Although pain is not an inevitable aspect of aging, older persons are at greater risk for many disorders associated with pain. Delineating the prevalence of pain with advancing age is a challenge because epidemiologic studies differ in the age cut points, methods of data collection and measurement of pain, and the types of pain studied. However, data across settings and samples suggest that pain is prevalent and a significant factor impacting quality of life. Approximately 65% of older persons living in the community have persistent pain^* conditions^8,9 with more frequent pain (up to 85%) noted in those living in institutions, particularly nursing homes,^10,11 and those in the final months of life (over 80%).^12,13 Prevalence of pain in hospitalized older adults is also high with 67% on geriatric units reporting pain present.¹⁴

A nationally representative sample of American adults showed back, knee, and shoulder as the most prevalent pain sites in those 65 to 69 years old, with little change in this pattern in cohorts of those 90 years old or older.⁸ Over 60% of older adults report pain in multiple locations with women reporting more pain sites and a greater intensity of pain than male counterparts,^15,16 which impacts physical and psychosocial function. Older women and those with obesity, musculoskeletal conditions, and depressive symptoms are at higher risk for pain.⁸

Other common conditions associated with pain in older persons include atherosclerotic peripheral vascular disease, herpes zoster, trigeminal neuralgia, diabetic neuropathy, temporal arteritis, polymyalgia rheumatica, osteoporosis with vertebral compression fractures, lumbar spinal stenosis, and fibromyalgia.¹⁷ Also, injuries, such as hip fractures resulting from falls, are more common in this population and may result in both acute and chronic pain.

Pain in the older adult interferes with the ability to manage and recover from health challenges given its important and often unrecognized impact on impaired function and quality of life.¹⁸ Acute and persistent pain have adverse health outcomes in older people.¹⁹ Poorly managed acute pain contributes to delayed ambulation, increased incidence of delirium and cognitive dysfunction, respiratory complications, longer hospitalization, and mood disorders.²⁰ Additionally, long-term consequences include impaired ability to complete activities of daily living (ADL), impaired mobility development of persistent pain, and cardiovascular disease.^19,21,22

More widely studied, persistent pain is known to negatively impact older adult physical and psychosocial function, including impaired nutrition and sleep, functional abilities, mood and cognitive function, and social interactions.^23,24,25 Pain from osteoporosis, osteoarthritis, and chronic back pain has been shown to significantly affect ADL, placing the older adult at risk for declining health and potentially institutionalization.^26,27 According to Hunt et al.,⁹ 43% of those with dementia are able to acknowledge and self-report significant functional limitations, including the ability to perform ADL.

Combined with impaired physical health, the decline in social and recreational activities produces emotional distress, contributing to depression,^8,28 which is capable of worsening both pain and disability.²⁹ Pain-related factors that worsen health-related quality of life include pain presence, pain severity, and number of pain sites.^{6,10,25,30,31,32} Persistent pain also is associated with frailty, a syndrome of physiologic decline, and should be a component assessed when determining frailty phenotype to improve the prediction of adverse outcomes.³³

Given these potentially serious pain-related consequences, evidence that pain is commonly undertreated or untreated in older adults is disturbing. Among those with pain, a significant portion of those over age 65 years do not receive analgesics or receive inadequate treatment, including 53% of elders transitioned from acute to skilled nursing care,³⁴ 17% to 65% of institutionalized elders,^10,11,35 51% of elders admitted to emergency departments with pain complaints,^20,36 and 20% of elders living with pain in the community.³⁷ Older patients in emergency departments are more likely to experience delays in analgesic treatment and have acute pain undertreated compared to younger patients.³⁸ Pain, depression, and functional limitations due to pain are particularly undertreated in low-income and minority older populations.³⁹

The diagnosis and treatment of pain in older persons is more difficult in those who present with multiple medical problems and a history that reveals many potential sources of pain.
Although there is an undeniable need to prevent harm from pain-relieving treatments, this focus must be balanced with a concerted effort to avoid pain-induced harm. Guidelines for the assessment, treatment, and monitoring of older patients with pain have been widely distributed advocating for individualized approaches to pain and balancing concerns for the safety and efficacy of treatments.^40,41,42

It is time to replace unrealistic fears and mistaken beliefs with guidelines that delineate prudent, safe, effective use of available treatments. Approaches to managing pain in older adults should incorporate noninvasive treatments, along with tailored pharmacologic management, based on a careful risk/benefit analysis of treatment options and the older person’s unique characteristics and goals.⁴³

Mounting evidence suggests that strong unrelenting pain changes the structure and function of nerves that create widespread degenerative alterations in brain functioning,^44,45 which may explain the learning, memory, and emotional difficulties experienced by older adults with persistent pain.⁴⁶ Physiologically, aging alters functions, including a degeneration of peripheral neuronal structures, which slow transduction and transmission involved in signaling pain.⁴⁷ These changes may result in a slowed pain response, but aging does not decrease sensitivity to pain, which may actually increase with age.⁴⁸ Once pain is established, the lower density of descending inhibitory circuits and an impaired ability to recover from hyperalgesic states are attributed to aging.⁴⁹ Although some of these changes are partially reversible with effective treatment,^50,51 changes in endogenous pain modulation increase older adults’ risk for developing persistent pain following an illness, surgery, or trauma.⁵²

Concerns arise regarding how pain processes, including judgment of its presence and severity, is experienced in those with dementia. Although research is mixed, recent studies suggest persons with Alzheimer disease are less sensitive to the detection of thermal pain but do not differ in affective response to unpleasant stimuli, contributing to greater pain and potential damage before identifying and reporting pain.⁵³ Thus, cognitively impaired older adults are able to feel painful stimuli⁵⁴ and may have heightened pain sensitivity.⁵⁵ Assuming that older adults, particularly those with cognitive impairment, experience less pain makes them vulnerable to undertreatment of pain and its consequences.^56,57 Although there are instances of atypical presentations of clinical pain in older adults (e.g., silent myocardial infarctions and the absence of abdominal pain with peptic ulcer disease), these exceptions should not be used to suggest that older adults, particularly those with cognitive impairment, feel less pain.

A comprehensive approach to assessment is necessary when evaluating pain in older adults and developing an effective treatment approach, including identification of the underlying cause of pain, pain characteristics, and impact on physical and psychosocial function and quality of life.⁵⁸ The scope and nature of the pain assessment will depend on a number of factors such as the physiologic stability of the patient, whether the situation is an emergency or planned event, and the severity of the presenting pain complaint. If the older adult presents in moderate to severe acute pain (e.g., greater than 4 on a 0-to-10 numeric rating scale), the first priority is to complete an initial, rapid pain assessment and treat the pain.^40,59 Once the older person’s pain is alleviated, a comprehensive pain assessment should be completed.

As with younger patients, self-report of pain is the criterion standard for determining pain presence and severity. The numeric rating scale, verbal descriptor scale, and faces pain scale are the most established tools for the alert, cognitively intact older adults.⁶⁰ The Iowa Pain Thermometer demonstrated comparable results to these scales and is most preferred by many older adults.^61,62 Cultural differences in tool understanding and preference also inform the need to solicit individual tool preferences.^63,64 These scales can be used more effectively in older persons by addressing sensory deficits (uses eyeglasses, hearing aids, large font/bold print written tools, etc.). Cognitive impairment can result in underreporting of pain; however, recent studies document that standard assessment techniques can be used effectively in older adults with mild to moderate cognitive impairment.^65,66 It is useful to adopt more than one validated tool for use in clinical settings to accommodate needs and preferences of different older patients. All team members (including caregivers) need to use the tool that patient prefers consistently for all pain assessments.

As a multidimensional experience, pain evaluation includes intensity, affect (how bothersome, distressing and effect on mood), sensory qualities (such as aching, stabbing, burning), spatial quality (e.g., location), temporal quality (including pattern and duration), and impact on or interference with daily activities (including physical and psychosocial functioning).¹⁷ Multiple biopsychosocial factors (e.g., anxiety, depression, beliefs, insomnia, fear avoidance, biomechanical issues) contribute to the experience of pain and should be evaluated for their contribution to impairment or dysfunction.⁶⁷ Evidence of pain impact includes disrupted social and family relationships, changes in eating and sleeping patterns, and altered mood and ability to continue previous activities. Determining the impact of pain on the older adult’s life requires gathering information on key quality of life variables from different sources, including the older adult, significant others, other health care workers, roommates, and activity therapists. The Brief Pain Inventory (BPI) is useful in many settings because it records dimensions of pain in addition to intensity (e.g., interference with functionality).⁶⁸ Other tools are available that gather data on pain and its impact in a clinically useful manner, including one called the PEG, that examines three BPI items of Pain intensity, Enjoyment in life, and General activity.⁶⁸

Expanded assessments including the underlying conditions known to be painful and comorbid diseases, the desired and undesired effects of prior and current pain treatments, and current medications (including over-the-counter drugs) provide important information to guide treatment planning. A complete physical examination of the pain source, including potential pain contributors such as leg length discrepancy and myofascial pain, focuses on the most common sources of pain: the musculoskeletal, peripheral vascular, and neurologic systems. Laboratory tests to determine renal and hepatic functioning may be indicated, but diagnostic tests should be used sparingly given that more than half of older patients with radiographic evidence of degenerative joint disease are pain-free and imaging studies are often not necessary or useful.⁶⁹

For a comprehensive review of pain assessment, the reader is referred to the clinical practice guidelines on acute and persistent pain available through the University of Iowa Csomay Center for Gerontological Excellence (http://www.iowanursngguidelines.com).^41,70

When the patient is unable to reliably self-report the presence or nature of pain due to severe cognitive impairment or critical illness, clinicians rely on a combination of assessment strategies to fill this void. An approach for recognizing pain in nonverbal
older adults includes a process of data gathering that includes (1) attempting self-report, (2) identifying pathologic conditions or procedures that usually cause pain, (3) identifying behaviors associated with pain, (4) obtaining input from a family member or others knowledgeable of the older adult, and (5) attempting an analgesic trial to verify that suspected behaviors are pain-related.⁵⁸

Even if the patient is unconscious, intubated, or chemically paralyzed, the clinician’s understanding of the pain typically associated with the medical conditions/procedures allows them to make assumptions about the presence of pain and guide pain prevention and treatment interventions regardless of cognitive/verbal abilities. A good history and physical examination provides information on pain-related diagnoses and conditions that support a judgment of pain present.

Directly observable behaviors, such as grimacing, moaning, guarding, bracing, and posturing as well as those less common such as agitation, aggression, restlessness, resisting care, and changes in usual behavior patterns, are recognized as important indicators of pain in those who cannot communicate their pain verbally.^71,72 Among the behaviors displayed by people unable to communicate their pain, facial expression is being recognized as a common and essential element of the behavioral assessment.^71,73 A large number of behavioral pain assessment tools have been developed for use in this population. Systematic reviews have evaluated the strengths and limitations of existing behavioral tools reaching similar conclusions that there is no single tool appropriate for all patients and settings.⁷⁴ Updates on existing tools and psychometric properties, as well as recommendations for use, are available.^54,75 Research is ongoing to refine pain behavior indicators and tools to advance clinically useful methods of pain evaluation in this challenging population.⁷⁶

Evidence from any of the aforementioned steps can inform clinician judgment and decision making about pain presence in the older person with advanced dementia. Use of an analgesic trial has shown positive effects in improving disturbing and distressing behaviors,⁷⁷ confirming underlying pain etiologies. Pain treatment planning is often oversimplified, expecting patients to respond similarly to the same noxious stimuli and therapeutic intervention. This may work with mild, fleeting pain, but when pain is severe and/or persistent, developing a safe, effective plan needs to be tailored to the patient’s unique perceptions, capabilities, comorbid conditions, and responses. The initial goal of any pain treatment plan is to find and eliminate its source if possible and then balance concerns for pain reduction, functional improvement, and avoidance of treatment-related harm. Frequent, ongoing reassessments enhance understanding of the patient’s unique pain and response to therapy and refinements need to ensure optimal safety and effectiveness.

With the exception of the rectal route, the rate of medication absorption is not typically affected by aging. The pattern of drug distribution does change because of less total body water and more body fat seen in many older adults. This favors the distribution and accumulation of lipophilic (fentanyl) agents while decreasing that of hydrophilic (morphine) drugs. The decline in serum protein concentrations with age can increase the bioavailability of drugs, like nonsteroidal anti-inflammatory drugs (NSAIDs), that are highly protein-bound.⁷⁸ This effect is magnified in frail, protein-depleted older adults⁷⁹ and patients taking multiple medications that displace NSAIDs from protein-binding sites.

The metabolism and excretion of NSAIDs is often compromised due to the smaller size, lower blood flow, and reduced function of the liver with age. These hepatic changes combined with fewer drug-metabolizing enzymes, increase drug elimination time, and slow the metabolism required to produce active metabolites. Reductions in renal size, glomerular filtration rate, and renal blood flow raise the risk of side effects and toxicity from slowed elimination of the drug and active and toxic metabolites.⁸⁰ NSAIDs can further contribute to this slowed clearance by lowering renal blood flow and glomerular filtration rate through its antiprostaglandin effect.

Pharmacodynamic changes with aging increase sensitivity to both the desired and undesired effects of opioids.⁸¹ Combined with other age-related changes in the neurologic and pulmonary systems, there is a greater risk of sedation, sleep apnea, and respiratory depression with opioid analgesics.⁸² Combined, these pharmacokinetic and pharmacodynamic changes warrant using lower doses and longer dosing intervals with advanced age, especially with known hepatic or renal impairment, and frailty, with or without cognitive impairment.⁷⁹