Abstract and Introduction
Acute pain management in the older adult is both challenging and rewarding. This review addresses the difficulty with assessment of pain in the older adult, variations in the pain experience of older adults, physiological differences between the young and old, changes in pharmacokinetics and pharmacodynamics with age, and useful pharmacological treatments for acute pain in older adults. It then presents a few representative cases of pain management in older adults. The goal of this review is to provide relevant information that can be used to manage acute postoperative pain in the older adult.
The United States Census Bureau predicts that the population of the USA will increase from 310 million in 2010 to 439 million by 2050. The baby boomer population (those born between 1946 and 1964) will begin to turn 65 years of age in 2011 and consequently the population of Americans who are 65 years old or older will grow from 13% in 2010 to 20.2% by 2050. In fact, centenarians will demonstrate a 437% growth in population over the next 40 years. In 2007, approximately 35% of surgical procedures were performed in patients 65 years and older. Approximately 42% of hospitalized older patients receive at least one procedure during admission, compared with only 10% in those less than 65 years of age.
Chronic health conditions, including chronic pain, are common in older adults. Chronic musculoskeletal pain from degenerative bone, joint and spine diseases is prevalent in the elderly population. Neuropathic pain, such as that experienced as a result of diabetic neuropathy, postherpetic neuralgia and poststroke or amputation pain is quite common. Chronic pain prevalence is estimated at 25–50% of community-dwelling older persons and probably up to 80% in elderly patients in nursing homes.[2–4] Approximately 22% of elderly Americans are affected by some type of cancer and up to 80% of cancer patients experience pain related to their disease or disease treatment. Persistent pain in the older adult has been associated with increased healthcare utilization, sleep disturbances, decreased socialization and impaired ambulation. Between 8 and 20% of older patients display depressive symptoms, and depression has been associated with worsened pain.
Treating acute and/or chronic pain in the older patient can be challenging. Older patients typically have more medical comorbidities than their younger counterparts. They also take more prescription medications; on average two to five medications per person. Drug interactions are common and polypharmacy, as defined by regular use of five or more medications, is estimated at 20–40% in older patients. Additionally, inappropriate prescribing of medications places the older patient at risk for adverse reactions and preventable hospitalizations.[8,9] Unfortunately, nearly 35% of medication trials exclude older patients based on age alone.[10,11] Therefore, the effect of aging on pharmacokinetics and pharmacodynamics of drugs is incompletely characterized.
The risk of postoperative delirium (POD) and postoperative cognitive decline (POCD) increases with age.[12,13] Hip fracture patients are at especially high risk of developing POD. Certain medications, such as tramadol, are associated with development of POD. Tramadol, while commonly used to treat acute and chronic pain in adults, will not be discussed further in this article as there is limited description of use in older adults in the literature. Please see the article by Lewis and Han for general information regarding tramadol. POD and POCD are also associated with preoperative cognitive impairment, vision impairment, depression and other common comorbidities, such as vascular disease and renal dysfunction. POCD is closely linked to delirium in the perioperative period, which is in turn related to acute pain and pain treatment, but risk for POCD may be independent of the type of anesthesia received.[17,18] Although it may be assumed that general anesthesia and complex surgery would result in an increased likelihood of POCD, a recent study challenges this assumption. In this study, patients who received procedural sedation had the same risk of cognitive decline as those undergoing elective total hip joint replacement surgery or coronary artery bypass surgery. POD and POCD worsen the clinician's ability to assess pain and may lead to inappropriate treatment. The unfortunate result of POD and POCD is decreased level of function and increased morbidity and mortality.
This article will attempt to describe the assessment of pain in older patients, as well as differences in the pain experience between the old and young. Physiological and pharmacological differences will be described. In addition, focus will be turned on medication management in the acute setting. Unfortunately, many medications have not been studied well in the older population. Nonpharmacological approaches to postoperative pain management will not be discussed, although this would be an interesting topic for further discussion.
Aging Health. 2011;7(6):813-828. © 2011 Future Medicine Ltd.