Author: Caroline Ha, MD
Sub-optimally managed pain can increase healthcare utilization and expenditures, contribute to family and caregiver distress, diminish quality of life and functional independence, and affect sleep, appetite, and even cognitive function (Mercadante & Arcuri, 2007; Rastogi & Meek, 2013).Optimizing pain control in the elderly requires attention to several issues:
A comprehensive pain assessment includes evaluation of not only physical pain but also any emotional, spiritual, or social components of pain (Rastogi & Meek, 2013).
In renal insufficiency, the opioids of choice are fentanyl, buprenorphine, and methadone. Hydromorphone, hydrocodone, and oxycodone may be used with careful monitoring; dose reductions may be prudent. Morphine and codeine should have their doses reduced and may be best avoided, due to accumulation of neurotoxic metabolites (Pergolizzi, et al., 2008; Johnson, 2007).
In hepatic insufficiency, acetaminophen usage should be limited to less than 2g/day. Fentanyl may be the opioid of choice (Johnson, 2007; Bosilkovska, Walder, Besson, Daali, & Desmeules, 2012).
"Addiction" is a syndrome of psychological dependence and compulsive drug-seeking behaviors. Although many patients may exhibit physical dependence on opioids—characterized by withdrawal symptoms after sudden discontinuation of the opioid—addiction is infrequent. Patients concerned about opioid addiction should be educated regarding the differences between addiction and physical dependence (Fallon, Cherny, & Hanks, 2011).
Opioids should be initiated at the lowest effective dose in the elderly. A long-acting medication can be added for chronic pain; breakthrough doses used with a long-acting regimen should be 5-15% of the long-acting dose. Total daily doses may be titrated by 30-50% after 24 hours. If opioids need to be switched, the dosage should be reduced by at least 25-50% to account for incomplete cross-tolerance (Rastogi & Meek, 2013; Yennurajalingam, Braiteh, & Bruera, 2005; Fallon, Cherny, & Hanks, 2011)
There is a high incidence of pain in the elderly: some sources indicate it is as high as 30-50% of people aged 65 and older, and 50-75% in people over the age of 85. Unfortunately, pain in the elderly often goes unrecognized or inadequately treated (Rastogi & Meek, 2013). Although the response to mild pain in the elderly seems to be blunted, studies indicate that older patients may have increased sensitivity to severe pain (Pergolizzi, et al., 2008).Pain can be classified as acute or chronic.
Pain can be further categorized as nociceptive, neuropathic, or psychogenic (Portenoy, 2012). These categorizations can be helpful in making treatment decisions. A thorough pain assessment is therefore necessary to optimize pain management.In elderly patients, there are several other factors that must be considered before instituting a pain regimen.
A thorough pain history is essential in identifying the type and cause of pain.
Categorizing pain as nociceptive, neuropathic, or psychosocial can be helpful since the initial management for these categories differs significantly.
When planning pain management for elderly patients, the patient's functional independence, cognition, and social and family support must be assessed.
If substance abuse is a possibility, a screening tool such as the CAGE questionnaire can be used. It is also useful to investigate the patient's comorbidities and other medications, as these can also affect how the patient responds to any prescribed analgesics (Delgado-Guay & Bruera, 2008).
Additionally, it is important to recognize that in elderly patients—especially frail ones—a "normal" serum creatinine does not rule out the possibility of renal impairment. Therapy may need to be tailored through dose reduction or outright avoidance in the presence of renal insufficiency. (Mercadante & Arcuri, 2007)
The World Health Organization's analgesic ladder for cancer pain provides a framework for managing cancer pain. Its usage has also been extended to the treatment of non-cancer pain. The ladder recommends step-wise escalation of analgesics. In the elderly, it is good practice to avoid polypharmacy and start or adjust only one medication at a time whenever possible. Medications should be delivered by the least invasive route available—generally oral or transdermal (Pergolizzi, et al., 2008).
Pharmacological therapy is often more effective when combined with non-pharmacological interventions, such as physical therapy, counseling, pain education, and complementary therapies like acupuncture (International Association for the Study of Pain, 2006; Yennurajalingam, Braiteh, & Bruera, 2005).
Step 1, Non-opioid analgesics +/- adjuvants
Acetaminophen has antipyretic and analgesic properties and is generally well tolerated. However, lower doses are recommended for elderly patients, and daily doses should be limited to less than 2 or 3 g/day to reduce the risk of liver injury (Rastogi & Meek, 2013; Bosilkovska, Walder, Besson, Daali, & Desmeules, 2012).
Nonsteroidal anti-inflammatory drugs (NSAIDs) may cause several adverse effects, including liver and kidney injury as well as gastritis and gastrointestinal bleeding, Elderly patients are at increased risk for adverse effects, and chronic NSAID use should be avoided when possible. Elderly patients utilizing chronic NSAID therapy may benefit from a proton pump inhibitor to reduce gastrointestinal adverse effects (Rastogi & Meek, 2013; Portenoy, 2012). Commonly used adjuvants for pain include tricyclic antidepressants (TCAs), selective serotonin norepinephrine reuptake inhibitors (SNRIs), corticosteroids, and antiepileptic medications. In the elderly, the TCAs are best avoided due to the risk of adverse effects; nortriptyline and desipramine are preferred to amitriptyline if safer options are not available. Corticosteroids can be used in short courses to assist with reducing inflammation and pain, and is also helpful for fatigue and appetite. However, corticosteroids can cause several undesirable effects, including insomnia, gastritis, gastrointestinal ulceration, delirium, osteoporosis, and glucose intolerance, especially when used for prolonged periods.
The antiepileptic medications gabapentin and pregabalin are especially useful for neuropathic pain; however, doses need to be adjusted in renal insufficiency. In the elderly, antiepileptics should be titrated slowly to reduce risk of sedation, dizziness, and falls (Mercadante & Arcuri, 2007; Schmader, et al., 2010). For neuropathic pain, antiepileptics are currently the first line medications. Other medications helpful for neuropathic pain include TCAs, SNRIs, opioids, capsaicin cream, and lidocaine patches.
Steps 2 and 3, Opioid analgesics +/- non-opioid analgesics +/- adjuvants
As a rule, in elderly patients opioid analgesics should be started at the lowest effective dose and titrated slowly and carefully. Patients with continuous pain may be started on a low dose of scheduled short-acting opioid medication. The total daily opioid dose can then be increased by 30-50% every 24 hours if indicated. For patients with chronic pain, a long-acting opioid medication can be initiated after the pain is better controlled; the dose of the long-acting opioid should be based on the total daily dose the patient required of the short-acting opioid. Adding a long-acting medication increases compliance, since fewer scheduled doses are required. Breakthrough pain episodes in patients taking a long-acting opioid chronically can be treated with short-acting opioids. A typical breakthrough pain dose is recommended to be 5-15% of the total daily opioid dose (Zeppetella, 2011).
Notably, cognitive function may be noticeably impaired for up to a week following opioid dose escalations (Pergolizzi, et al., 2008). Furthermore, both physicians and nurses may misinterpret agitated delirium as pain in patients whose pain was well under control before and after the episode of delirium. In these patients, opioid escalation could be detrimental and worsen the patient's cognitive dysfunction (Yennurajalingam, Braiteh, & Bruera, 2005).
When switching from one opioid to another, a published equianalgesic ratio should be applied. The total dose of the new medication should then be reduced by 25-50% in order to account for incomplete cross-tolerance, (Yennurajalingam, Braiteh, & Bruera, 2005) since tolerance to the previous opioid does not confer the same degree of tolerance to a different one. For elderly or cognitively impaired patients, some experts recommend to reduce the dose even further by an additional 15-30% (Rastogi & Meek, 2013).
Concern for addiction is often cited as a reason for not initiating opioid medications. Patients with legitimate pain may limit their own opioid usage, fearing the stigma of addiction. There is a common misconception that the physical dependence often seen with opioid usage is a sign of addiction; however, true addiction is a syndrome characterized by psychological dependence—a craving for the drug—along with compulsive drug-seeking behaviors. True addiction is infrequent and perhaps even overestimated, as patients with undertreated pain may appear to be drug-seeking (Fallon, Cherny, & Hanks, 2011). Educating patients regarding the differences between physical dependence and addiction may increase medication compliance.
Codeine is dependent on conversion to morphine in the liver for analgesic efficacy; therefore, poor metabolizers—who constitute approximately 10% of the studied population—have correspondingly poor pain relief with codeine. (Mercadante & Arcuri, 2007)
Tramadol is also used to mild to moderate pain. In addition to its weak µ receptor activity, it also inhibits monoamine reuptake, which results in a risk of serotonin syndrome and increased seizure risk in the presence of other serotonergic medications. Its metabolism and elimination is dependent on the kidneys and liver, and elderly patients on tramadol should be monitored carefully. In the setting of renal insufficiency, doses of tramadol should not exceed 200 mg/day; for hepatic insufficiency, the dose is limited to no more than 50 mg every 12 hours.
The use of meperidine should be avoided in elderly patients, as normeperidine can rapidly accumulate and cause neurotoxicity, especially in the setting of renal insufficiency (Rastogi & Meek, 2013; Portenoy, 2012).
Hydrocodone is frequently combined with either NSAIDs or acetaminophen, and daily doses should be limited based on the NSAID or acetaminophen content.
Morphine is more likely than the other opioids—with the exception of codeine—to cause histamine release and itching (Portenoy, 2012). These are considered an adverse effect rather than a true allergy, since the histamine release is non-immune mediated. Morphine is metabolized to toxic metabolites in the liver, which are renally cleared. Morphine should be reduced and closely monitored or avoided in renal insufficiency (Fallon, Cherny, & Hanks, 2011).
Oxycodone is 30-50% more potent than morphine in studies. Oxymorphone is 3 times stronger than morphine in the oral form and 10 times stronger in intravenous form. Some studies suggest it may induce less histamine release than morphine (Fallon, Cherny, & Hanks, 2011). Hydromorphone is a strong opioid that is also converted to neurotoxic metabolites that accumulate in renal insufficiency; though it proportionally produces fewer toxins than morphine, close monitoring is still prudent (Johnson, 2007).
The fentanyl transdermal patch should be started at the 12mcg/h dose for opioid naïve patients (Portenoy, 2012). Notably, another analgesic should be provided when initiating the patch, as the patch generally takes 8-12 hours to reach effective analgesic levels. An additional consideration: fentanyl absorption via the patch increases with rising body temperature, and patients should be cautioned regarding hot baths and heating pad usage (Fallon, Cherny, & Hanks, 2011). Fentanyl does not have any active renally cleared metabolites and is one of the preferred opioids in renal insufficiency. Furthermore, fentanyl's pharmacokinetics are unchanged in hepatic insufficiency, and it may be the opioid of choice in hepatic insufficiency, as well (Bosilkovska, Walder, Besson, Daali, & Desmeules, 2012; Johnson, 2007).
Because of its long half-life, methadone requires close monitoring after dose adjustment. The plasma concentration of methadone continues to rise over a prolonged period of time, possibly resulting in delayed adverse effects (Portenoy, 2012; Fallon, Cherny, & Hanks, 2011). Since the potency of methadone increases with escalating doses, methadone management may be best left to pain specialists or other providers experienced in its use.
Lastly, it is very important to initiate laxative therapy when starting patients on opioid medications, as severe constipation can adversely affect the patient's quality of life by decreasing appetite as well as causing nausea and abdominal pain. If left untreated, it can eventually cause overflow diarrhea—often resulting in social withdrawal—and even delirium (Rastogi & Meek, 2013).
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