Introduction

Pain is a percept defined as an unpleasant sensory and emotional experience associated with actual or potential tissue damage or described in terms of such damage.1 Most health conditions associated with ageing carry a substantial burden of pain. Pain is always subjective as there is no way to validate objectively a patient’s pain report. Every day acute pain occurs as an early response to a strong mechanical, thermal or chemical noxious stimulus such as experienced after an injury or surgery, where it may be immediate or delayed by hours or with infection that develops over hours and persists for a few days. Acute pain demands attention and an early response in order to obtain pain relief and protection from further tissue damage. Acute pain is easily recognized by clinicians, who are well trained to seek a cause so that treatment can be implemented without unnecessary delay. Acute pain affects about 5% of older people at any point in time.2 Often self-limiting, acute pain usually resolves either spontaneously or with specific treatment often directed at the cause of the pain such as when immobilizing a fracture. The older patient presenting in acute pain should not be taken lightly.

In a proportion of cases, pain does not resolve spontaneously, with the patient progressing through a subacute phase to chronic pain. At this stage, pain no longer serves a protective role and is associated with social, functional and psychological consequences. Chronic pain is best defined as pain persisting beyond the period of normal recovery.3 By consensus, this has been taken to be 3 months if pain has an ongoing cause. When chronic pain has accompanying physical, psychological and social consequences, multidisciplinary management strategies are required. Common sense dictates that in this situation the source of chronic pain should be understood and that investigations and treatments previously used but found to be ineffective be documented to ensure nothing remediable has been missed. There is, however, still a tendency to ‘medicalize’ the patient with chronic pain at the time of presentation to a new treatment team, with further investigations and repeated treatments, often with an over-emphasis on pharmacological and anaesthetic approaches. It becomes the managing physician’s role in this context to recognize that curative approaches are no longer feasible or acceptable to the patient and that it is time for a symptom management approach to be adopted, aiming to reduce pain to tolerable levels, enhance the individual’s coping strategies and minimize any pain-related handicap. This chapter summarizes pertinent data in this field and presents a model for the assessment and management of chronic pain in older people.

Pain and Ageing

Overall, the prevalence of persistent pain increases with age and peaks between 45 and 65 years of age in males and between 65 and 75 years in females.4 Prevalence estimates of persistent pain in older adults range between 25 and 50%. Among nursing home patients, the reported prevalence ranges are generally wider, being reported to be between 27 and 83% in one study.5 This wide range, especially in residential care settings, indicates the difficulty in addressing a subjective experience in a population with a high prevalence of comorbidities, particularly those associated with cognitive and communication difficulties. This has been the focus of some published management guidelines.6 There are also methodological differences that partially explain these variations.5, 7 Thus, high prevalence studies often use surrogate measures such as carer opinion and analgesic use to support the contention that the person is in pain. In community samples, the variation may be the result of using biased samples, different time windows for pain (e.g. pain in the last week or month versus all-of-life pain) or summing of pain experienced at different body sites. However, most of the variability is more convincingly explained by using different criteria for determining the effect of pain in interfering with desired functional outcomes for the individual.

Most of this reported pain prevalence, however, is dictated by the high prevalence and persistence of musculoskeletal disease, especially degenerative joint disease in the spine, limbs, hands and feet. This is an example of somatic nociceptive pain. Other pain states are also important to older people although they may have less impact on prevalence studies because of their relatively limited duration, perhaps 1 year or less, compared with degenerative disease which lasts for decades. Visceral pain is characterized by poor localization and may be associated with strong emotional and autonomic responses. The principles for management of chronic visceral pain are the same as for somatic pain, with the rare exception of surgical lesioning of the posterior instead of the lateral columns of the spinal cord if pain is intractable to all treatments. Many of these conditions are described in detail in other chapters. A summary classification of clinical pain states into nociceptive, neuropathic, mixed and other, together with some examples that affect older people, is given in Table 69.1.

Table 69.1 Classification of chronic non-cancer pain.

Type of pain	Definition	Examples
Nociceptive pain	Pain derived from stimulation of pain receptors. It may arise from trauma and mechanical causes, inflammation, degenerative and other pathologies	Low back disorders (vertebral compression fractures, facet arthropathies, spondylosis)
		Rheumatoid and other inflammatory arthritides
		Visceral pain, e.g. chronic pancreatitis, cholecystitis, prostatitis, recurrent myocardial ischaemia
Neuropathic pain	Damage to the peripheral and/or central nervous system	Post-stroke pain syndromes, diabetic neuropathy, post-herpetic neuralgia, carpal tunnel syndrome, trigeminal neuralgia, radiculopathy, vertebral canal stenosis, surgery
Pain related to psychological or psychiatric disorders	Psychological/psychiatric factors are judged to play a major role in the onset, severity and maintenance of pain	Pain disorder (DSM4)
Pain of uncertain pathogenesis		Recurrent headaches, fibromyalgia, irritable bowel syndrome
		Complex regional pain syndrome type 1

One of the most important pain-associated disease states of short duration in older people is cancer, as over half of cancer patients are aged 60 years or over and more than 90% experience pain with their disease. About 20% of cancer patients have pain associated with their treatment. Cancer pain can be nociceptive, neuropathic or mixed in type.

Other chronic neuropathic pain conditions that affect predominantly older people, albeit in smaller numbers, include peripheral nerve conditions such as post-herpetic neuralgia, with at least 50% of affected people aged over 70 years experiencing 1 year of pain and painful peripheral neuropathy, with diabetes as the commonest cause in 30% of cases. Neuropathy occurs in ∼50% of diabetic patients and pain is a feature in about 20% of this group. Other causes of peripheral neuropathic pain include surgery, radiculopathies and nerve compressive syndromes, including vertebral canal stenosis. Central neuropathic pain after stroke, another age-related disease, occurs in 8% of stroke-affected persons. Trigeminal neuralgia, although relatively less common, is also observed more often in older people.

The Biopsychosocial Concept of Chronic Pain

Pain is never a consequence of age alone and it is rare for it to have an entirely psychological genesis at any age. Many people cope with persistent pain and do not seek medical intervention as they perceive that the burden of treatment is greater than the burden of disease. In nearly all situations where chronic pain is a problem for the patient, there is evidence of nociceptive and/or neuropathic pathophysiology associated with maladaptive attitudes or beliefs and inappropriate behaviours operating in a potentially adverse social milieu. The current concept of chronic pain is that cognitions (appraisal of the situation and beliefs about pain and its treatment) are interposed between noxious stimulus input into the central nervous system and behavioural outcomes. Thus, an approach that targets only the pain stimulus and its nociceptive and neuropathic pathways, without taking into consideration the individual’s appraisal of the situation and the role of their environment and support structures, may lead to suboptimal outcomes.

Chronic pain is frequently associated with mood disturbance. Epidemiological data based on community samples suggest that about 10% of older people aged over 70 years have depressive symptoms or have been treated for depression.8 The prevalence of anxiety is less well defined as the instruments used to determine affective disturbance overlap on these domains. In pain clinic samples, older patients generally express less anxiety than their younger counterparts. Other mood states, which are rarely pursued during clinical assessment, include frustration, anger and demoralization. There are validated psychometric instruments that may be used to explore these other facets of mood disturbance in older people, such as the Profile of Mood States,9 but they have not been used in epidemiological studies.

There are multiple belief system constructs postulated in the psychological literature that might explain modulation of pain behaviours. The commonest approach is to consider coping strategies or their converse, catastrophic thinking, with feelings of despair, fear or helplessness. Other concepts, however, may also be relevant, such as locus of control, stoicism and fear avoidance. The relationship between pain and gender has not been clearly defined in older people, although certain conditions occur more commonly in elderly females, such as joint pain, chronic widespread pain and fibromyalgia. Chronic pain is more likely in widows living alone. The effects of ethnicity on pain expression in older people remains underexplored.

Age-Related Changes in the Nociceptive System

Pain threshold is the level of stimulus intensity (mechanical, thermal, chemical or electrical) that a subject first perceives as being noxious. Pain tolerance is the maximum amount of a noxious stimulus that a subject can bear. The trend of psychophysical studies suggests that the sum of physiological changes in older persons results in higher pain thresholds, especially to very brief noxious stimuli, but lower pain tolerance.10 This increase in threshold might suggest a compromise of the warning function of pain by shortening the time between perception of pain and the onset of tissue damage in the acute setting and under-reporting of mild pain so increasing the risk of undiagnosed disease or injury. On the other hand, decreased pain tolerance might lead to an increased vulnerability to persistent pain.

In addition, in the elderly, noxious stimuli delivered at low frequencies of around 0.2 Hz are capable of showing temporal summation, meaning that for the fifth repeated stimulus a noxious stimulus is rated to be more painful when compared with the first stimulus. This phenomenon only occurs in the young at higher frequencies, suggesting amplified or more severe pain in older people once stimulation is under way. In addition, it has also been demonstrated that after prolonged noxious stimulation endogenous pain modulation mechanisms in the older person are not activated to the same extent as in younger adults. The effect of these functional changes in experimental pain on the experience of clinical pain in older people is not yet completely understood, but will become clearer as further studies of these phenomena are undertaken.

The clinical literature is supportive of the notion that the older person feels less pain for a given level of nociceptor stimulation, but it is difficult to control for severity of disease, as attested in a largely anecdotal surgical literature in conditions as varied as analgesic requirements during surgery, fracture, peritonitis and ischaemic heart disease. There is also support for the view that severe clinical pain is less well tolerated in older people. Once an older person reports pain, they should be believed and managed accordingly. However, the converse may not be true. The absence of pain in an older person should not be interpreted as absence of pathology.

Assessment

When an older individual initially presents to a health practitioner with acute pain as a major symptom, it is appropriate for the clinician to be focused on the pathology causing the pain and then on the provision of symptomatic relief. However, when pain becomes chronic, the focus shifts to outcomes pertaining to quality of life, such as maintenance of independence and the balance between pain relief, increased function and side effects of treatments.

The ageing process is associated with multiple social, personal and health related losses. Persistent pain may be only one of the factors that modulates the wellbeing of the patient. Establishing how persistent pain affects overall quality of life is important in planning treatment. In some situations, when the patient is well known to the physician over many years, the relevance of the pain problem can be easily recognized and managed by the physician acting alone or in concert with an appropriate allied health professional, such as a physiotherapist. However, if the pain problem is complex and limited information is available to facilitate construction of a comprehensive management plan, even with or despite the input and best intentions of different therapists acting independently in the past, a multidisciplinary approach to management is to be preferred. In practice, the skills of a doctor, a psychologist and a physiotherapist, all experienced in the care of older people, are complementary and sufficient to allow for a broad multidimensional picture to be assembled on each patient. A nurse, occupational therapist and pharmacist may often contribute other perspectives to the assessment. The total time commitment in a complex patient may be several hours.

Domains of Assessment

Assessment of chronic pain in the older person is similar to that in the younger person. It is best based on self-report, either through face-to-face interview or by questionnaire. Common problems in older people making the assessment more difficult are visual, hearing and cognitive impairments. There may be overlap of symptoms of comorbid medical conditions further compounding the difficulties in pain assessment in older people. A summary of assessment domains relevant to the pain problem is shown in Table 69.2. Details on assessment tools validated for use in older people that cover most of these issues are contained in an international consensus statement (2007),11 the American Geriatrics Society Panel on Persistent Pain in Older Persons statement (2002)12 and guidelines for the assessment of pain on older people by the British Pain Society and the British Geriatric Society (2007),13 bring an additional clinical perspective to this task.

Table 69.2 Summary of assessment domains.

1. The medical aspect:

What are the pathological processes that have resulted in the present pain syndrome?

What are the patient’s comorbidities and how are these likely to influence the assessment and treatment processes?

Is the pain primarily nociceptor in origin, neuropathic, a combination of the two or unexplained?

Is specific disease management or a symptom management approach required or both? Are there features to suggest more sinister pathology (red flags)?

Is polypharmacy an issue complicating the management of the pain problem?

What factors are likely to limit compliance?

2. The functional aspect:

What functional implications are there for the patient from the pain as opposed to the pathology underlying the pain and other comorbid disease states?

3. The affective aspect:

Is the pain associated with depression, anxiety, anger or othermood disturbance?

4. The social aspect:

What impact does the pain have on social relationships and are relationships maintaining the chronic pain syndrome?

5. The cognitive aspect:

What are the patient’s beliefs about the cause, prognosis and treatment options for the pain?

How are these factors interacting with their pain?

What agreed simple measurable goals are there that will determine the success or otherwise of any intervention?

Is general cognition failure interfering with assessment, coping or medicalmanagement?

Is pain or its treatment interfering with memory and the ability to think?

The Medical/Physical Assessment

A thorough pain history should include information on the onset, duration, site, radiation, severity, character and temporal characteristics of the pain. The last includes such factors as whether the pain is intermittent, lasting for seconds to several days, paroxysmal (repetitive shocks) or continuous. Sometimes the frequency of intermittent pain is very revealing, especially if it is very brief and occurring only every few days, as this suggests that other factors contributing to the patient’s distress are more relevant to their assessment. Precipitating, aggravating and relieving factors are very helpful in determining both the site of pain and its cause. There may be multiple sites of pain which are of differing pathogenesis such as seen in patients with nociceptive pain from degenerative disease of the spine combined with radicular pain in the limb of neuropathic type. Sometimes the interaction is from two distinct pathologies such as central neuropathic pain from stroke and degenerative disease of a major joint. A pain diagram may give a better representation of the type and distribution of the various pains. There are brief screening instruments which help differentiate nociceptive pain from neuropathic pain based on the pattern and quality of pain, but none are sensitive or specific enough, or have been validated independently in older people, to allow for confident use in the clinic. Some patients will deny the presence of pain but readily accede to experiencing soreness, hurt, an ache or some other descriptor that healthcare professionals would accept as being unpleasant or painful.

The severity of the pain rarely helps differentiate the type of pain which is present but is often useful in determining the success or otherwise of interventions. It may also give an insight in the patient with a long, complex, disjointed history to ask whether the pain is better, worse or the same now as it was at the time of its onset years before, bearing in mind that memory for pain is poor and correlates better with current mood state than previous pain records. It must be recognized that severity is only one approach to measurement of pain.

Severity is best determined using a simple instrument such as a 10-point scale of pain with zero representing no pain and 10 representing the worst possible pain imaginable. Some patients do better with a more limited word descriptor scaling instrument that essentially represents mild, moderate and severe pain. Older people do less well with visual analogue and pictorial scales. The important point is that the physician should be prepared to use a variety of scales and settle on the one that is best understood by the patient. Once this has been achieved, it is relatively easy to obtain a record of pain now, pain at worst, pain at best and average pain over a chosen time frame, which is conveniently represented in the Brief Pain Inventory (BPI).

These scales focus on the sensory dimension of pain. Unpleasantness scales have never been validated in older people. The McGill Pain Questionnaire (MPQ) evaluates the sensory, affective and cognitive aspects of pain. It has been validated for use in older people. It contains a five-point severity scale, the Present Pain Intensity and a variety of descriptors in sensory, affective and evaluative domains, which are most useful in building a picture of the pain type. Examples of word descriptors include aching, burning, shooting, cruel and exhausting. The short-form MPQ, also validated in older people and which concentrates on sensory and affective domains, is simpler to use than the full instrument and is easily used in a clinical setting. The authors’ preference is for the Gracely Box Scale (GBS),14 as it combines a numerical rating scale, a verbal rating scale and anchor points directly based on psychophysical experiments matching words to the intensity of physical stimuli, although its efficacy in older people has not been formally documented and the verbal rating intervals have only been validated psychophysically in young adults. Other disease-specific instruments and non-verbal measures based on facial expression are available.

The history should also include exploration of current and previous treatments, including complementary and alternative therapies and why they may have been ineffective. For instance, too rapid introduction of a medication leading to cessation of treatment prematurely because of otherwise avoidable adverse events, inadequate amounts of medication at each dose point, inappropriate timing of medication or inadequate duration of treatment trials, poor tolerance and poor compliance often underlie the brief report that the treatment was not helpful. Past physical and invasive treatments should also be recorded with similar attention to detail to ensure they were appropriately administered. It is our experience that the medication list and schedule of use provided by a referring physician rarely matches the medications placed on the table by the patient.

The physical assessment should focus on the site and nature of the pathology, including deformity, degree of firmness or fluctuance of swellings, adherence to adjacent tissues and tenderness, in addition to posture, flexibility (active and passive range of movement) and crepitus of joints, dexterity of movements and gait and direct evidence of nervous system involvement with a focused neurological examination, especially with respect to detection of altered primary sensory perceptions. This includes the presence or absence of hypoalgesia, representing peripheral or central denervation and hyperalgesia, hyperpathia and allodynia representing a state of hypersensitivity mostly due to central sensitization at a spinal cord level. This may occur following injury to both somatic and nervous system elements. It should be remembered that this hypersensitivity is associated with enlarged receptor fields resulting in pain, both spontaneous and evoked, being experienced well beyond the limits imposed by the anatomical distribution of nerve roots, plexuses or peripheral nerves that innervate the affected body part. Autonomic activity and myofascial trigger point activity are generally attenuated in older people and therefore less prominent. Observation and recording of spontaneous movements and non-verbal pain behaviours during the physical examination are also often helpful.

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