Introduction
The population is aging, with demographic shifts resulting in a significant increase in the proportion of adults 65 years and older. The rising prevalence of many long-term conditions, of which pain is a frequent symptom, is strongly associated with advancing age. Persistent pain, which exists beyond the expected healing time, often has no identifiable physical cause and is reported by around 50% of community-dwelling older adults and up to 80% of nursing home residents. In addition to increasing age, factors associated with the development of persistent pain include sex, with women being more likely than men to report persistent pain ; low income ; and mental health conditions such as depression and anxiety. Obesity is a leading risk factor for development of the painful condition osteoarthritis, which affects as many as half of all older adults. Cancer-related pain is also prevalent in older adults, with cancer being the second leading cause of death in this population. Research indicates that advancing age is a strong risk factor for undertreatment of cancer-related pain. In contrast, acute pain, a sign of injury or disease, is often treatable or even curable.
Unrelieved persistent pain in later life has many debilitating consequences, including psychological distress, social isolation, impaired sleep quality, physical disability, and increased risk for falls, as well as loss of independence. Optimizing pain management is important, but in older adults this process can be complex. Consideration of an older patient’s functional capacity is essential when formulating a management plan. Cognitive deficits are common in later life and must be considered, especially in relation to the patient’s ability to reliably report pain. The presence of obstacles to the identification, assessment, and management of pain in older adults underscores the importance of paying extra attention when providing pain care to older patients. This chapter provides the reader with an overview of current thinking regarding the assessment and management of persistent pain in older adults and describes challenges that health care providers may encounter when delivering pain care to older patients.
Physiologic Function and Aging
Anatomic and physiologic changes are considered a normal part of the aging process. Such changes are progressive, but concomitant injury or disease can rapidly worsen the health status of older individuals. Age-related changes in both pharmacokinetics (alteration of absorption, distribution, metabolism, and excretion of drugs) and pharmacodynamics (drug-related adverse side effects) necessitate a modified approach to pain management in older patients. Renal impairment is quite common and leads to increased half-lives of medications that are excreted by the kidneys. In addition, hepatic function can decline and thereby reduce arterial hepatic blood flow and increase the elimination time for hepatically metabolized drugs. Reductions in dose strength and the frequency of analgesic dosing are necessary to decrease the risk for toxicity. Older age is also associated with a change in the volume of distribution. Total body fat increases and total body water decreases, which translates into higher peak plasma concentrations for water-soluble drugs and prolonged half-lives for lipid-soluble drugs.
Both the peripheral and central nervous systems are affected by aging. There is a reduction in β-endorphin content and γ-aminobutyric acid (GABA) synthesis in the lateral thalamus and a reduced concentration of GABA and serotonin receptors. Speed of processing nociceptive stimuli and both C- and Aδ-fiber function also decrease with age, which can lead to corresponding reductions in older adults’ ability to sense and respond to “first or initial pain.” As a result, older adults may have greater susceptibility to burns and other injuries such as lacerations because they are not as likely to sense the initial pain and do not respond (e.g., removing the hand) as quickly as younger adults.
Physiologic Function and Aging
Anatomic and physiologic changes are considered a normal part of the aging process. Such changes are progressive, but concomitant injury or disease can rapidly worsen the health status of older individuals. Age-related changes in both pharmacokinetics (alteration of absorption, distribution, metabolism, and excretion of drugs) and pharmacodynamics (drug-related adverse side effects) necessitate a modified approach to pain management in older patients. Renal impairment is quite common and leads to increased half-lives of medications that are excreted by the kidneys. In addition, hepatic function can decline and thereby reduce arterial hepatic blood flow and increase the elimination time for hepatically metabolized drugs. Reductions in dose strength and the frequency of analgesic dosing are necessary to decrease the risk for toxicity. Older age is also associated with a change in the volume of distribution. Total body fat increases and total body water decreases, which translates into higher peak plasma concentrations for water-soluble drugs and prolonged half-lives for lipid-soluble drugs.
Both the peripheral and central nervous systems are affected by aging. There is a reduction in β-endorphin content and γ-aminobutyric acid (GABA) synthesis in the lateral thalamus and a reduced concentration of GABA and serotonin receptors. Speed of processing nociceptive stimuli and both C- and Aδ-fiber function also decrease with age, which can lead to corresponding reductions in older adults’ ability to sense and respond to “first or initial pain.” As a result, older adults may have greater susceptibility to burns and other injuries such as lacerations because they are not as likely to sense the initial pain and do not respond (e.g., removing the hand) as quickly as younger adults.
Assessing Pain in Older Adults
Although accurate assessment of pain is the critical first step in the pain management process, this step can challenge even seasoned clinicians. The presence of sensory and cognitive deficits, older patients’ beliefs that pain is a natural part of the aging process, patient (or caregiver) misconceptions about the meaning of pain, and language and cultural issues can all operate as barriers to effective assessment. Barriers to assessment also occur at the provider level. For example, the belief that pain is an expected part of the aging process can lead to underassessment of pain. Inadequate provider training is likewise a commonly endorsed barrier to effective pain assessment. Furthermore, older adults typically have multiple symptoms and medical conditions, which leave health care providers little time to address pain in the context of a busy office visit. The implications of these barriers are described in subsequent sections of this chapter. Recognizing these challenges and addressing them are important first steps in the assessment and management of pain in older adults.
Older patients should be asked routinely about pain at each visit, but because many older adults will not admit to experiencing “pain,” they should also be queried about the presence of ache, discomfort, or burning sensations. The following section outlines age-appropriate assessment tools for use with both cognitively intact and cognitively impaired older adults.
Assessment Tools
A wide range of assessment tools are available for use in older adults, many of which have been well validated ( Box 34.1 ). Unidimensional pain scales (e.g., those that assess pain intensity only) are feasible for use in the context of a busy clinical encounter. Examples include the verbal pain descriptor (none, mild, moderate, or severe) and numerical rating scales (0 to 5 or 0 to 10), the Pain Thermometer, and the Faces Pain Scale, all of which have been validated for use in older populations, including individuals with mild to moderate cognitive impairment. However, it is important to remember Melzack’s famous quote: “To describe pain solely in terms of intensity is like specifying the visual world only in terms of light flux, without regard to pattern, color, texture and the many other dimensions of the visual experience.” Using instruments that capture the multidimensional experience of pain, including its impact on function, is therefore strongly encouraged. In terms of multidimensional measures, the Brief Pain Inventory and Geriatric Pain Measure are both appropriate for use in geriatric pain populations. The McGill Pain Questionnaire (MPQ) is another useful measure of pain quality that provides a list of 78 descriptors of pain from which the user can pick words that can later be summed to yield a sensory, effective, and evaluative overall pain score. This well-validated measure has been translated into many languages, thus making it particularly appropriate for cross-cultural use. A short-form of the MPQ is also available. The Short-Form MPQ (SF-MPQ) correlates well with the original MPQ and is more practical for use in the clinical setting.
Unidimensional Pain Scales
Verbal pain descriptor (none, mild, moderate, severe)
Numerical rating scale (0 to 5 or 0 to 10)
Pain Thermometer
Faces Pain Scale
Multidimensional Scales
Brief Pain Inventory
Geriatric Pain Measure
McGill Pain Questionnaire (MPQ); Short-Form MPQ (SF-MPQ)
Measurement Tools in Older Patients with Cognitive Impairment
Doloplus, Doloplus-2
Pain Assessment Checklist for Seniors with Limited Ability to Communicate (PACSLAC)
Assessing Pain in Older Patients with Cognitive Impairment
Assessment of pain in older patients with cognitive impairment requires the use of a triangulated approach that includes self-report, caregiver report, and direct observation. Patient self-report can include responses to questions such as “How much pain do you have now” and the use of reliable self-assessment tools such as the visual analog scale or Faces Pain Scale. The same scale should be used to reassess the pain to determine the effects of treatment over time.
Types of behavior that suggest underlying pain include facial expressions (grimacing, frowning), vocalizations (noisy breathing), changes in activity patterns (eating, sleeping), changes in mental status (confusion, irritability), body movements (guarding, bracing), and interpersonal interactions (aggressive, disruptive, social withdrawal). Numerous observational tools are available and can help providers assess pain in older patients who are unable to communicate verbally. Recent systematic reviews have identified at least 10 behavioral assessment tools for measuring pain in older adults with cognitive impairment. Most of the scales, with the exception of the Doloplus, have been used only in small studies, and there is limited evidence of the instruments’ validity and reliability. The most promising scales for both practice and research appear to be the Pain Assessment Checklist for Seniors with Limited Ability to Communicate (PACSLAC), Abbey, and Doloplus-2.
Pharmacologic Management of Persistent Pain in Older Patients
Analgesic medications constitute the primary treatment used by physicians when managing older adults with persistent pain, and it is the most commonly reported method used by older persons with a persistent pain condition. For example, in one study of older black and non-Hispanic white adults with osteoarthritis, more than 80% of both groups reported regular use of prescription and over-the-counter (OTC) pain medications.
Barriers to effective pharmacologic management of pain in older adults are diverse and include age-related physiologic changes (described earlier), which often dictates altering the dose and frequency of analgesic administration. Most older adults with a persistent pain disorder have multiple chronic conditions such as diabetes, hypertension, and osteoporosis, and they must be taken into account when formulating a treatment plan. Many older adults experience polypharmacy (defined as the use of multiple medications, with five or more being a typical threshold criterion), which frequently complicates the pharmacologic management of pain. Various patient sociodemographic factors can also operate as barriers. Although adequate social support enhances adherence to medication, many older adults live alone with limited social support. In addition, many older adults cannot afford the high cost of certain pain medications. Furthermore, substantial numbers of older adults lack the necessary skills to read and process basic health care information, including understanding instructions on pill bottles, information present on patient handouts, and clinicians’ instructions about the side effects of medications. Low health literacy can lead to problems with medication adherence, such as taking too much or too little pain medication.
In older adults with persistent pain, commonly prescribed analgesic agents include nonopioids, opioids, and adjuvant therapies ( Box 34.2 ). Issues related to the safety and efficacy of these three analgesic classes are summarized briefly in the following sections.
Nonopioids
Acetaminophen
Nonsteroidal anti-inflammatory drugs (use in selected cases and with caution)
Opioids
Adjuvants
Antidepressants (nortriptyline, desipramine)
Selective norepinephrine reuptake inhibitors (duloxetine, venlafaxine)
Nonopioids
Acetaminophen is the most commonly prescribed analgesic for the treatment of mild to moderate persistent pain in older adults because of its low cost and overall safety profile. One meta-analysis found that up to 4 g of acetaminophen daily was modestly effective in reducing pain in comparison to placebo, with a standardized mean difference of −0.13 (95% confidence interval [CI] = −0.22 to −0.04). With respect to safety, acetaminophen toxicity is the leading cause of acute liver failure in the United States. Unintentional overdose remains the major cause of acetaminophen-induced hepatotoxicity, and the vast majority of affected individuals report having taken acetaminophen to treat pain. Nonsteroidal anti-inflammatory drugs (NSAIDs) continue to be one of the most commonly prescribed and consumed analgesic agents, particularly as OTC products. One meta-analysis examining the efficacy of oral NSAIDs reported an effect size of 0.29 (95% CI = 0.22 to 0.35) for pain reduction. Although oral NSAIDs are widely considered to be more effective pain relievers than acetaminophen, NSAID use has significant limitations in the form of renal, gastrointestinal (GI), and cardiovascular toxicity, particularly in older patients. When compared with younger patients, older patients are at increased risk of experiencing GI complications in the form of peptic ulcer disease and GI bleeding. Use of either cyclooxygenase-2 (COX-2)-selective inhibitor NSAIDs (e.g., celecoxib) or nonselective NSAIDs is associated with increased risk for myocardial infarction, stroke, and mortality. These safety concerns led the American Geriatrics Society to generate an updated pain management guideline that recommends the use of nonselective or selective NSAIDs in highly selected cases only and with “extreme caution.” Given the risks associated with oral NSAID use, increasing attention has focused on the development and testing of topical NSAIDs. Two topical NSAIDs have been approved for use by the U.S. Food and Drug Administration (both are diclofenac preparations), and a number of trials testing other topical NSAID formulations are currently under way. Although no long-term studies have been published, preliminary evidence suggests that topical NSAIDs produce fewer side effects and are better tolerated than oral NSAIDs. The COX-2 inhibitors do not appear to be more efficacious than nonselective NSAIDs, and there are no data that they are better tolerated. The promise of reducing GI toxicity is also still questionable.
Opioids
The short-term efficacy of opioids has been established in older adults for conditions such as osteoarthritis and painful neuropathies. In one meta-analysis, positive effect sizes were demonstrated for reductions in pain (effect size = −0.56, P < 0.001) and physical disability (effect size = −0.43, P < 0.001). However, the studies included in the meta-analysis were short-term (most lasted 8 weeks or less), and most excluded older adults with comorbidity, thus raising questions about the long-term efficacy and safety of opioids in typical older patients (i.e., those with multiple chronic conditions and taking multiple prescription medications). Though well accepted as a means of treating both acute and cancer pain, opioid analgesics remain controversial in the treatment of persistent non–cancer-related pain. Solomon and colleagues used Medicare claims data to examine the safety of selective and nonselective NSAIDs versus opioids for nonmalignant pain. Patients receiving selective NSAIDs or opioids experienced more adverse cardiovascular outcomes than did nonselective NSAID users. Although both nonselective and selective NSAID users had similar risk for fractures, opioid users were found to have a significantly increased risk for fractures, adverse events requiring hospitalization, and all-cause mortality. Study limitations included concerns about an inability to control for certain confounders (e.g., OTC analgesic use, functional status, cognitive deficits) and an inability to quantify the risk associated with distinct patterns of analgesic use. Despite these limitations, the findings provide strong support for additional studies to quantify both the risks and the benefits of opioid use (vs. other types of analgesics) when treating persistent pain disorders in older adults.
Adjuvant Agents
Commonly administered adjuvants include both antidepressants and anticonvulsants, and they are typically prescribed to treat neuropathic pain. Tricyclic antidepressants such as nortriptyline and desipramine are effective for the treatment of diabetic neuropathy and post-herpetic neuralgia. Although the use of low doses can mitigate the occurrence of side effects, many older adults experience treatment-limiting anticholinergic side effects in the form of dry mouth, urinary retention, and constipation, as well as increased risk for falls. Duloxetine, a selective serotonin-norepinephrine reuptake inhibitor (SSNRI), has also been shown to be effective in the treatment of diabetic neuropathy and to have a superior safety profile relative to the tricyclic antidepressants. Venlafaxine, also an SSNRI, has been shown to be effective in lowering pain levels in patients with painful diabetic neuropathy. Nausea is a commonly reported side effect with both SSNRI agents. Anticonvulsants (pregabalin and gabapentin) may be useful in treating neuropathic pain disorders in older adults. However, side effects in the form of sedation, confusion, and peripheral edema can limit the use of these medications in older patients.
Practice Recommendations
For many classes of pain-relieving medications, older patients have been shown to have increased analgesic sensitivity. However, it is important to remember that older adults constitute a highly heterogeneous group, so dosing guidelines need to be based on careful consideration of a patient’s pain, its impact on functional status, and the patient’s comorbid conditions and other factors (e.g., polypharmacy and sociodemographic and health literacy issues). There are currently no geriatric-specific dosing guidelines. Since advancing age is associated with a greater incidence of treatment side effects, the adage “start low and go slow” is a reasonable rule of thumb when initiating a trial of an analgesic in older patients. This does not mean that one should “start low and stay low,” which can contribute to undertreatment. Sustained-release analgesic preparations are recommended for continuous pain, along with the use of short-acting agents to treat pain flares and breakthrough pain. Although long-acting agents are more convenient (and probably associated with greater adherence), there is no evidence that they provide better pain relief.
If treatment goals are not being met and the patient is tolerating the therapy, advancing the dose is reasonable before prescribing another therapy.
Nonpharmacologic and Self-Management Approaches to Managing Persistent Pain
A range of nonpharmacologic pain management (NPM) modalities are available and should be considered when managing pain in older patients. Strategies popular among older adults include exercise, the application of heat or cold, and nutritional supplements. The American Geriatrics Society guideline recommends NPM as an adjunctive treatment to pharmacologic management. The guideline specifically advises practitioners to consider recommending exercise, cognitive-behavioral therapy (CBT), and patient education for long-term pain management. Complementary and alternative approaches such as massage, transcutaneous electrical nerve stimulation, or acupuncture may be initiated on a trial basis to find strategies that offer short-term relief in the event of pain flare-ups. Fear of pain can result in avoidance of movement and consequentially reduced physical function, which exacerbates the pain experience. With regular moderate exercise, older adults can increase physical function, slow physical deterioration, and improve joint range of motion. Prescribed exercise should be individualized, be supervised for those with either severe pain or significant physical disability, and include flexibility, strength, and endurance exercises. Poor coping skills and negative beliefs about pain and its management make managing persistent pain difficult regardless of patient age. CBT is a psychological therapy that aims to promote and reinforce self-management and positive health behavior and pain beliefs. CBT is recommended for older adults with persistent pain disorders and can be provided as a structured, professionally led program that can be delivered on an individual or group basis, face to face or online. However, the limited number of providers skilled in delivering CBT may restrict the availability of this particular therapy.
Most older adults express a willingness to try new strategies and voice preference for self-delivered strategies that promote independence and control. An increasing number of papers on the management of persistent pain in older adults have been published, and there is increasing awareness that self-management of persistent pain is a viable strategy for older populations. The American Geriatrics Society guideline recommends encouraging older patients to locate information about self-help strategies and participate in pain education to increase awareness of pain treatments and skills important in pain management, such as goal setting. Pain self-management is a patient-centered process that involves the acquisition, practice, and execution of skills needed to respond to and control pain and its associated symptoms. Successful and optimized pain management requires that older patients be confident and able to manage the everyday symptoms and consequences of pain. To achieve this, older patients must adopt responsibility for managing their pain, along with support from others. Identifying older patients who are already effective self-managers and those who would benefit from additional support remains a difficult area, however. Self-efficacy, or confidence in one’s ability to self-manage pain, is an important psychological predictor of an individual’s capability for effective self-management and can be assessed in the clinical setting. Other factors, such as pain beliefs, attitudes, and motivation, also influence participation in self-management. For older patients who require additional support, a variety of materials and interventions are available, including professional or lay-led group courses (delivered in person or online), educational resources (i.e., workbooks, leaflets, and CDs), and self-help groups. The efficacy of self-management programs for older adults that specifically focus on generalized management of persistent pain remains controversial, with some reviews suggesting little patient benefit. Conversely, disease-specific programs, such as those developed for arthritis, have demonstrated more consistent benefit, including moderate reductions in pain and enhanced psychological well-being. Decisions on how best to support older patients’ self-management will largely be determined by what is available and accessible to the patient locally, but to the extent possible, older patients should be encouraged to choose between available formats and select individual strategies that best meet their needs.
Older patients’ use of NPM and self-management strategies varies extensively, and barriers include a lack of advice and support from their primary care providers, affordability of and access to certain strategies, and the pain management attitudes of professionals, older patients, and their caregivers. It is important that clinicians discuss NPM and self-help strategies with older patients. These strategies can improve quality of life and reduce pain and the associated impact of pain on daily life through the adoption of positive pain behavior and coping responses. Although many strategies may appear harmless, unknown risks may exist. For example, some dietary supplements or herbal remedies may pose a risk to older patients when taken with particular pharmacologic agents. It is therefore imperative that clinicians ascertain the full extent of their older patients’ pain and pain management experiences and consider cultural, lifestyle, and socioeconomic factors that may influence these experiences. This must be done in a manner that identifies the use of risky NPM strategies that have the potential to cause harm but still encourages patients to play an active role in the management of their pain.
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