidities and use of medications should be reviewed. The outcomes and side effects of any currently or previously used medications should be addressed. Any drug–drug and drug–disease interactions should be assessed.^4,6,7

Various pain scales are available for use in older people, including those with mild to moderate cognitive impairment. These include the numeric rating scale (NRS), verbal descriptor scale (VDS), pain thermometers and face pain scales.^4,5 For those with severe dementia or who are non-communicable, pain assessment by means of direct observation of any pain behaviours (eg facial expressions, vocalisations, body movements, changes in interpersonal interactions and activities, changes in mental status) or history taking from caregivers should be attempted.⁴

Physical examination should focus on the musculoskeletal and neurological systems. Any signs of arthritis, weakness and sensory changes should be identified.^4,7 The patient's degree of frailty should also be taken into account.⁷ Appropriate blood tests and imaging should be followed.⁷

Treatment of chronic pain

When considering pharmacological management for older people experiencing pain, the following principles should be adopted. Due to older people's increased sensitivity to drugs, analgesics at lower doses may be required. Nonetheless, a higher incidence of side effects does not justify failure to treat. When older people's comorbidities and concomitant medications are carefully reviewed, analgesics can still be safe and effective. Attention should be given to the timing of medication administration. For example, medications with a rapid onset of action are suitable to treat episodic pain, whereas modified-release formulations are required for continuous pain. The route of medication administration should always be considered. Apart from the oral route, which is convenient and the least invasive, topical preparations may also have favourable outcomes. The rule of ‘start low, go slow’ should be followed, and combination therapy may have synergistic effects with fewer side effects than a single drug at higher dose.^3,9

Paracetamol is recommended as the first-line pharmacological treatment, particularly in musculoskeletal pain, due to its effectiveness and good safety profile.⁶ However, hepatotoxicity is a concern if patients are exposed to prolonged use of the maximum recommended doses or are underweight. In general, patients should not exceed the recommended daily dose of 4 g / 24 h of paracetamol.³

According to National Institute for Health and Care Excellence (NICE) recommendations, oral non-steroidal anti-inflammatory drugs (NSAIDs) or selective COX-2 inhibitors may be considered when paracetamol or topical NSAIDs provide insufficient pain relief for patients with osteoarthritis.⁸ However, due to the side effects, in particular gastrointestinal, renal and cardiovascular adverse effects, and contraindications in older people, NSAIDs should be avoided in managing chronic pain in older people.⁹ If the benefits of using NSAIDs outweigh the risks, the shortest course at the lowest effective dose with regular reviews can be considered.^3,9 When higher gastrointestinal risks are expected, a proton pump inhibitor (PPI) or misoprostol should be co-administered.³

Opioids should be considered for use in patients with moderate to severe pain, or functional impairment and compromised quality of life as a result of pain.⁶ Potential side effects of opioids in older people include constipation, excessive sedation, delirium, falls and fractures.⁹ Efficacy and tolerability must be regularly reviewed.^3,9 Examples of opioids include tramadol, morphine, oxycodone, fentanyl, buprenorphine, hydromorphone and methadone. Owing to the unusual pharmacokinetics of methadone, its prescription should be restricted to those with expert experience.^3,6

Adjuvant analgesics are recommended for managing older people with neuropathic pain.^5,6,9 Antidepressants such as tricyclic antidepressants and selective serotonin norepinephrine reuptake inhibitors may offer beneficial effects.⁹ However, a higher risk of adverse effects, like anticholinergic effects and cognitive impairment, in older people using tertiary tricyclic antidepressants may limit their use.⁶ Anti-epileptics should also be used with caution due to potential side effects on the central nervous system.⁹ Therapy should be initiated at the lowest possible dose, followed by slow escalation based on response and side effects. Take gabapentin as an example: the onset of efficacy may take up to 2–3 weeks.⁶

Topical therapies are reasonable alternatives. There have been evolving guidelines recommending topical NSAIDs as first-line therapy in the treatment of osteoarthritis.¹⁰ For localised neuropathic pain, topical lidocaine may offer a second-line treatment.^6,9 Nonetheless, absorption of transdermal drugs may vary in frail older people with significant subcutaneous tissue loss, thereby creating difficulties in predicting drug efficacy.¹¹

As mentioned, pain is more than a physical sensation. The biopsychosocial model of pain reinforces the influence of psychological factors on patients' response and coping strategies. Psychological interventions like cognitive behavioural therapy (CBT) may be effective as an adjunct to pharmacological therapies.³ Physical activity is important in managing chronic pain in older people; it can help to maintain their independence and quality of life. Reviews of randomised controlled trials recommend programmes that involve strengthening, endurance and flexibility for patients regardless of age.^3,9