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Winter 2011
Persistent Pain — Three Keys to Effective Pain Management in EldersBy Julie Testman, PharmD, BCPS, CGP Pain, defined as an unpleasant sensory and emotional experience, is common among older patients yet often goes unrecognized and is frequently undertreated. Chronic pain is described as pain that lasts longer than three months or, perhaps more appropriately, as pain that persists beyond the expected time frame for healing.1,2 Unfortunately for many older patients, the term “chronic pain” has become a label associated with negative images and stereotypes often linked to long-standing psychiatric problems, futility in treatment, malingering, or drug-seeking behaviors.3 For this reason, the term “persistent pain” is preferred in the medical literature and will be used throughout this article as it may foster a more positive attitude toward pain identification and treatment by both patients and prescribers. Persistent pain is an issue for up to 40% to 60% of community-dwelling elders and 40% to 80% of those who are institutionalized.4 In the elder population, inadequately treated pain frequently leads to other problems, including depression, anxiety, sleep disorders, decreased quality of life, and reduced independence.5,6 In the United States, it is estimated that up to 80% of older individuals residing in long-term care facilities experience pain that impairs functionality and negatively affects their activities of daily living, mood, and quality of life.7 Effective pain management in older patients requires physicians to be skillful in the appropriate assessment of pain, possess knowledge and skill related to the appropriate use of pharmacologic and nonpharmacologic interventions, and be aware of the aspects of pain management unique to this population.8 Concerns about drug toxicities, drug interactions, and patients’ fear of treatment are all factors warranting consideration in managing patients’ pain, but these issues do not have to become barriers to effective treatment. Assessing Elders’ PainThere are multiple causes of pain that can affect older patients, and pain is generally best treated when the specific underlying cause is identified. Musculoskeletal disorders probably account for the most common causes of pain in elders. Osteoarthritis may affect 80% of individuals over the age of 65 and most of those affected experience significant pain. Cancer is also a cause of severe pain in older patients, especially near the end of life. Additional painful medical conditions more common in older patients include herpes zoster, temporal arteritis, polymyalgia rheumatica, and atherosclerotic peripheral vascular disease.3 Pain has been described as the “fifth vital sign” and as such, the American Geriatrics Society recommends that all elder patients should be assessed for evidence of persistent pain upon initial presentation or admission to any healthcare service. Because no objective biological markers for the presence of pain exist, the current best indicator of the pain experience is the patient’s own report, which must include an assessment of pain intensity and an evaluation of the pain’s effect on daily function. Accurate pain assessments begin when clinicians believe patients and take their pain complaints seriously. Inadequate assessment strategies result in inadequate pain management.2,3,9,10 A comprehensive history and physical examination are essential components in pain assessment and evaluation. Important aspects of the pain assessment history include pain characteristics, the relationship of pain to impairments in physical and social function, the patient’s attitude and beliefs about pain and its management, the effectiveness of previous treatments, satisfaction with current pain management, social support, and healthcare accessibility. Physical examination and diagnostic studies should be used to confirm the patient’s history and pinpoint the cause(s) of pain. Direct observations of physical function and assessments of psychological and cognitive function are also important components of the physical examination.2,3,9 Barriers to Pain AssessmentThe proper assessment of pain in older patients can be quite challenging and requires an appreciation for an atypical presentation in this population. For example, pain can present atypically as delirium, depression, irritability, insomnia, or agitation.11 A comprehensive pain assessment should be performed on any patient presenting with these symptoms. Failure to recognize the atypical presentation of pain may lead to inadequate pain treatment and the use of unnecessary medications for conditions that may be alleviated by appropriately treating pain as the underlying cause. Older patients may fail to report pain for numerous reasons. Because many older patients expect to have pain, they may be impassive or stoic and reluctant to complain. Others may be ambivalent about the effectiveness of pain medications or may worry that their pain is a sign of a serious illness. They may also be fearful that reporting their pain could lead to additional testing, added medications, or additional medical costs. Additionally, communication may be impeded by sensory deficits such as impaired hearing or poor vision.5,12,13 Pain assessment may be particularly difficult in patients with cognitive or speech impairments who are unable to articulate their symptoms. Signs of pain in these patients may include grimacing, unusual focal or aggressive behavior, increased body movement, fluctuating vital signs, changes in sleep or appetite, depression, and worsening cognition.14,15 A variety of pain scales/assessment techniques to address the unique needs of these patients are available. Pharmacokinetic and Pharmacodynamic AlterationsConsistent with pharmacologic therapy for older patients in general, these patients are more likely to experience adverse drug events with various analgesic medications. They are also more likely to have an increased sensitivity to the effect of analgesic agents, especially opiate analgesics.13 Despite these increased risks, analgesics can still be used safely and effectively in patients when age-associated alterations in pharmacokinetics and pharmacodynamics are considered. Changes associated with normal aging may present pharmacological concerns for older patients. Many chronic diseases that are more prevalent among older adults may contribute to these effects. As age progresses, blood flow, hepatic capacity, and renal function all decline and complicate the absorption, distribution, metabolism, and elimination of drugs.16,17 For example, the gastrointestinal absorption of drugs may be affected by slower transit times, prolonging the effects of continuous-release enteral medications. Alternatively, disorders that alter gastric pH may reduce the absorption of some medications. Substantial reductions in hepatic mass, blood flow, and enzymatic capacity (particularly in the cytochrome P450 system) that result from aging can lead to slowed drug metabolism and more pronounced adverse effects in older patients. Glomerular filtration rate also decreases with advancing age in many patients, resulting in decreased medication clearance and prolonged effects of active drug metabolites. 10,16 Older patients are often increasingly sensitive to drug pharmacodynamics and are typically at higher risk for the adverse effects of many analgesic agents. For example, anticholinergic side effects can be particularly problematic in older patients, resulting in increased confusion, constipation, dry mouth, or urinary retention. These effects may be enhanced by comorbid neurologic disease processes. As a result of these age-related alterations in pharmacokinetics and pharmacodynamics, a widely acceptable tenet in geriatric prescribing is recommended: start low and go slow. Medications should be initiated at low doses and titrated slowly to the desired effect while minimizing the potential for any adverse drug reactions.10,16 General Treatment ApproachOlder patients with functional impairment or diminished quality of life as a result of pain are candidates for pharmacologic therapy. Treatment decisions should be based on an evaluation of the risk vs. the benefit of individual drug therapies. Carefully considering the characteristics of the chosen analgesic agents and regularly monitoring patients for any potential adverse effects maximizes positive outcomes. Elder patients constitute a heterogeneous population. Optimum analgesic doses and common side effects are difficult to predict. As previously stated, it is best to “start low and go slow” in these situations to optimize pain relief and minimize adverse effects. Always use the least-invasive method of drug administration. The oral route of medication administration is preferred (if possible) to maximize convenience for the patient. For acute, rapidly fluctuating pain, the IV route may be considered, as it provides a more rapid onset and has a shorter duration of action. Subcutaneous and intramuscular routes of administration are also commonly used but may demonstrate larger fluctuations in absorption. For patients with swallowing difficulties, transdermal, rectal, or transmucosal formulations of available medications may be necessary. The timing of medication administration is an important consideration. Analgesics intended for the relief of continuous pain should be administered around the clock to maintain comfort. This can be accomplished with long-acting or sustained-release medication formulations. Short-acting drugs with a more rapid onset of action should also be available for breakthrough pain. Intermittent or episodic pain is usually treated with analgesics prescribed as needed. However, in patients with cognitive impairment who may not be able to report pain or request an analgesic medication, this approach may not be the best choice. Instead, scheduled administration prior to any anticipated pain episodes should be considered. Severe episodic pain requires the use of rapid- and short-acting medications. A combination of pharmacologic and nonpharmacologic treatment strategies may enhance the relief of persistent pain in many patients. Examples of nonpharmacologic measures that have been shown to be effective include physical therapy, cognitive behavioral therapy, and patient/caregiver education. “Rational polypharmacy” may be necessary for patients who do not experience pain relief with monotherapy. A combination of two or more medications with complementary mechanisms of action may be used to optimize pain relief while minimizing the potential for adverse or toxic effects associated with higher doses of a single agent. Pharmacologic Therapy: Nonopioid AnalgesicsAcetaminophenBecause of its relative safety compared with traditional nonsteroidal anti-inflammatory drugs (NSAIDs), acetaminophen is recommended as a first-line therapy for pain. It is effective in the management of both osteoarthritis and lower back pain and is not commonly associated with adverse renal effects, significant gastrointestinal bleeding, or cardiovascular toxicity. Currently, the maximum recommended dose is usually 4 g daily; however, reduced maximum dosages may be considered in older patients, particularly those with hepatic insufficiency or a history of alcohol abuse. Patients and/or caregivers should be educated regarding the maximum recommended dose of acetaminophen due to its availability over the counter (OTC) and its inclusion in many combination products, both prescription and OTC. NSAIDsAcetaminophen may not provide adequate efficacy for persistent pain with an inflammatory component. In these cases, NSAIDs may be considered. However, caution must be used as older patients are at higher risk for several adverse effects of these medications compared with the general adult population. The potential for gastrointestinal toxicity, which increases in frequency and severity with age, is probably the most well-known concern with this medication class. Patients with reduced creatinine clearance, gastropathy, cardiovascular disease, or heart failure also warrant particular caution with use of these agents. The cardiovascular risks associated with NSAIDs are also of concern. Some traditional NSAIDs (eg, ibuprofen) have the potential to interfere with aspirin’s antiplatelet effect. In 2006, the FDA issued a warning regarding the coadministration of aspirin and ibuprofen and the risk of this effect. The cyclooxygenase-2 selective inhibitors rofecoxib and valdecoxib have been withdrawn from the market due to concerns of adverse cardiovascular events; celecoxib is the only agent within this class still available. Differences in risk have also been identified among the traditional agents. Diclofenac may be associated with a higher cardiovascular risk, while several studies indicate that naproxen possesses less cardiovascular toxicity. According to the most recent American Geriatrics Society Panel of the Pharmacological Management of Persistent Pain in Older Persons, “the decision to prescribe NSAIDs in the management of persistent pain in older adults demands individualized consideration.” Decision making regarding treatment with these agents should include a thorough evaluation of patient comorbidities, concomitant medications, and risk factors (eg, cardiovascular, gastrointestinal, renal function, drug-drug interactions). The potential benefits of therapy should always be weighed against the potential risks in individual patients. Pharmacologic Therapy: Opioid AnalgesicsOpioid analgesic medications act by blocking receptors in the central nervous system (brain and spinal cord), resulting in decreased pain perception. Although older patients may be more sensitive to the analgesic effects of these medications, they remain an important component in the control of moderate to severe pain. Opioid analgesics have no ceiling to their analgesic effects and have been shown to relieve multiple types of pain. Common adverse effects associated with opioid therapy include constipation, nausea and vomiting, sedation, impaired judgment, impaired psychomotor function, and respiratory depression. The tolerability profile of a particular medication is a very important consideration in older patients, as many of these potential effects can result in very serious consequences (eg, falls as a result of dizziness, drowsiness, and/or motor imbalance). As previously discussed, using lower starting doses, longer dosing intervals, and/or slower titration schedules can minimize the risks for some of the potentially adverse effects of opioid analgesics. Constipation is one complication of opioid drugs for which older patients do not develop a tolerance. This effect is important to recognize since it can be effectively prevented and relieved. The management of opioid-induced constipation can include increasing fluid intake and maintaining mobility. For many patients, the use of potent stimulant laxatives such as senna or bisacodyl with or without a stool softener (docusate sodium) is necessary. Impactions should be removed and obstruction ruled out before therapy with a stimulant laxative is initiated. The adverse effect profile can also vary significantly among opioid analgesics; therefore, medications with a more favorable tolerability profile (especially regarding central nervous system and gastrointestinal effects) should be chosen for elder patients. Pentazocine should also be avoided in older patients because it is associated with increased delirium and confusion in this population. Meperidine can cause delirium seizures, dysphoria, and myoclonus secondary to accumulations of the metabolite normeperidine, which is more common in those with poor renal function. Regardless of the opioid agent chosen, patients should receive continuous and ongoing monitoring for efficacy and the occurrence and intensity of opioid-related adverse effects. Adjuvant Drugs and Other Medications for PainA variety of other medications not formally classified as analgesics have been found helpful for certain specific pain problems. Although a discussion of these agents is beyond the scope of this article, commonly used drug classes may include tricyclic antidepressants, serotonin-norepinephrine reuptake inhibitors, anticonvulsants, corticosteroids, and topical lidocaine, among others. These agents may be used alone, but the effects are often enhanced when used with other analgesics and nondrug strategies.10 Final ThoughtsPain is common in older patients, often presents atypically, and can lead to the development of additional symptoms and conditions if unrecognized, untreated, or undertreated. All physicians have a responsibility to ensure a better quality of life for elder patients who are experiencing pain. Pharmacologic therapy should be adjusted based on the potential for age-associated alterations in pharmacodynamic and pharmacokinetic parameters, and ongoing monitoring should be performed for all patients receiving analgesic medications to assess for efficacy, safety, and tolerability on an individualized basis. — Julie Testman, PharmD, BCPS, CGP, is an assistant professor of pharmacy practice at the University of Charleston School of Pharmacy in West Virginia. References
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