Fatigue is a subjective symptom in older people and people living with frailty. Fatigue reduces physical capacity and energy reserves resulting in tiredness that is disproportionate to the level of exertion.1 Fatigue is a multidimensional phenomenon with physical, mental/cognitive, emotional and psychological manifestations.1-3
Older people with fatigue describe it as an ‘overwhelming’ feeling that is not relieved by rest.1 Fatigue can be acute (often linked to or part of a specific disease) or chronic (persisting for more than six months).3 Although fatigue is common in older adults, ranging in prevalence from 27-50%,1 healthcare professionals do not appear to know this.
The mechanisms of fatigue are not well understood and there is a lack of an objective or gold-standard assessment tool to diagnose fatigue in older people. Frailty and fatigue increase the risk of adverse outcomes like disability, loss of independence, hospitalisations and mortality.3-4 Fatigue is included in 49.4% of frailty assessment tools and scales including the Fried frailty model and Rockwood Frailty Index.5-7 Improving our knowledge of fatigue can help improve the outcomes for older adults who live with fatigue and/or frailty.
Further reading: The productivity of Comprehensive Geriatric Assessment
Further reading: Confusion in the older patient: a diagnostic approach
This meta-review aims to summarise the current knowledge of chronic fatigue in older people (over 65s) using review papers. In addition, the relationship between fatigue and frailty will also be explored
Three databases were searched including PubMed, Scopus and Ovid Medline. Keywords like fatigue, older people and frailty and their synonyms were searched. In addition, terms relating to the Fried frailty phenotype and their synonyms were also included (e.g. sarcopenia, weakness, exhaustion, slowness).
Inclusion criteria: Only reviews and systematic reviews that were published in the last 10 years (2009-2019), in English and focusing on older people (over 65s) were included.
Exclusion criteria: Reviews focusing on disease-specific fatigue (e.g. cancer related fatigue) and those looking at fatigue in people younger than 65 were excluded. Papers were excluded based on their title and abstracts.
An example of a search carried out on PubMed is shown below:
PUBMED search (17/04/2019):
(Fatigue OR lethargy OR lassitude OR tiredness OR exhaustion OR overtiredness OR “lack of energy” OR languidness OR languor OR listlessness) AND ((((elderly OR older OR ageing OR retired OR old OR geriatric) AND (patient OR person OR individual* OR adult OR senior)) OR senior OR pensioner) OR (Frailty OR pre-frailty OR “no frailty” OR “physical frailty” OR frailties OR frailness OR “frailty syndrome” OR “frailty phenotype” OR “non-frail” OR “nonfrail” OR “frail elderly” OR prefrail OR pre-frail OR ) OR (Fatigability OR (Sarcopenia OR “muscle wastage” OR “loss of muscle” OR “muscle atrophy” OR “muscle weakness” OR “muscular weakness”) OR Weakness OR slowness OR “walking speed” OR “low physical activity" OR “no physical activity" OR inactivity OR “physical inactivity” OR “mobility impairment” OR “grip strength” OR “weight loss” OR “thinness” OR “weight reduction”)) NOT (diabetes OR pregnancy OR stroke OR Parkinson’s OR fibromyalgia OR cancer OR sport OR young OR nutrition OR "heart failure" OR hypertension OR vaccine)
What is fatigue?
Fatigue in older people is a self-reported symptom. Currently, there is a lack of consensus on the definition of fatigue due to its subjective nature. Fatigue reduces physical capacity and energy reserves, is disproportionate to the level of activity and not relieved by rest.1
Older people used words such as “feeling incompetent”, “fading”, “heavy feeling” and “organs slowing down” to describe the fatigue symptom.1,8 Fatigue has been described as a continuum with tiredness representing the mildest form that can be relieved by rest and exhaustion representing the most severe form.1 Despite the distinction, fatigue, tiredness and exhaustion are used interchangeably in the literature.8 Other terms used include lethargy, languidness, languor, lassitude, ennui, faintness and listlessness.2,3
Classification of fatigue
Fatigue is a multidimensional phenomenon consisting of physical, cognitive, emotional and psychological aspects that may overlap. Fatigue can be classified and divided in many ways. Fatigue can be acute or chronic. Acute fatigue is often linked to or caused by a single specific disease, has a sudden onset and short duration. Resting and treatment of the underlying disease may alleviate acute fatigue.3 Chronic fatigue has multiple aetiologies, is persistent (lasting for six or more consecutive months) and is not alleviated by rest, diet or stress management.3
A review published in Nature magazine about fatigue in the context of neurological diseases, fatigue is classed as being primary, secondary or comorbid fatigue.2 Primary fatigue is fatigue due to neurological diseases independently of other chronic conditions.2 Secondary fatigue is caused by having multiple chronic conditions (other than neurological diseases) e.g. anaemia, thyroid dysfunction, psychiatric disorders, depression.2 Comorbid fatigue is described as fatigue occurring alongside primary diseases but not causally related to it or other chronic conditions.2
It is important to note that this classification is in the context of neurological diseases (e.g. Multiple Sclerosis, Stroke, Parkinson’s disease, Myasthenia Gravis) and that the difference between comorbid fatigue and secondary fatigue is not very clear. The author also confirms this as well as stating that multiple types of fatigue may be present in any one individual experiencing fatigue.
The review also proposes a taxonomy for classifying the manifestations of fatigue. Although this is described in the context of neurological diseases, the taxonomy appears relevant to the fatigue experience in older people. Future studies could look to confirm this.
This taxonomy divides fatigue experiences into objectively measurable performance deficit (performance fatigability) and the subjective perception of fatigue.2 Performance fatiguability can affect motor or cognitive tasks. Performance fatiguability can be caused by peripheral defects (conditions affecting Peripheral Nervous system) or central defects (conditions affecting Central Nervous system). Self-perceived fatigue can be due to homeostatic factors (e.g. hypothalamic dysfunction, defective central regulation of physical activity) or psychological factors. The psychological manifestations of fatigue can include poor concentration, reduced memory and attention, reduced motivation to work, poorer coping ability, increased irritability and diminished social function.1
When discussing fatigue, it is important to distinguish between fatigue and fatigability. Fatigability is defined as “the relationship between an individual’s perceived fatigue and the activity level with which the fatigue is associated”.9 Fatigability increases with age and increased fatigability means an individual will feel more tired by a defined activity compared to an individual with less fatigability.9 When studying fatigue prevalence, it is important to consider fatigability. For example, some older people may not report much fatigue however this may be due to them reducing physical activity in order to compensate for their increased fatigability.
There are various fatigue assessment tools however there is no standardised assessment tool. Some examples of assessment tools include the Brief Fatigue Inventory (BFI),10 Multidimensional Fatigue Inventory (MFI-20),11 Patient-Reported Outcome Measurement System (PROMIS),12 Avlund Mob-T Scale and Lower-Limb-T Scale,13 Pittsburgh Fatigability scale,14 Revised Piper fatigue scale,15 and SF-36 Vitality scale.13
BFI, Avlund Mob-T Scale, Avlund Lower-Limb-T Scale and SF-36 vitality scale have been validated for use in older people. Both BFI and MFI-20 were developed originally for use in cancer patients. BFI can provide information about the severity of fatigue. Opinion is divided as to whether BFI also provides information on fatigue interference.3,16 MFI is a 20-item multidimensional tool that can identify physical fatigue, mental fatigue, reduced motivation and reduced activity.17 Pittsburgh fatigability scale has been validated for use in older people and incorporates the fatigability concept.14 A review detailing the available fatigue/fatigability scales and their validity for use in older people would be helpful.
There is variation between different fatigue prevalence estimates. It can range from 27-50% of community dwelling older adults.1 The prevalence in a population of older people living in long-term care was higher at 98%.15 Despite this, there are also some studies which only report a prevalence of 8% as well as others that did not find an age-related increase in the prevalence of fatigue.3,8 This variation in prevalence estimates could be because fatigability was not considered in the studies that did not find an age-related increase in fatigue.3
As fatigability increases, older people may reduce their activity level to reduce feeling fatigued. In this case, the individual may report less or no fatigue but investigating their physical capacity and activity level may highlight that they are in fact experiencing fatigue. The variation in prevalence estimates could also be due to different definitions being used in different studies or a lack of a universal fatigue assessment. Risk factors for fatigue according to current knowledge include having multiple chronic conditions, poor functional performance, anxious personality, and a presence of psychological disorder.1
Effects of fatigue on quality of life and health outcomes
Fatigue has a negative impact on quality of life. Fatigue can be an overwhelming experience impacting the physical, emotional and social aspects of an individual. It can leave people feeling frustrated, incompetent, in despair and feel like a burden to others. Fatigue can prevent individuals from carrying out their usual activities of daily living resulting in a package of care support to be provided. Coping strategies used by older people included pacing of activities, eating sugary food and attending exercise classes.1
In a study looking at 10 community dwelling older people showed people tend to take regular breaks from activities throughout the day.8 Having periods of rest, sleeping or relaxation resulted in less tiredness, however importantly resting did not provide a permanent relief. It would be interesting for future studies on fatigue to confirm this aspect of whether resting helps with the fatigue symptom and the extent to which it does help.
Apart from reducing quality of life, other negative outcomes of fatigue include increased risk of disability, home-help utilization, hospitalizations and mortality. Older people who develop fatigue are at higher risk of developing a mobility impairment within 1.5 years,1 dependence on home-help and hospital services within 5 years and doubles the risk of mortality in the next 10 years.1
Frailty and fatigue
Frailty syndrome represents a decline in function and wellbeing that leaves individuals more vulnerable to negative health outcomes including falls, hospitalisations, disability and mortality.18 Its prevalence is higher in those aged 65 or over, in women and in African Americans.4 Frailty can be defined by the Fried frailty phenotype or by the Rockwood deficit accumulation model.5,7
The cumulative deficit model of frailty considers symptoms, diseases, conditions and disability. The frailty phenotype described by Fried includes weight loss, fatigue and exhaustion, weakness, slowness and low physical activity and mobility impairment.7 Individuals can be non-frail, pre-frail and frail. In the Fried phenotype, Non-frail individuals have none of the characteristics that make up the frailty phenotype, Pre-frail individuals have 1 or 2 characteristics and frail individuals can have three or more.18
Fatigue is part of the criteria in diagnosing frailty with the Fried model and hence has potential to be used as an early marker for frailty. A recent longitudinal study looking at transition rates between different frailty categories found that reversal of frailty status is possible.19
This shows that frailty is not to be considered an irreversible process and potential markers of frailty like fatigue should be explored further. This could help guide clinicians about the management of frailty. A longitudinal study following community dwelling women for 7.5 years and their onset of frailty, showed that weakness was the most common initial manifestation of the frailty phenotype.20 When weight loss and exhaustion were the initial manifestations of frailty, they represented a higher risk and rate of onset of frailty.20
More studies investigation the sequence of frailty manifestations and the place of fatigue in the sequence can clarify the usefulness of fatigue as a screening marker for fatigue.
Our understanding of the underlying pathophysiological mechanisms of fatigue could be improved. The suboptimal understanding and attention given to fatigue means fatigue assessment, diagnosis and management are not the best it could be. Currently there is no consensus on a universal definition for fatigue. There is also a lack of a “gold standard” fatigue assessment. The variance in definitions and assessments affects the accurate assessment of fatigue symptom and so diagnosis is made difficult.
Although fatigue is common among older people, it is often ignored or not given appropriate attention. This could be due to its vague subjective nature and/or the concept that fatigue is a normal part of ageing with no need for treatment. This attitude could also prevent older people from reporting it during routine clinical assessment. Fatigue is not given the same amount of attention and interest as pain and depression that are also common among older people. Fatigue should be included in routine clinical assessments of older people in the same way as pain and depression.
Healthcare professionals need to take an active role in assessing fatigue in older people and acknowledge that fatigue can be debilitating and detrimental to a persons’ quality of life. Once a diagnosis has been made, treatment options are also an area where much improvement is needed. There is a lack of research-based evidence for fatigue management.1 Currently treatment options are based on the underlying causes. In the absence of a clear cause, fatigue may be left untreated.3
Fatigue prevalence estimates vary widely among different studies. Developing a standardized tool and definition for assessing fatigue could help to produce more consistent findings. Considering fatigability is important to produce reliable fatigue prevalence estimates. A clear and concise definition of fatigue does not exist. This could be due to fatigue having multiple aetiologies and manifestations, as well as it being a subjective symptom. Efforts should be made to identify the clinical manifestations of fatigue and how they differ according to severity of fatigue.
This could help healthcare professionals better identify fatigue in older people. In addition, developing knowledge of the underlying pathophysiology of fatigue using animal and human models will also be useful.21 Cross-sectional studies looking at the prevalence of fatigue in frail, pre-frail and non-frail individuals can improve our understanding about the relationship between fatigue and frailty. More longitudinal studies exploring the prevalence of fatigue in different frailty profiles should be carried out.
Healthcare professionals should take an active role in assessing fatigue especially those with risk factors (having multiple chronic conditions, comorbidity, poor functional performance, higher trait anxiety and/or a presence of psychological disorders). Currently, most interventions for fatigue are based on the underlying illness or cause of the fatigue, however if no cause is found, then fatigue is often left undertreated. A comprehensive holistic assessment provides a detailed and holistic picture of a person’s health and so could help identify the factors responsible for fatigue in older people- especially when there is no specific cause.3 Physical capacity of older people with fatigue needs to be improved as reduced physical capacity can cause muscle wasting further increasing the fatigue symptom.
Persistent fatigue is a self-reported symptom common in older people. Risk factors associated with fatigue include having multiple chronic conditions, poor functional performance, anxious personality, and the presence of a psychological disorder. Fatigue is associated with adverse outcomes such as disability, hospitalisations and requiring assistance with activities of daily living. In addition, fatigue decreases quality of life by limiting older people’s ability to engage and participate in their usual activities including social events.
Older people use pacing and reducing their activity level as a coping strategy. Reduced physical capacity can lead to a sedentary lifestyle that worsens fatigue, so it is important to encourage exercise and physical activity in older people. Living with fatigue can be burdensome for the individual and so it is important that healthcare professionals and researchers give the fatigue symptom adequate consideration.
- Fatigue is a multidimensional phenomenon with physical, mental and psychological manifestations
- Fatigue is associated with adverse outcomes such as disability, hospitalisations and requiring assistance with activities of daily living
- Healthcare professionals and researchers need to give the fatigue symptom adequate consideration
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Sana Latheef Kalathil, University of Liverpool, School of Medicine
Asangaedem Akpan MPH FRCP Consultant Geriatrician & Honorary Clinical Associate Professor, Medicine for Older People and Stroke, Liverpool University Hospitals NHS FT & Institute of Life Course & Medical Sciences, University of Liverpool
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- Penner IK, Paul F. Fatigue as a symptom or comorbidity of neurological diseases. Nature reviews Neurology 2017;13(11):662-75. doi:10.1038/nrneurol.2017.117 [published Online First: 2017/10/14]
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- Knoop V, Costenoble A, Vella Azzopardi R, et al. The operationalization of fatigue in frailty scales: a systematic review. Ageing research reviews 2019;53:100911. doi:https://doi.org/10.1016/j.arr.2019.100911
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- Parse RR. The lived experience of feeling very tired: a study using the Parse research method. Nursing Science Quarterly 2003;16(4):319-25.
- Eldadah BA. Fatigue and fatigability in older adults. PM & R : the journal of injury, function, and rehabilitation 2010;2(5):406-13. doi:10.1016/j.pmrj.2010.03.022 [published Online First: 2010/07/27]
- Mendoza TR, Wang XS, Cleeland CS, et al. The rapid assessment of fatigue severity in cancer patients: use of the Brief Fatigue Inventory. Cancer 1999;85(5):1186-96.
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- Christodoulou C, Schneider S, Junghaenel DU, et al. Measuring daily fatigue using a brief scale adapted from the Patient-Reported Outcomes Measurement Information System (PROMIS®). Quality of Life Research 2014;23(4):1245-53.
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