“Pain is an unpleasant sensory and emotional experience accompanied by actual or potential tissue damage, or described in terms of such damage.” International Association for the Study of Pain
CONSISTENT with other high income countries, Australia has an ageing population. An older Australian is defined as being 65 years old or over. From 1996 to 2016, the proportion of people aged 65 years and over increased from 12% to 15.3 %. By 2056, it is projected there will be 8.7 million older Australians (22% of the population).
Our ageing population reflects both declining fertility as well as increased life expectancy. Factors contributing to longer living are advances in medical treatment and public health, rising standards of living and better education around lifestyle and nutrition.
Pain is a common presenting problem for an older patient in primary health care. Older patients are more likely to seek treatment for both acute pain and chronic pain issues — chronic pain being persistent or recurrent pain lasting more than 3 months.
More worryingly, older patients may fail to report pain. Pain may be perceived as a normal part of ageing, which is incorrect. A more appropriate assumption is that pain is more common in older patients because of increased prevalence of disease, disease treatment and organ dysfunction.
Chronic pain may be either nociceptive or neuropathic. Both nociceptive pain (the more common pain, arising from actual or threatened tissue damage due to stimulation of sensory nerve endings called nociceptors) and neuropathic pain (pain arising from a lesion or disease of the nervous system) are more common in older patients and may coexist.
One of the most common causes of nociceptive pain in older patients is musculoskeletal problems. Increased musculoskeletal-related pain presentations reflect chronological tissue wear and tear as well as disease processes of bones, joints and muscles. Osteoarthritis has increasing prevalence in a sedentary and overweight population. In the United States, osteoarthritis affects at least 50% of the elderly population and chronic pain is the most prominent symptom. Painful tendinopathies are more common in patients with joint dysfunction, antalgic gait and propensity to falls.
Other types of nociceptive pain relate to advanced chronic diseases, which are frequently accompanied by pain: congestive heart failure, end-stage renal disease and chronic obstructive pulmonary disease.
Neuropathic disorders are more common in older patients. Painful peripheral neuropathy afflicts more than 60% of older patients with diabetes. The dramatic increase in the prevalence of type 2 diabetes is again a significant public health issue in an older, sedentary and overweight population. Post-herpetic neuralgia (PHN) is more common in the very elderly (greater than 75 years), and age of onset of an acute herpes zoster rash determines the likelihood of PHN. Ten per cent of patients with shingles develop PHN, and this percentage rises to over 30% in patients over the age of 80 years.
Chronic post-surgical pain is also more prevalent in older patients. Operations performed more commonly in older patients and at higher risk of chronic post-surgical pain include thoracotomies, mastectomies, and hip and knee arthroplasties. Chronic post-surgical pain frequently has a neuropathic component and is a diagnosis of exclusion, as all other causes of pain (infection, recurring malignancy) and pre-existing pain problems need to be ruled out.
Finally, cancer and cancer treatments are painful and increasingly prevalent in older patients. Pain may be nociceptive (such as a pathological vertebral fracture) or neuropathic (an accompanying nerve root compression) or both. Chemotherapy-induced painful peripheral neuropathy is a common impediment to effective treatment. Cancer survivors more commonly describe chronic pain than cohort groups with no cancer history.
Which older patients are at risk of chronic pain?
By definition, pain is subjective and has both sensory and emotional qualities. Chronic pain has affective (emotional responses to pain), cognitive (attitudes and beliefs about pain), behavioural (in response to pain) and sensory components.
Why two patients describe significantly different pain experiences, yet have the same disease, pathological process or the same changes demonstrated on imaging, remains unclear. The probability of chronic pain developing is influenced by genetic and physiological factors and how these interact with accumulated psychological and social experiences of pain. Risk factors for chronic pain include advancing age, female sex, lower socio-economic and educational levels, obesity, smoking, history of trauma, previous manual employment and mood disorder.
How do we assess pain in older patients?
A comprehensive patient assessment incorporates a targeted pain history, grading pain intensity, pain-related distress and functional impairment. Pain is associated with significant disability — physical, social and vocational. Reid and colleagues recommend a comprehensive geriatric assessment in all older patients with chronic pain. Identification of targets for intervention other than pain are an important aspect of the assessment.
How do we treat pain in older patients?
Management of pain in the older patient requires a multidisciplinary and multimodal approach, including both drug and non-drug therapy.
Cognitive behavioural therapy:
Chronic pain is maladaptive and does not serve the protective role of acute pain. Chronic pain is complex and subjective, modified by mood, previous experience, unhelpful thoughts, feelings and behaviour. Cognitive behavioural therapy techniques improve patients’ distress, disability and self-efficacy in managing chronic pain. Addressing and modifying an individual’s beliefs, attitudes and behaviour enhance patients’ control over the experience of pain.
Lifestyle optimisation should be addressed. Patients are more likely to consider strategies such as cessation of smoking, weight loss and reduction of alcohol intake if encouraged to do so by the treating doctor – as opposed to family and friends. Self-management programs merge physical, psychological and social dimensions. Obesity is the most important modifiable risk factor in osteoarthritis, so weight loss is essential.
Physical activity is the cornerstone to successful management of chronic pain in the elderly.
Exercise interventions for older adults with chronic pain are evidence-based, underutilised and should be a core component of any treatment plan.
Activity correlates with physical conditioning and attenuates pain. Physiotherapy incorporates muscle strengthening, balance training as well as aerobic exercise. A graded approach to an increased daily level of activity is frequently required with both home exercises and regular review.
Harm minimisation is paramount. Careful consideration should be given to the class of analgesic, route of administration and duration of prescription. Decreased physiological reserve associated with organ dysfunction increases the likelihood of adverse effects with analgesics. Polypharmacy is commonplace in the Webster packs of older patients, and drug–drug interactions are eminently avoidable.
Caution is recommended in ascribing to the World Health Organization ladder of oral analgesia for non-cancer pain management in older patients.
Paracetamol is a centrally acting analgesic that has long been advocated as first-line treatment for mild and moderate pain. It is metabolised by the liver and renally excreted. Caution should be exercised in liver or renal impairment and states of malnourishment.
More recent guidelines suggest that dose adjustment in the elderly is prudent, and Rastogi and Meek recommend limiting doses to 2000 mg/day in older patients. Fifty per cent of hepatic dysfunction in the elderly is a consequence of inadvertent paracetamol toxicity. Subsequently, the United States Food and Drug Administration has lowered the dose in compounded tablets to no more than 325 mg of paracetamol.
Long term administration of non-steroidal anti-inflammatory drugs (NSAIDs) is strongly discouraged. Approximately 25% of inadvertent drug reactions leading to hospital admissions in the elderly are attributed to prolonged use of NSAIDs. The range of these effects is extensive: hypertension, oedema, cardiac events, renal dysfunction, and gastrointestinal bleeds. Short term use of NSAIDs for older patients with normal renal function may well be appropriate to manage pain flares in chronic diseases such as rheumatoid arthritis and osteoarthritis. NSAIDs are opioid-sparing when administered for post-operative pain.
Topical NSAIDs are useful for focal nociceptive pain such as inflammatory joint disease. Systemic absorption is minimal, with little risk of adverse effects.
Opioids may be considered when an older patient’s pain has not responded to other treatments or when major functional impairment exists despite treatment.
Prescribing of opioid analgesia is accompanied by the preamble “start low and go slow”. Universal precautions should be adhered to in prescribing opioids in the elderly, as for any other patient group. The Opioid Risk Tool is a useful means of identifying patients who are at risk of misusing opioids and any suggestion of diversion mandates immediate discontinuation. Opioid prescribing requires an agreed opioid contract, regular patient review and an understanding that opioids will be weaned and ceased if there is no functional improvement.
Suggested starting doses of opioids should be lower in older patients. The brain sensitivity to opioids increases by about 50% in older individuals. The most common adverse effects in older patients are nausea, cognitive dysfunction and constipation. Prophylactic management of constipation should be commenced whenever opioids are prescribed.
All opioids are equianalgesic but some are safer than others, particularly in the presence of renal dysfunction. Buprenorphine is considered to be a safer choice of opioid in the elderly; it has a ceiling effect for opioid-induced respiratory depression but not for analgesia. Two-thirds of the drug are excreted unchanged, mainly in the faeces, and it is safe for use in hepatic and renal dysfunction. The risk of respiratory depression is low, provided concurrent sedative medications are not given.
Tapentadol, a dual action opioid, is considered safe for use in the elderly. Again, it has less propensity to sedation or respiratory depression due to its primary mechanism of action being noradrenaline reuptake inhibition. Data from chronic pain settings show reduced rates of gastrointestinal side effects leading to reduced rates of discontinuation. In contrast to tramadol it has no relevant serotonin reuptake inhibition and no active metabolites.
Pharmacotherapy for neuropathic pain is primarily with antidepressants or anticonvulsants or a combination of these two classes. Finnerup and colleagues conclude that overall, neuopathic pain is only modestly responsive to medications used to treat it. Adverse effects are significant in the elderly and are dose-related, mandating careful dose titration. There is Grade 1 evidence for low dose tricyclic antidepressants and serotonin noradrenaline reuptake inhibitors. Nortriptyline has fewer side effects (constipation, urinary retention) than amitriptyline and is more suitable for the older patient. Duloxetine has the advantage of being titratable for mood optimisation. There is Grade 1 evidence for gabapentins, including both pregabalin and gabapentin. The number needed to harm is significantly higher for gabapentin at 26, making it a safer but more expensive choice in the older patient.
Lignocaine patches may be a suitable choice for focal neuropathic pain such as PHN. Systemic absorption is minimal with little risk of adverse effects. Again, there is a significant financial consideration with this drug.
Managing pain with interventional treatment options may reduce the number and doses of analgesics required.
Interventions for pain secondary to osteoarthritis include radiofrequency denervations for facet joint arthropathy, commonly cervical and lumbar. Thermal radiofrequency neurotomies of genicular nerves may benefit patients delaying joint arthroplasty or to treat persistent knee pain after arthroplasty.
Neuropathic pain is responsive to neuromodulation. Clinical indications for a trial of spinal cord stimulation include complex regional pain syndrome, lower limb neuropathic pain after spinal fusion surgery or peripheral nerve damage.
Interventional treatments should be performed by a pain specialist in a suitable environment, with expertise in this area.
Managing pain in the older patient can be challenging but is also rewarding. Older patients rate pain and good health highly as determinants of quality of life and are grateful when improvements can be made.
Dr Jane Standen is a consultant anaesthetist at the Royal North Shore Hospital in Sydney and an interventional pain specialist at Sydney Pain Specialists. She has expertise in the management of both early onset and persistent pain. Her areas of interest include complex regional pain syndrome, neuropathic pain and pain management in the elderly.
The statements or opinions expressed in this article reflect the views of the authors and do not represent the official policy of the AMA, the MJA or MJA InSight unless that is so stated.
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