Chapter 19
Pain in the elderly
The epidemiology of pain across the lifespan
Age differences in pain as a presenting symptom of clinical disease
Summary of epidemiologic studies on age differences in pain
Epidemiology of pain in special older populations
Explaining age differences in pain prevalence and report
Age differences in psychosocial aspects of pain
Age-related changes in neurophysiology
Age differences in pain processing under pathophysiologic conditions
Pain processing in persons with dementia
Managing pain in older persons
At the end of this chapter readers will have an understanding of:
1 How the pain experience differs with age.
2 Particular conditions that commonly cause pain among middle-aged and older people.
3 Differences in pain report and coping strategies among people of different age groups.
4 How age-related changes in neurophysiology may alter the pain experience.
5 How the pain experience is unique for older people in special populations, such as those with dementia.
6 How to approach the assessment of pain in elderly persons.
OVERVIEW
Throughout the world there has been an increase in the number of people living into old age. Throughout the world the number of people aged over 60 years is anticipated to triple by 2050, and the number over 80 years of age is expected to increase by more than five-fold (Australian Bureau of Statistics 2004). This is relevant for many nations, including Australia, Japan, Korea and the USA. For example, in Korea an escalation of the number of older persons is expected, with older adults expected to increase from 7.2% to 14.3% of the total Korean population by 2018 (Park et al 2009). In the USA it is expected that the population aged 65 and above will double by 2050 (US Census Bureau DIS 2012).
THE EPIDEMIOLOGY OF PAIN ACROSS THE LIFESPAN
Recent reviews of the epidemiologic literature reveal a marked age-related increase in the prevalence of persistent pain (often defined as pain on most days persisting beyond 3 months) up until the seventh decade of life and then either a plateau or slight decline into very advanced age (Helme & Gibson 2001; McBeth & Jones 2007). In contrast, the prevalence of acute pain in the community appears to remain relatively constant at approximately 5% regardless of age (Crook et al 1984; Kendig et al 1996). Absolute prevalence rates of persistent pain vary widely between different studies (7–80%) and depend upon the time interval sampled (days, weeks, months, lifetime), the time in pain during this interval (pain everyday, most days, at least weekly, any pain during the period), the severity of pain needed for inclusion as a case (mild, moderate, bothersome, activity limiting, etc.) and the sampling technique (telephone, interview, questionnaire). Nonetheless, with one exception (Crook et al 1984), all studies show a progressive increase in pain prevalence throughout early adulthood (7–20%), with a peak prevalence during late middle age (50–65; 20–80%) followed by a plateau or decline in the ‘old’ old (75–85) and ‘oldest’ old (85 +) adults (25–60%) (Andersson et al 1993; Bassols et al 1999; Blyth et al 2001; Brattberg et al 1989, 1997; Herr et al 1991; Kendig et al 1996; Kind et al 1998; Magni et al 1993; Tsang et al 2008).
When considering pain at specific anatomical sites, a slightly different picture emerges. Foot and leg pain have been reported to increase with advancing age well into the ninth decade of life (Benvenuti et al 1995; Herr et al 1991; Leveille et al 1998). The prevalence of articular joint pain (particularly of weight-bearing joints) also doubles in adults over 65 years of age (Barberger-Gateau et al 1992; Bergman et al 2001; Harkins et al 1994; Sternbach 1986; Von Korff et al 1990). Conversely, the prevalence of headache (Andersson et al 1993; D’Alessandro et al 1988; Kay et al 1992; Sternbach 1986), abdominal pain (Kay et al 1992; Lavsky-Shulan et al 1985) and chest pain (Andersson et al 1993; Sternbach 1986; Tibblin et al 1990; Von Korff et al 1988) all peak during later middle age (45–55) and decline thereafter. Oral pain may not change in prevalence over the lifespan (Leung et al 2008). Studies of age-specific rates of back pain are mixed, with some reports of a progressive increase over the lifespan (Dionne et al 2006; Harkins et al 1994; Von Korff et al 1988) and others of a reverse trend after a peak prevalence at 40–50 years (Andersson et al 1993; Borenstein 2001; Sternbach 1986; Tibblin et al 1990). While the site of pain does seem to influence the age-related pattern of pain prevalence, with the exception of joint pain, a consensus view from these studies would still support the notion of peak pain prevalence in late middle age and then a decline in persistent pain into very advanced age.
The very high prevalence of pain noted in older segments of the community has clear resource implications for the provision of pain management, but it is important to understand that not all persistent pain will be bothersome or of high impact. Indeed, many older persons will not seek treatment for pain and will manage pain symptoms without help. For this reason, several recent studies have started to focus on pain termed as ‘clinically relevant’ or ‘clinically significant’. Large epidemiologic surveys show that approximately 14% of adults over 60 years suffer from moderate-severe or significant pain, defined as continuous, needing professional treatment and occurring on most days in the past 3 months (Breivik et al 2006; Smith et al 2001). Adults aged 75 + have been found to be four times more likely to suffer from a significant pain problem than young adults. Similarly, 15% of residents in nursing homes have moderate-severe pain and almost half of these have been judged to have inadequate pain management (Teno et al 2003). It appears, therefore, that ‘clinically relevant’ pain also shows a major age-related increase in prevalence, and that older segments of the community are in most need of state-of-the-art treatment services for the management of bothersome pain.
AGE DIFFERENCES IN PAIN AS A PRESENTING SYMPTOM OF CLINICAL DISEASE
Another source of information on age-related changes in the pain experience can be derived from the patterns of symptom presentation in those clinical disease states that are known to have pain as a usual component (Gibson & Helme 2001; Pickering 2005). The majority of studies in this area have focused on somatic or visceral pain complaints and particularly myocardial pain, abdominal pain associated with acute infection and different forms of malignancy. Variations in the classic presentations of ‘crushing’ myocardial pain in the chest, left arm and jaw are known to be much more common in older adults. Indeed, approximately 35–42% of adults over the age of 65 years experience apparently silent or painless heart attack (Konu 1977; MacDonald et al 1983). For many patients with coronary artery disease, strenuous physical exercise will induce myocardial ischaemia as indexed by a 1 mm drop in the ST segment of the electrocardiogram. By comparing the onset and degree of exertion-induced ischaemia with subjective pain report, it is possible to provide an experimentally controlled evaluation of myocardial pain across the adult lifespan. Several studies have documented a significant age-related delay between the onset of ischaemia and the report of chest pain (Ambepitiya et al 1993, 1994; Miller et al 1990; Rittger et al 2010). Adults over 70 years take almost three times as long as young adults to first report the presence of pain (Ambepitiya et al 1993, 1994; Rittger et al 2010). Moreover, the severity of pain report is reduced even after controlling for variations in the extent of ischaemia. Collectively, these findings provide strong support for the view that myocardial pain may be somewhat muted in adults of advanced age.
With regard to pain associated with various types of malignancy, a retrospective review of more than 1500 cases revealed a marked difference in the incidence of pain between younger adults (55% with pain), middle-aged adults (35% with pain) and older adults (26% with pain) (Cherng et al 1991). With one exception (Vigano et al 1998), most studies also note a significant decline in the intensity of cancer pain symptoms in adults of advanced age (70 + years) (Brescia et al 1992; Caraceni & Portenoy 1999; McMillan 1989). The presentation of clinical pain associated with abdominal complaints such as peritonitis, peptic ulcer and intestinal obstruction shows a similar pattern of age-related change. Pain symptoms become more occult after the age of 80 years and, in marked contrast to young adults, the collection of clinical symptoms (nausea, fever, tachycardia) with the highest diagnostic accuracy does not even include abdominal pain. (Albano et al 1975; Wroblewski & Mikulowski 1991). From these uncontrolled studies, it is difficult to ascertain whether the apparent decline in pain reflects some age difference in disease severity and/or the willingness to report pain as a symptom, or whether it reflects an actual age-related change in the pain experience itself.
Other reports of atypical pain presentation have been documented for pneumonia, pneumothorax and post-operative pain. For instance, several studies suggest that older adults report a lower intensity of pain in the post-operative recovery period even after matching for the type of surgical procedure and the extent of tissue damage (Morrison et al 1998; Oberle et al 1990; Thomas et al 1998). This change is thought to be clinically significant and is in the order of a 10–20% reduction per decade after the age of 60 years (Morrison et al 1998; Thomas et al 1998). Older men undergoing prostatectomy reported less pain on a present pain intensity scale and McGill Pain Questionnaire (but not on a visual analogue scale) in the immediate post-operative period and used less patient-controlled opioid analgesia than younger men undergoing the same procedure (Gagliese & Katz 2003). Recent studies of chronic musculoskeletal pain have also started to address the issue of age differences. This is of considerable importance given that more than three-quarters of persistent pain states are of musculoskeletal origin. Unfortunately, the findings are quite equivocal, with reports of increased severity of arthritic pain in older adults (Chiou et al 2009; Harkins et al 1994), decreased pain severity (Lichtenberg et al 1984; Parker et al 1988) and no change (Gagliese & Melzack 1997; Yunus et al 1988). Some caution is needed when interpreting these findings, as the studies cited do not indicate that pain is reduced in older persons when it is actually reported. On the contrary, a report of pain is probably greater evidence of discomfort in older persons who do choose to report it and, even though pain symptoms may be more occult, the demonstrated age-related increase in disease prevalence (including in those cases mentioned above) suggests a corresponding increase in the prevalence of pain in older adults, at least until very advanced age.
EPIDEMIOLOGY OF PAIN IN SPECIAL OLDER POPULATIONS
Persistent pain is typically more common in institutional settings such as residential care facilities and nursing homes. Almost 5% of the older adult population will reside in nursing homes or long-term care settings in developed countries, and over half of these will suffer from cognitive impairment or dementia (Gibson 2007). As a result, it is important to characterize the epidemiology of pain in these special older populations. A number of studies demonstrate an exceptionally high prevalence of pain in residential aged care facilities, with as many as 58–83% of residents suffering from some persistent pain complaint (Ferrell 1995; Parmelee et al 1993; Weiner et al 1998). Using the minimum data set from all nursing homes in the USA (representing almost 2.2 million residents), approximately 15% of residents had ‘clinically significant’ pain of moderate or severe intensity and 3.7% had excruciating pain on at least one day in the previous week (Teno et al 2001, 2004).
There is some evidence to suggest a lower prevalence of pain in persons with cognitive impairment or dementia (Parmelee et al 1993; Proctor & Hirdes 2001; Walid & Zaytseva 2009). A significant inverse relationship between pain report and cognitive impairment has been shown in nursing home residents (Cohen-Mansfield & Marx 1993; Parmelee et al 1993). Both the prevalence and severity of pain were reduced in those with more severe cognitive impairment, and the magnitude of difference was quite large. For instance, pain was detected in just 31.5% of cognitively impaired residents, compared to 61% of cognitively intact residents, despite both groups being equally afflicted with potentially painful disease (Proctor & Hirdes 2001). Subsequent work has confirmed that the observed decrease in pain occurs when using either self-report pain assessment (Leong & Nuo 2007; Mäntyselkä et al 2004) or, with one exception (Feldt et al 1998), observational pain scales or proxy nurse ratings of a resident’s pain (Leong & Nuo 2007; Sawyer et al 2007; Wu et al 2005). Given the similar findings with both self-report and observational assessments, it might be deduced that the reduced levels of pain prevalence and intensity are not simply due to deterioration in verbal communication skills with advancing dementia. There is also reduced pain report in those with dementia following acute medical procedures, including venipuncture (Porter et al 1996) and injection (Defrin et al 2006), as well as a possible reduction in the prevalence of post-lumbar puncture headache (Blennow et al 1993). There have been relatively few studies to examine pain report in different subtypes of dementia, although patients with Alzheimer’s disease indicate a significant decrease in self-rated pain intensity and affect when compared to age-matched controls (Scherder et al 1999, 2001), and the reduction in self-reported or observational pain scores has not been found to differ according to dementia diagnosis (vascular, Alzheimer’s disease, mixed) (Husebo et al 2008; Mäntyselkä et al 2004).
EXPLAINING AGE DIFFERENCES IN PAIN PREVALENCE AND REPORT
The age-related increase in pain prevalence until late middle age is easy to explain given that the highest rates of surgery, injury and painful degenerative disease are found in the older segments of the population. However, the unexpected drop in pain prevalence during very advanced age is perhaps more difficult to understand, as the rates of injury and disease continue to climb over the entire adult lifespan. Indeed, several recent systematic reviews of the epidemiology of radiographic osteoarthritis demonstrate a continual and escalating rise in incident disease with advancing age (Arden & Nevitt 2006). Osteoarthritis of weight-bearing joints (hips, knees, feet) is present in the majority of individuals by age 65 years and affects more than 80% of persons over 75 years of age. This single entity could be expected to lead to a massive age-related increase in the presence of persistent pain. However, it is widely acknowledged that joints affected by osteoarthritis often remain asymptomatic (pain-free) despite the presence of radiographic change, and this apparent discordance between symptoms and disease (Hannan et al 2000) mirrors the situation of more occult pain symptoms in many other clinical conditions (see above). In explaining differences in pain perception and report one needs to consider age differences in the neurophysiological aspects underlying the experience of pain, and the role of psychological and social mediators of pain in older persons.
AGE DIFFERENCES IN PSYCHOSOCIAL ASPECTS OF PAIN
It has been suggested that older adults perceive pain as something to be expected and just a normal part of old age (Hofland 1992). With some exceptions (Gagliese & Melzack 1997; McCracken 1998), empirical studies of pain appraisals and ageing provide clear support for this view (Liddell & Locker 1997; Fahey et al 2008; Ruzicka 1998; Stoller 1993; Weiner & Rudy 2002) and the idea that older adults are often more accepting of mild pain symptoms (Appelt et al 2007; Gignac et al 2006). For instance, when compared to arthritis patients aged 50–59 years, adults aged greater than 70 years were 2.3 times more likely to agree with the statement that ‘arthritis is just a natural part of growing old’ and 5.2 times more likely to endorse the statement that ‘people should expect to have to live with pain as they grow old’ (Appelt et al 2007). This style of misattribution has important implications, as older people appear less threatened by mild pain symptoms and are less likely to seek treatment (Stoller 1993). However, this mistaken accreditation of pain symptoms to normal ageing only occurs for mild-moderate aches and pains. If pain is severe, older persons are more likely to interpret the experience as a sign of serious illness and are more likely to seek rapid medical care than their younger counterparts (Leventhal & Prohaska 1986; Stoller 1993).
Attention has also started to focus on age differences in other types of pain beliefs, such as stoicism, control over pain and beliefs in finding a cure. The conviction that organic issues are important in determining the pain experience have been reported as similar between younger and older chronic pain patients (Gagliese & Melzack 1997), although older patients may be less inclined to acknowledge that pain leads to emotional disturbance (Cook et al 1999). In addition, older adults appear to endorse a greater conviction in finding a medical cure for pain and have a lesser belief that persistent pain is disabling (Gibson 2003). The locus of control scale has been used to examine age differences in cognitive factors related to control over pain. Older chronic pain patients have a greater belief in pain severity being controlled by factors of chance or fate (Gibson & Helme 2000) when compared to younger pain patients, who seem more likely to endorse their own behaviours and actions as the strongest determinant of pain severity. Older patients with chronic pain also express more stoicism toward pain (Yong 2006; Yong et al 2001, 2003), with higher reported stoic-fortitude and a greater cautious self-doubt for pain report. This finding is consistent with other studies of stoic attitudes in older pain patients (Machin & Williams 1998) and provides strong empirical support for the widely held view that older cohorts are generally more stoic in response to pain.
In order to deal with the negative impacts of persistent pain on quality of life, patients often develop a variety of coping strategies. The self-perceived efficacy in being able to use coping methods to successfully manage pain does not appear to change with advancing age (Corran et al 1994; Gagliese et al 2000; Keefe & Williams 1990; Keefe et al 1991; Watkins et al 1999). The findings on age differences in coping strategies have somewhat mixed results. Studies by Keefe and colleagues have shown no age differences in the frequency of coping strategy use, although there was a strong trend for older adults to engage more with praying and hoping than young people (Keefe & Williams 1990; Keefe et al 1991). Conversely, older people with chronic pain have been found to report fewer cognitive coping strategies and an increased use of physical methods of pain control when compared to young adults (Sorkin et al 1990). Corran et al (1994) examined a large sample of outpatients attending a multidisciplinary pain treatment centre and found a significantly higher prevalence of praying and hoping as well as fewer incidences of ignoring pain in adults aged greater than 60 years. Watkins et al (1999) also reported clear age differences for patients in mild pain, with middle-aged and older adults reporting more catastrophizing, praying and hoping, but less frequent use of self-coping statements, than younger adults. Further research is needed to help document the extent and type of age differences in coping efforts and the exact circumstances under which this might occur.
