Pain is a common complaint among elderly persons. For ambulatory care visits, pain-related problems are more common than any other complaint. The intensity of pain often correlates with the severity of injury and indicates urgency for treatment. Unrelieved pain, pain that persists, or pain out of proportion to tissue damage, over time, often results in substantial disability and psychological distress.

Epidemiology studies of pain in general populations have suffered from the lack of standard definitions for what might be considered “significant” pain. Nonetheless, studies have suggested that the prevalence of pain in community-dwelling older persons may be as high as 25% to 56%. Sources of pain also vary from study to study. Prevalence of back pain has been reported from 21% to 49.5%; joint pain 20.5% to 71%; and headache 1.2% to 50% in persons older than 65 years. In general, the most common causes of pain in elderly persons are probably related to musculoskeletal disorders such as back pain and arthritis. Neuralgia is common, stemming from diseases such as diabetes, herpes zoster, and trauma such as surgery, amputation, and other nerve injuries. Nighttime leg pain (e.g., cramps and restless legs) is also common, as is claudication. Cancer, although not as common as arthritis, is a cause of severe pain. The distress of cancer pain has brought attention to the obligation that clinicians have to provide effective pain management especially near the end of life. Pain is also common in nursing homes. Between 45% and 80% of nursing home residents may have substantial pain. Many have multiple pain complaints and multiple potential sources of pain. Pain is associated with a number of negative outcomes in elderly people. Depression, decreased socialization, sleep disturbance, falls, adverse drug events, slow rehabilitation, and increased health care utilization and costs have all been associated with either the presence of pain or its treatment in older people. Older patients rely heavily on family and other caregivers near the end of life. For these patients and their caregivers, pain can be especially distressing. Caregiver strain and caregiver attitudes can have substantial impact on pain.

The approach to pain management is different in elderly versus younger persons. Older persons may underreport pain. They often present with concurrent illnesses and multiple problems, making pain evaluation and treatment more difficult. Elderly persons have a higher incidence of side effects to medications and higher potential for complications and adverse events related to many treatment procedures. Despite these challenges, pain can be effectively managed in most elderly patients. Moreover, clinicians have an ethical and moral obligation to prevent needless suffering and provide effective pain relief, especially for those near the end of life.

The effect of aging on pain perception has been a topic of interest for many years. Elderly persons often present with altered presentation of common diseases. For example, older persons have been observed to present with apparently painless myocardial infarction and painless intra-abdominal catastrophes. The extent to which these observations are attributable to age-related changes in pain perception remains uncertain. Anatomical studies, as summarized in Table 30-1, have observed some age-related changes in the nervous system that might alter pain perception. Some of these findings include decreased numbers of various pain receptors in the skin and other organs, altered nerve conduction, and some central nervous system changes that may affect sensory processing. Most of these studies were based on cross-sectional studies of animal and postmortem specimens, for which little or no data were actually available, or correlated with the premortem pain experiences.

Likewise, a large number of physiologic studies of pain perception also exist. These studies typically use a heat probe, electrical stimulation, or other methods to induce pain in volunteers in an effort to identify a pain threshold or pain tolerance level. These studies have shown mixed results, some showing increased, some showing decreased, and some showing no change in pain perception with aging in normal volunteers. Moreover, it has been difficult to conduct a formal meta-analysis using all of these studies because of flaws in many of these studies concerning sampling errors and methodological differences. In the final analysis, most investigators have concluded that actual age-associated changes in pain perception are subtle and probably not clinically significant.

On the other hand, elderly people often present with concurrent illness and sensory impairments that may mask pain complaints. Cognitive impairment, sensory neuropathies, and visual and hearing impairment, each may make communication of pain complaints more difficult and thus appear to be a perceptual problem. Elderly patients may be more stoic; they may expect pain with aging and fear diagnostic tests, other interventions, or the meaning of pain. These issues can make pain assessment and measurement much more difficult in older people.

Pain is quite variable in description, character, and intensity among individuals. For the purpose of understanding, predicting, and treating pain, a variety of classification schemes have been used. For diagnostic purposes, it may be helpful to categorize pain as acute or persistent. The old term “chronic pain” is now considered obsolete, and the newer term “persistent” is used to reduce the common biases and negative stereotypes associated with the label “chronic pain patients” in the past. For treatment purposes, it may be more helpful to categorize pain as nociceptive versus neuropathic.

Acute Versus Persistent Pain

Acute pain is defined by a distinct onset, obvious cause, and short duration. Trauma, burns, infarction, and inflammation are examples of pathological processes that result in acute pain. Acute pain is often associated with autonomic nervous system signs, including tachycardia, diaphoresis, or elevation in blood pressure. The presence of acute pain usually indicates an acute injury or acute disease, and the intensity of acute pain often indicates the severity of injury or disease. Thus, acute pain should trigger an urgent search for an underlying cause that might be life-threatening or require immediate intervention. The effective management of acute pain is important to facilitate diagnostic tests. Preoperative pain management of acute pain makes anesthesia easier and postoperative pain control better. In some cases, management of acute pain can help prevent development of chronic pain syndromes.

Chronic pain is usually defined by its persistence beyond an expected time frame for healing, usually longer than 3 months. Intensity of chronic pain is often out of proportion to the observed pathology and associated with prolonged functional impairment, both physical and psychological. Autonomic signs are often absent. Underlying causes of chronic pain are often associated with chronic disease and are less remedial.

Chronic pain is often more difficult to manage in older patients because the underlying cause is less curable and many treatment strategies are short lived, difficult to maintain, or associated with long-term side effects. Chronic pain usually requires a multidimensional approach to treatment, including use of both analgesic drug and nondrug strategies with attention to sensory, emotional, and behavioral components of the pain experience.

Nociceptive Versus Neuropathic Pain

For treatment purposes, it may be helpful to identify the underlying mechanism of pain perception. Treatment aimed at specific pathophysiologic pain mechanisms may be more effective. Pain problems that result largely from stimulation of pain receptors are called nociceptive pain. Nociceptive pain may arise from tissue injury, inflammation, or mechanical deformation. Examples include trauma, burns, infection, arthritis, ischemia, and tissue distortion. Pain from nociception usually responds well to common analgesic medications.

Neuropathic pain results from pathophysiologic processes that arise in the peripheral or central nervous system. Examples include diabetic neuralgia, postherpetic neuralgia, and post-traumatic neuralgia (postamputation or “phantom limb” pain). In contrast to nociceptive pain, neuropathic pain syndromes are often persistent and difficult to treat. They may, however, respond to nonconventional analgesic medications such as tricyclic antidepressants and anticonvulsant drugs. For these syndromes, it is important to recognize them early and to begin treatment with adjuvant analgesic strategies before development of long-term complications of persistent pain including physical and psychological disability.

There are other physiological mechanisms of pain, including mixed nociceptive and neuropathic syndromes and pain syndromes of unknown mechanisms. Treatment for these is more problematic and often unpredictable. Examples include recurrent headaches and some vasculitic syndromes. Finally, psychologically based pain syndromes are those with psychological factors that play a major role in the pain experience. Examples include somatoform disorders and conversion reactions. These patients may benefit from specific psychiatric intervention, as traditional pain strategies are often ineffective.

Pain assessment is the most important part of pain management. Any pain complaint that has an impact on physical function or quality of life should be recognized as a significant problem. Unfortunately, there are no objective biological markers of pain. The most accurate and reliable evidence for the existence and intensity of pain is the patient’s description.

Pain History and Physical Examination

Assessment of pain should begin with a thorough history and physical examination to help establish a diagnosis of underlying disease and form a baseline description of pain experiences. The history should include questions to elicit: when the pain started, what events or illnesses coincided with the onset, where does it hurt (location), how does it feel (character), what are the aggravating and relieving influences, and what treatments have been tried. Past medical and surgical history is important to identify coexisting disease and previous experience with pain and analgesic use. The review of systems should probably focus on the musculoskeletal and nervous system because of the frequency of which these pain problems often occur in older persons. Any history of trauma should be thoroughly investigated because falls, occult fractures, and other injuries are common in this age group. Care must be taken to avoid attributing acute pain to preexisting conditions and recognize that chronic pain may fluctuate with time. Injuries from minor trauma and acute disease such as gout or calcium pyrophosphate crystal arthropathy can be easily overlooked. Finally, many older persons do not use the word “pain,” but may refer to their problems as “hurting,” “aching,” or other descriptions. It is important to probe for and identify pain in the patient’s own words so that references for subsequent follow-up evaluations are clearly established.

A physical examination should confirm any suspicions suggested by the history. Because of the frequency with which problems are often identified, the physical examination should probably concentrate on the musculoskeletal and nervous systems. Tender points of inflammation, muscle spasm, and trigger points should be palpated. Observation of abnormal posture, gait impairment, and limitations in range of motion may trigger a need for physical therapy and rehabilitation. Evidence of kyphosis, scoliosis, and abnormal joint alignments should be identified. A systematic neurological examination is also important to identify potential sources of neuropathic pain. Focal muscle weakness, atrophy, abnormal reflexes, or sensory impairments may indicate peripheral or central nervous system injury. Mottled skin in a denervated extremity, presence of a Charcot joint, orthostatic hypotension, impaired gastric emptying, or incontinence may indicate autonomic nervous system dysfunction that can imply sympathetically maintained pain or a complex regional pain syndrome.

Assessment of functional status is essential to identify self-care deficits and formulate treatment plans that maximize independence and quality of life. Functional status can also represent an important outcome measure of overall pain management. Functional status can be evaluated from information taken from the history and physical examination, as well as the use of one or several functional status scales validated in elderly people.

A brief psychological and social evaluation is also important. Depression, anxiety, social isolation, and disengagement are all common in patients with persistent pain. There is clearly a significant association between persistent pain and depression, even when controlling for overall health and functional status. Therefore, assessment should, at least, include a screen for depression. Psychological evaluation should also include consideration of anxiety and coping skills. Anxiety is common among patients with acute and persistent pain, which requires extra time and frequent reassurance from health care providers. Persistent pain often requires effective coping skills for anxiety and other emotional feelings that can be learned. For those with significant psychiatric symptoms, referral for formal psychiatric evaluation and management may be required. In these patients, cognitive-behavioral therapy, specific counseling, supportive group therapy, biofeedback, or some psychoactive medications may be necessary for developing and maintaining effective coping strategies as well as management of major psychiatric complications. Social networks should also be explored for availability and involvement of family and other caregivers. Family and informal caregivers are often involved and can have a substantial impact on overall pain management. Evaluation of caregivers is necessary when complicated or high-tech pain management strategies are contemplated, such as continuous analgesic infusions. Some pain management strategies can place substantial demands on caregivers, resulting in substantial caregiver stress. Needs for frequent transportation, administration of pain treatments, and technical training may result in substantial stress for nonprofessional caregivers, which can result in work absence and emotional and physical illness.

Pain Assessment Scales

A variety of pain scales are available to help categorize and quantify the magnitude of pain complaints. Results of these scales are helpful in documentation initially and periodically to maximize treatment outcomes. Results can be recorded in flow chart or graph, making it easy to identify stability or changes in pain over time. Since there are no “gold standards,” the validity of pain scales relies largely on face value, correlation with other known scales (concurrent validity), correlation with pain-related constructs (convergence), and experience in many populations over several years.

Pain scales can be grouped into multi- and unidimensional scales. In general, multidimensional scales with multiple items often provide more stable measurement and evaluation of pain in several domains. Table 30-2 summarizes some of the multidimensional scales available. For example, the Brief Pain Inventory has been shown to capture pain in terms of intensity, location, and interference with activities. At the same time, multidimensional scales such as the McGill Pain Questionnaire are often long and time consuming and can be difficult to score at the bedside, making them difficult to use in a busy clinical setting. Table 30-1 provides a description of several available multidimensional scales for pain. For the last 10 years, data have been accumulating on some of these scales in older persons.

One example of a behavioral scale is the Hurley Discomfort Scale. This instrument was developed for the assessment of discomfort in patients with profound dementia. The scale consists of nine items scored by a trained examiner after observation the behavior of a noncommunicative patient. Behavioral observations such as breathing, vocalization, facial expression, body language, and restlessness are scored on Likert scales. Testing of the scale has demonstrated reasonable reliability and stability over time. The scale requires some skill and experience to administer, which may be problematic for some clinical settings.

Unidimensional scales consist of a single item that usually relates to pain intensity alone. These scales are usually easy to administer and require little time or training to produce reasonably valid and reliable results. They have found widespread use in many clinical settings to monitor treatment effects and for quality assurance indicators. Table 30-3 describes some unidimensional scales that are commonly used, but a large number of variants that have similar characteristics and produce similar results are also available. Unidimensional pain scales often require framing the pain question appropriately for maximum reliability. Subjects should be asked about pain in the present tense (here and now). For example, the interviewer should frame the question: “How much pain are you having right now?” Alternatively, the interviewer can ask: “How much pain have you had over the last week?” or “On average, how much pain have you had in the last month?” The latter questions require accurate memory and integration of pain experiences over time, which may be more difficult for some older patients. Recent studies in those with cognitive impairment have shown that pain reports requiring recall are influenced by pain at the moment. Thus, it may be more useful to use unidimensional scales in this population to assess pain at the moment, much the way vital signs are used.