Background
Pain has been described as a more terrible lord of mankind than even death itself [
1]; nevertheless it is known that many people die with unnecessary pain [
2]. Musculoskeletal pain is a common symptom that is frequently under-reported and inadequately treated in older adults [
3], the stage of life when most people die [
4]. Musculoskeletal pain has the potential to impact on end of life care, especially as many of the first line strategies promoted, including exercise and self-management [
5] may not be applicable or appropriate as death approaches [
6]. The rationale driving this paper is that the most common cause of pain in older people [
7] may be being overlooked as it is rarely implicated as a cause of death, despite the potential for musculoskeletal disease to be a substantial cause of pain and discomfort in the dying person.
Musculoskeletal pain derives from a pathophysiologically diverse set of musculoskeletal conditions [
8] including osteoarthritis, rheumatoid arthritis and spinal trouble. It is commonly classified according to pain location (hip, knee, lower back) although most people with chronic pain have pain at multiple sites [
9]. One reason the topic has remained largely unexamined is that most studies of pain prevalence in the elderly are cross sectional and provide no information about the progression of pain with time [
7,
10]. Most studies of pain and other symptoms at the end of life consider the needs of people with a specific advancing progressive disease [
11‐
13], and do not include symptoms associated with co-morbid diseases like arthritis [
12], or other common causes of musculoskeletal pain. This is compounded by the dearth of research to inform the treatment of pain in the elderly [
5,
14]. A recent review of pain management found no well-designed studies of analgesia that specifically focused on elderly patients requiring palliative care [
15].
Another reason for the lack of research in this area may be that musculoskeletal pains are frequently considered to be part of the normal ‘wear and tear’ of aging [
5]. For instance, Klinkenberg et al [
16] compared the agreement between the reporting of symptoms and disease by elderly patients (n = 270) in research interviews, with proxy reporting in after-death interviews with significant others and after-death questionnaires completed by General Practitioners (GPs). Osteoarthritis (OA) was the chronic disease with the lowest concordance between both patient and proxy report and between patient and GP report, with patients reporting much higher prevalence in both comparisons. Klinkenberg et al [
16] suggested that the reason for the poor concordance was that healthcare professionals and significant others were more likely to recall the illness that led to death than a chronic disease that was integrated into a patients daily life.
The prevalence of musculoskeletal pain is known to increase with age until it stabilises around age 65 [
17]. However, the prevalence of disabling pain that impacts on life increases notably among older people into the oldest age-groups [
18]. The impact on individuals can be significant [
3]. A review of chronic pain prevalence in older people found estimates ranging from 18-57% [
19]. The wide range was partly explained by the variation in definitions used for chronic pain [
19]. There is less precise information about the prevalence, impact or treatment of musculoskeletal pain at the end of life. Consequently it is possible that a major cause of pain is being overlooked and a potential target for improving quality of life is being ignored. The objective of this study was to conduct a systematic search of the literature with the aim of highlighting what is currently known about musculoskeletal pain in older adults at the end of life and the identification of priorities for future research.
Discussion
The findings present a dichotomy of methods and focus with two epidemiological papers that suggest that musculoskeletal symptoms have a substantial impact at the end of life in the general population and four cases studies showing that musculoskeletal pain can be a significant issue for individuals requiring unusually sophisticated pain control measures including temporary sedation, cordotomy, arthroplasty and very high dose opiates. No information was found about the way that musculoskeletal symptoms were assessed and treated in the general population. Despite this, the findings do give some indication of the prevalence, impact and treatment of musculoskeletal pain at the end of life.
Prevalence
The population based studies indicated that musculoskeletal pain is a common and significant issue at the end of life. Smith et al’s [
29] study, the first epidemiological study to look at pain at the end of life, draws attention to the fact that musculoskeletal disease may have as much, if not more, effect on whether a person dies in pain than the condition that is the cause of death. Unfortunately, Smith et al [
29] do not define what is mean by the term ‘arthritis’. This is important as prevalence estimates of musculoskeletal disease occurrence can vary considerably depending on the phenotype definition [
31]. Also 19% of Smith et al’s [
29] data was obtained by proxies who may have underreported musculoskeletal symptoms [
16].
Smith et al’s [
29] study used the time between interview and death to document a significant increase in pain prevalence in people with arthritis as death approached. The authors highlighted the limitations of using cross sectional data in this fashion. Despite this, the findings emphasise the need to be especially vigilant for pain in people with co-morbid musculoskeletal disease in the final months of life [
32]. Borgsteede et al [
30] supported this by showing that musculoskeletal symptoms were prevalent in at least 20% of patient-GP encounters during the last three months of life. This is higher than the 14% annual prevalence of GP consultations for musculoskeletal disease in the general population reported by Jordan et al [
33]. However, the studies were undertaken in different countries and used different systems for classifying consultation data making direct comparison difficult. Furthermore, Borgsteede et al [
30] gave no information about the nature or severity of the symptoms, nor does it discuss how, or whether, they were successfully managed in practice. Borgsteed et al [
30] suggested that their study may have underestimated the prevalence of musculoskeletal symptoms as GP’s were unlikely to register all the symptoms affecting patients at the end of life and the records represented the most important symptoms as perceived by the GPs, rather than documenting the patients perspective [
30]. Smith et al [
29] may also have a systematic bias underestimating the true prevalence of musculoskeletal pain. The health and retirement study excluded people living in institutions, and admission to care homes is commonly prompted by reduced physical functioning [
34].
Although both population based studies found musculoskeletal disease had a significant impact at the end of life, the prevalence of symptoms recorded varied significantly: 60% in Smith et al [
29] and 20% in Borgsteede et al [
30]. As Smith et al [
29] does not discuss how ‘arthritis’ was defined and Borgsteede et al [
30] do not discuss the nature of the musculoskeletal symptoms, comparison is difficult. The extent of the disparity is similar to that observed when estimates of musculoskeletal pain from population surveys are compared with estimates derived from coded primary care data, with surveys consistently suggesting that only a minority of people raise the issue of even severe musculoskeletal pain with their GP [
35]. Nevertheless the fact that these figures do not more closely correspond provides tentative initial support for the idea that musculoskeletal pain is common at the end of life, but underestimated as a cause of pain by healthcare professionals. However, an alternative explanation is that raising an issue in a GP consultation is a proxy for severity causing patients to request treatment. Even the lower figure of 20% prevalence suggests that large numbers of people may be significantly affected by musculoskeletal pain. Neither Borgsteede et al [
30] or Smith et al [
29] were specifically investigating musculoskeletal pain at the end of life and both papers reported that the levels of musculoskeletal pain were new findings that had not been highlighted in previous end of life care research. This emphasises the need for more population based epidemiological studies which specifically focus on musculoskeletal symptoms. This is discussed further below.
Impact
The four case studies clearly demonstrated that musculoskeletal pain can significantly impact on individuals in diverse ways emphasizing the needs for individualised assessment and treatment of musculoskeletal pain at the end of life. However, as three of these studies describe particularly complex situations it is not possible to extrapolate any information about the impact of musculoskeletal pain to the general population. However the importance of the case histories as illustration is that they highlight that rational treatment targeted at comorbid musculoskeletal pain is a potentially important component of all patients in pain nearing the end of life: they powerfully challenge the assumption that pain in this period should simply be attributed to the condition causing death without considering other concurrent explanations. Neither of the population based studies discussed the impact or treatment of musculoskeletal pain.
Treatment
Only one of the case studies, Katz et al [
26], argued that the treatment described; (total joint replacement), could offer a potent and systematic treatment strategy in the palliative care of patients with advancing progressive disease and concomitant musculoskeletal pain. There was a dearth of studies about the treatments for musculoskeletal pain at the end of life in a primary care setting. This is an important omission because, although most people die in a hospital setting, the majority of the last year of life is lived in the community, either at home or within a care home [
2,
36].
A possible reason for the lack of information about treatment is that either the standard tools advocated by palliative care, or the treatments advocated for chronic musculoskeletal pain, are effective. Palliative care promotes the use of the World Health Organisation cancer pain ladder [
28] for systematic and effective pain management. Although there have been some studies that consider the effectiveness of this tool for cancer pain [
37,
38], there appears to be no study that considers whether this is an effective way to manage musculoskeletal pain at the end of life. There are, indeed, significant limitations in the evidence base for the use of opioids in chronic musculoskeletal pain [
39‐
41] and the side effects of opiates meant they were ineffective in two of the case reports [
25,
27]. Furthermore, there are concerns regarding the use of opiates for short term incident or episodic pains [
42], like the breakthrough pain provoked by movement described by Greenstreet [
21].
The fact that Smith et al [
29] reported that the prevalence of pain was similar across the different categories of terminal illness but substantially greater for people with concomitant arthritis, alongside the substantial body of evidence that many older adults live with chronic pain associated with musculoskeletal disease [
3,
7] tentatively suggests that musculoskeletal pain is not being effectively treated at the end of life. Rather, it is being overlooked as a potentially common cause of pain whilst attention is focused on supporting symptoms associated with concurrent advancing progressive disease.
Conclusion
This systematic search of the literature suggests that musculoskeletal disease is an important issue that can significantly impact on pain in the elderly at the end of life. It highlights the high prevalence of musculoskeletal symptoms at the end of life and the need for frequent assessment of musculoskeletal pain as death approaches. However, it also draws attention to the dearth of literature regarding evidence based treatment for people dying with musculoskeletal pain. One reason for the previous oversight of this important topic may be that chronic disease that is assimilated into a patient’s daily life is less likely to be the focus of concern than a concomitant advancing progressive disease [
16]. Priorities for research include epidemiology studies of musculoskeletal pain at the end of life and its impact on individuals, together with qualitative research into patient priorities related to this topic and research designed to provide an evidence base for treatment at this time.
Acknowledgements
Thanks to Jo Jordan, Research Information Manager at the Primary Care and Health Sciences Research Institute, Keele University, who provided independent expert advice regarding the literature search process.
Funding
This study was funded by a Keele University, School of Nursing and Midwifery Post – doctoral fellowship
Competing interests
The authors declare that there are no conflicts of interest.
Authors’ contributions
AKL, SR, CM, PC & JM participated in the planning and design of the project. AKL and JM developed the search strategy. AKL performed the search. PC independently read papers to validate the inclusion criteria. AKL, SR, CM, PC and JM drafted the manuscript. All authors read and approved the final manuscript.