Prevalence of Fatigue and Perceived Fatigability in Older Adults: A Systematic Review and Meta-analysis

doi:10.21203/rs.3.rs-4796300/v1

Fatigue is a common health complaint in older adults, but its prevalence varies widely among studies due to differences in populations and assessment tools. The object of this review is to systematically evaluate the prevalence of fatigue and perceived fatigability in older adults. Four major public databases (PubMed, Embase, Web of Science (WoS), and Cochran Library) were searched for eligible studies on the prevalence of fatigue and perceived fatigability in older adults from January 1, 2000 to December 27, 2023. Cochrane Q tests and the I² statistic were used to assess between-study heterogeneity via Stata16.0. A total of 21 studies involving 17843 participants were included in this study. The prevalence of fatigue in older adults was 42.6%, and the prevalence of perceived physical fatigability and mental fatigability was 58.2% and 24.0%. Meta-analysis showed that the prevalence of perceived physical fatigability among older adults was very high, which varied with regional economic development level, age of the subjects, sample size and representativeness of the subjects. Fatigue is a health dilemma faced by most older adults. To improve quality of life, early and regular fatigue assessment should be part of routine health screening for older adults.

Health sciences/Health care

Health sciences/Medical research

Fatigue

Frail Elderly

Meta-analysis

Prevalence

Systematic review

Fatigue is defined as a subjective feeling of weakness, lack of energy, and tiredness¹; ². Due to a series of functional decline associated with aging, fatigue has become a common complaint in older adults and has a serious impact on their quality of life³; ⁴. Previous studies have shown that fatigue is associated with a variety of negative health outcomes in older adults, such as reduced quality of life, functional limitation, disability, hospitalization, and death^5-7. The population aged 60 years and older is projected to increase to 1.4 billion by 2030 and 2.1 billion by 2050, based on WHO data⁸. As the world's population ages rapidly, the negative health consequences associated with fatigue pose a serious challenge to the care of older adults. Therefore, in the context of aging, attention to the status of fatigue has important health implications in older adults^9-11.

The lack of an overall understanding of the prevalence of fatigue in older adults is a matter of great concern for several reasons. First, fatigue may be similar to pain in older adults, as both symptoms can act as physiological warning signs¹². Clinically, most health care providers focus on the specific disease rather than fatigue because fatigue is often a concomitant symptom of other conditions. Second, as a subjective state of description, fatigue has specificity in older adults¹³. Different people may rate their level of fatigue at the same level, but the effect of similar ratings of fatigue levels on physical activity may vary from person to person¹⁴. Third, when experiencing fatigue, some older adults regard it as a normal phenomenon of aging¹⁵. Fatigue describes the perceived state of an individual, and fatigability can convey functional information about an individual¹². Unlike fatigue, fatigability is a phenotypic trait determined by the relationship between self-reported fatigue and fatigue-related activity levels¹⁶. Fatigability allows us to characterize individual susceptibility to fatigue in the context of quantifiable demands of fixed intensity and duration¹⁷. For example, when two people report the same level of fatigue in the past week, one is active with near-normal functional abilities, and the other is sedentary with impairments in several functional abilities. Although both experienced the same fatigue over the past week, the intensity and duration of their activities during the same period were quite different¹². Therefore, it can be explained that the latter has a higher fatiguability compared to the former. Routine assessment of fatigue and fatigability may help to identify older adults who are vulnerable to a greater than expected decline in function¹⁸. In other words, timely assessment and identification of fatigue dimensions will play an early warning role in health care work, avoid health risks, and improve the quality of life among older adults.

Previous studies have shown that self-report tools with clear cutoff values for scale can be used to assess fatigue and fatigability in older adults and help us identify those at risk for activity limitation^19-21. Currently, there are many studies on the prevalence of fatigue and fatigability in older adults around the world. The prevalence of fatigue and fatigability varied from 8.88%-88.18% in older adults²²; ²³. The data of these studies were collected from different populations in different countries or regions and used different assessment tools. For example, some fatigue measurement scales are a unidimensional construct, while others specify different quality dimensions of fatigue, such as physical fatigability and mental fatigability²¹. Given the important role of various measurement scales in identifying and quantifying fatigue and fatigability, clarifying assessment tools for different dimensions of fatigue measurement may provide more accurate data for the assessment and classified management of fatigue in older adults²⁴. Second, most data on the prevalence of fatigue come from populations with other clinically diagnosed conditions, such as chronic fatigue syndrome/myalgic encephalomyelitis (CFS/ME), post-stroke fatigue, Parkinson's disease fatigue, and diabetes fatigue^25-29. Therefore, in addition to identifying the different dimensions of fatigue in older adults without other clinical diagnoses, this study will analyze the differences in the prevalence of fatigue in different subgroups (including gender, age and socioeconomic factors, etc.) in detail to provide epidemiological evidence for specific intervention measures for high-risk groups.

Search Strategy and Identification of Studies

The Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines were adopted for this systematic review and meta-analysis³⁰. This review has been approved for registration by Prospero (registration number CRD42023495515). Four electronic databases (PubMed, Embase, Web of Science (WoS), and Cochran Library) were searched independently for epidemiological literature on fatigue from January 1, 2000 to December 27, 2023 by two authors (TH and ZX). The computer-based searches combined fatigue and elder related terms and also searched other literature such as government reports, conference proceedings, and papers for additional data. No restrictions on dates or languages were applied during the search, and Boolean terms were used to maximize the search results to ensure that all relevant articles were retrieved. The full details of the search strategy are provided in the online supplementary Materials (eMethods 1).

Inclusion and Exclusion Criteria

Studies were included in this review according to the following inclusion criteria: (a) The data included in this study were from studies published in peer-reviewed journals that had been approved by the relevant ethical review bodies; (b)Fatigue in older adults is well defined and a validated fatigue or fatigability measurement tool is used; (c)Prevalence of fatigue and fatigability in older adults were accurately and clearly reported either in percentages or in numbers sufficient for calculating the percentages; (d) Participants investigated were all aged 60 or above; (e)For multiple articles using data from the same population, we selected the one with the highest literature quality score.

By contrast, studies were not reviewed if they met any of four exclusion criteria: (a)These are reviews, case reports, letters or editorials; (b)Specific study populations were used, such as patients with specific diseases (such as cancer, stroke, and AIDS) or people who were fatigued due to intense work or exercise; (c)Studies that specifically refer to different mental disorders or other comorbidities; (d)No studies with complete data reporting on fatigue prevalence were available even through online databases, library requests, or email correspondence with authors.

Data Extraction and Quality Assessment

Data from each study included in the review were extracted independently by the two main authors (TH and ZX) and cross-validated using a standardized scale. Information extracted for each study included: author information, year of publication, country, sample size, participant (mean) age, number and percentage of male participants, assessment instrument, outcome definition (i.e., cut-off point for specific assessment instrument), and prevalence of fatigue. All differences were resolved by examination and adjudication by the corresponding author (FY). Authors who participated in data extraction for each study included in this review were trained in standardized library data retrieval strategies.

The quality of each study ultimately included was assessed using a modified version of the Newcastle-Ottawa Scale (NOS)³¹. The NOS scale was evaluated for sample representativeness, sample size, response rate, determination of fatigue, and quality of descriptive statistical reports (eMethods 1). With a score of 0 or 1 for each dimension, studies were judged to have a low risk of bias (total score ≥3 points) or a high risk of bias (total score <3 points). Complete details of the quality score for each included study are provided in eTable 1 in the Supplementary material. The table was generated by consensus among the three authors.

Statistical Analysis

Prevalence estimates of fatigue and fatigability were calculated by aggregating study-specific estimates using a random-effects meta-analysis that accounted for between-study heterogeneity³². When fatigue prevalence estimates for different periods were reported in the included longitudinal studies, the overall prevalence for the entire period was used. Cochrane Q tests and the I² statistic were used to assess between-study heterogeneity. For the Cochrane Q test, p <0.05 represented significant heterogeneity. For I² index, values ≥75% indicating considerable heterogeneity³³; ³⁴.

We performed a subgroup analysis of perceived physical fatigability and mental fatigability. Stratification analysis was layered for gender, regional economic level, assessment tool and Newcastle-Ottawa Scale components³⁵. We used simulations with ANOVA to analyze subgroup effects in the meta-analysis. The Q_B score indicated heterogeneity in the prevalence of fatigue and fatigability in older adults across the subgroups compared. All analyses were performed with Stata 16.0 version.

Study Results

A total of 3896 studies were identified through four database searches and an additional 12 studies were identified through reference lists, resulting in the selection of 3907 articles for review. After removing 1029 duplicate studies, the title and abstract of the remaining 2828 studies were reviewed. 2,652 studies were excluded because they looked at the wrong people, results, and subjects. The 82 articles were reviews, research reports, letters or editorials. Of the remaining 144 articles that were reviewed in full, 123 studies were excluded. The reasons for exclusion were that 79 studies did not use validated fatigue assessment tools, 27 studies did not provide data on the prevalence of fatigue, 6 studies had duplicate subjects, and 11 studies were not available for full text. Therefore, 21 studies were finally included for the review of this study (Fig. 1).

Study Characteristics

This systematic review and meta-analysis of 21 studies involved a total of 17843 individuals (Table 1). According to country and regional breakdown, 11 studies were conducted in the America (11 studies were all in the United States.), 2 in Asia (China, Jordan), 4 in Europe (The United Kingdom, Spain, Norway, France), one in Turkey, which spans Eurasia, and three in America and Europe (Both in the United States and Denmark).

The average number of participants in each study was 850 (range, 29 to 2541). Thirteen studies used the Pittsburgh Fatigue Rating Scale (PFS) to assess fatigue, and three studies used the Fatigue Severity Scale (FSS). The other 5 studies used Chalder Fatigue Questionnaire (CFQ), the Turkish version of Checklist Individual Strength (CIS-T), and Functional Assessment of Chronic Illness Therapy-Fatigue Scale (FACIT), The Fatigue Symptom Inventory (FSI), Visual Analogue Scales (VAS). Eight studies addressed fatigue, 12 studies addressed physical fatigability, and 6 studies addressed mental fatigability.

Table 1. Characteristics of 21 studies included in the meta-analysis
Study	Country	Economic level	Total No.of Participants	Average of	Men，No(％)	Assessment tool	Cut-off	No.of Participants with fatigue	NOS
Study	Country	Economic level	Total No.of Participants	age, mean(SD)	Men，No(％)	Assessment tool	Cut-off	No.of Participants with fatigue	NOS
Glynn et al. 2022	USA and Denmark	developed country	2258	73.5(10.4)	1023（45.3）	PFS	PFS Physical ≥15	948	5
Alfini et al. 2020	USA	developed country	382	73.1(10.3)	179(46.9)	PFS	PFS Physical ≥15; PFS Mental ≥13	Physical, n=160; Mental, n=83	4
Simonsick et al. 2018	USA	developed country	579	73.6(NR)	271（46.8）	PFS	PFS Physical ≥15; PFS Mental ≥13	Physical, n=238; Mental, n=131	3
Cooper et al. 2019	UK	developed country	793	Range=68	337(42.3)	PFS	PFS Physical ≥15	412	5
Pérez et al. 2019	Spain	developed country	79	77.2(5.0)	19(24.1)	PFS	PFS Physical ≥15	63	3
Egerton et al. 2016	Norway	developed country	980	73.4(1.9)	509(51.9)	FSS	≥28	87	4
Tennant et al. 2012	USA	developed country	30	80.2(4.3)	7 (23.4)	FSS	≥35	14	2
Hu et al. 2021	China	developing country	457	84.8(5.8)	182(39.8)	PFS	PFS Physical ≥15	403	4
Banerjee et al. 2022	USA	developed country	48	68.1(9.4)	10(20.8)	FSI	≥ 3	27	4
Malak et al. 2021	Jordan	developing country	250	71.3(7.5)	120(48.0)	FACIT--Fatigue Scale	< 30	141	5
Blain et al. 2021	France	developed country	1471	Range≥65	485(33.0)	VAS	Female:≥5; Male ≥4	886	4
Cho et al. 2019	USA	developed country	2541	72.6(8.4)	1357(53.4)	CFQ	≥4	571	5
LaSorda et al. 2020	USA and Denmark	developed country	2355	73.7(10.5)	1066(45.3)	PFS	PFS Physical ≥15	992	5
Başkurt et al. 2012	Turkey	developing country	99	69.6(7.2)	50(50.5)	CIS-T	>76	54	2
Cohen et al. 2021	USA and Denmark	developed country	2361	73.6(10.5)	1068(45.2)	PFS	PFS Mental ≥13	585	5
Qiao et al. 2022	USA	developed country	1113	84.1(3.9)	1113(100.0)	PFS	PFS Physical ≥15; PFS Mental ≥13	Physical:597; Mental:247	5
Schnelle et al. 2012	USA	developed country	43	85.3(5.9)	NR	FSS	>4	16	3
Moored et al. 2021	USA	developed country	1672	84.2(4.0)	1672(100.0)	PFS	PFS Physical ≥15; PFS Mental ≥13	Physical:917; Mental:387	5
Graves et al. 2021	USA	developed country	181	71.3(6.7)	38(21.0)	PFS	PFS Physical ≥15	111	3
Wasson et al. 2019	USA	developed country	29	77.2(5.5)	4(13.8)	PFS	PFS Physical ≥15; PFS Mental ≥13	Physical: 19;	3
Wasson et al. 2019	USA		29	77.2(5.5)	4(13.8)	PFS	PFS Physical ≥15; PFS Mental ≥13	Mental: 19	3
Davis et al. 2021	USA	developed country	122	Range≥80	56(45.9)	PFS	PFS Physical ≥15	98	3
Abbreviations: CFQ, Chalder Fatigue Questionnaire; CIS-T, the Turkish version of Checklist Individual Strength; FACIT-Fatigue Scale, Functional Assessment of Chronic Illness Therapy-Fatigue Scale; FSI, Fatigue Symptom Inventory; FSS, Fatigue Severity Scale; PFS, Pittsburgh Fatigability Scale; VAS, visual analogue scales; NOS, Newcastle-Ottawa score; NR, not reported.

Study quality

When the Newcastle-Ottawa Quality Assessment criteria was used to score the quality of included studies (out of a total of 5 points), there were 2 studies with a score of 2, 6 studies with a score of 3, 4 studies with a score of 4, and 9 studies with a score of 5 (the scores of individual studies are shown in eTable 1 in the Supplementary Material). All included studies used validated measurement instruments with valid cutoff scores (n=21, 100.0%). On the other hand, 9 studies (42.8%) had suboptimal sample size representation. 7 studies (33.3%) had a sample size of less than 200 participants or convenience samples. In 4 studies (19.0%), the comparability between responders and non-responders was not satisfactory, or the response rate or characteristics of responders and non-responders were not described; Two studies (9.5%) did not report descriptive statistics, were incomplete or did not include appropriate dispersion measures.

Pooled and Stratified Prevalence of Fatigue in Older Adults

Based on the random effects model, the prevalence of fatigue in older adults was 42.6% (95% CI, 26.2%-59.0%). The prevalence of perceived physical fatigability was 58.2% (95% CI, 49.2%-67.2%), and the prevalence of perceived mental fatigability was 24.0% (95% CI, 21.2%-26.8%). There was significant heterogeneity among the studies. The I² of fatigue, perceived physical fatigability and mental fatigability prevalence were 99.4%, 98.8% and 81.4%, respectively (Fig. 2).

Subgroup Analysis

To further identify the source of heterogeneity, we conducted subgroup analyses according to different characteristics of the included literature (gender, regional economic level, age, sample representativeness, sample size, comparability of respondents and non-respondents, literature quality score).

Fatigue in older adults by gender

Nine studies provided prevalence estimates by gender (Table 2). The prevalence of fatigue was 39.1% in female and 40.7% in male. The perceived physical fatigability of older adults was 60.3% in female, and the perceived mental fatigability was 26.3%. 58.8% of the male perceived physical fatigability, and 22.2% of male perceived mental fatigability. Subgroup analysis showed no significant difference between genders (p=0.460; p=0.921; p=0.123).

Fatigue in older adults by regional economic level

The results of subgroup analysis showed that for countries with different levels of economic development, the prevalence of perceived physical fatigability and general fatigue among older adults was statistically significant (Table 2). The prevalence of perceived physical fatigability was 55.3% in developed countries and 88.2% in developing countries (p < .001). The prevalence of common fatigue was 38.1% in developed countries and 55.9% in developing countries (p = 0.046).

Fatigue in older adults by age

The pooled prevalence of perceived physical fatigability was significantly different between the older age group under 80 years and the older age group 80 years and above (p = 0.033) (Table 2).

Other sources of heterogeneity: study-level characteristics

Subgroup analyses indicated that the pooled prevalence of fatigue in older adults did not significantly vary according to study-level characteristics (Table 3). This included sample representativeness (Q_B=0.1, p=0.751), sample size (Q_B=0.3, p=0.579, comparability of respondents and non-respondents (Q_B=1.7, p=0.195), descriptive statistics (Q_B=0.1, p=0.696), NOS score (Q_B=1.7, p=0.195).

The prevalence of perceived physical fatigability among older adults varied significantly across strata of the components of the Newcastle-Ottawa scale (Table 4). This included representability of the sample (Q_B=25.8, p< .001), sample size (Q_B=7.1, p=0.008), comparability of respondents and non-respondents (Q_B=13.7, p< .001), and literature quality score (Q_B=11.8, p=0.001).

The prevalence of perceived mental fatigue among older adults varied significantly at the level of sample representativeness (Q_B=22.8, p< .001) and sample size (Q_B=22.8, p< .001) for the components of the Newcastle-Ottawa scale (Table 5).

In this systematic review and meta-analysis, the available evidence was summarized and meta-analysis methods were used to estimate the prevalence of fatigue in older adults. A total of 21 articles were included in this study to provide estimates of the prevalence of fatigue in a total population of 17843 older adults respondents. The overall random effect prevalence of fatigue in old age was 42.6%, indicating that approximately 2 out of every 5 older adults worldwide are affected by fatigue. However, given that self-reported fatigue has a self-paced character, we also assessed fatigability in older adults¹²; ²³. Fatigability allows us to describe an individual's susceptibility to experiencing fatigue in the context of quantifiable demands of fixed intensity and duration³⁶. Routine assessment of fatigability may help to identify older adults who are susceptible to a greater than expected decline in function¹⁸.

Table 2. Prevalence of fatigue and fatigability among older adults by country or regional level of economic development, gender, and age
Subgroups	No. of studies	Prevalence (%)	95% CI	Test for subgroup difference
Physical Fatigability
developed country	11	55.3	46.8-63.8	I² = 98.9, τ² =0.027, p < .001
developing country	1	88.2	85.2-91.1	I² = 98.9, τ² =0.027, p < .001
female	5	60.3	34.5-86.1	I² = 99.3, τ² =0.048, p =0.921
male	7	58.8	45.7-72.0	I² = 99.3, τ² =0.048, p =0.921
≥80	2	84.6	71.4-97.9	I² = 99.6 τ² =0.065 P=0.033
<80	2	47.4	26.0-78.9	I² = 99.6 τ² =0.065 P=0.033
Mental Fatigability
female	1	26.3	21.4-31.2	I² =0.02 τ² < .001 P=0.123
male	3	22.2	20.5-23.9	I² =0.02 τ² < .001 P=0.123
fatigue
developed country	6	38.1	21.3-54.8	I² =99.2 τ² =0.036 P=0.046
developing country	2	55.9	50.7-61.1	I² =99.2 τ² =0.036 P=0.046
female	3	39.1	11.0-67.2	I² =99.4 τ² =0.061 P=0.947
male	3	40.7	4.0-77.4	I² =99.4 τ² =0.061 P=0.947

Table 3. Prevalence of fatigue stratified by Newcastle-Ottawa Scale components
Newcastle-Ottawa Component	No. of studies	Prevalence (%)	95%CI (%)	Q-value	P-value	Tau²	Heterogeneity I²(%)
Sample representativeness
Less	4	40.1	16.9-63.4	1108.2	< .001	0.054	99.4
More	4	44.9	27.8-61.8	134.2	< .001	0.027	95.7
Between groups				0.10	0.751
Sample size
<200 participants	3	47.2	36.2-58.2	3.84	0.146	0.005	48.6
≥200 participants	5	40.5	19.7-61.3	1204.3	< .001	0.055	99.7
Between groups				0.31	0.579
Respondent and non-respondent comparability
Less comparable	2	52.7	44.1-61.3	0.57	0.448	< .001	< .001
More comparable	6	40.0	22.7-57.3	1206.8	< .001	0.045	99.5
Between groups				1.68	0.195
Descriptive Statistics
Less detail	1	46.7	28.8-64.5	0.15	--	< .001	--
More detail	7	42.0	26.7-57.2	1239.6	< .001	0.040	99.4
Between groups				0.15	0.696
NOS
<3	2	52.7	44.1-61.3	0.57	0.448	< .001	< .001
≥3	6	40.0	22.7-57.3	1206.8	< .001	0.045	99.5
Between groups				1.68	0.195

Fatigability has both physical and mental dimensions²⁴. The perception of physical fatigue can be described as a lack of physical energy, whereas mental fatigue can be described as a perception of mental fatigue or a lack of thinking energy³⁷. Our findings revealed that perceived mental fatigability in older adults was much lower than perceived physical fatigability (24.0% (95%CI, 21.2%–26.8%) vs 58.2% (95%CI, 49.2%–67.2%)) (Fig. 2). This may be partly because recent analyses of fatigue studies suggest that mental fatigability can be caused by physical fatigability³⁶; ³⁸. This concept is supported by earlier findings suggesting that higher mental fatigability is associated with a sharp decline in physical functioning²⁰; ³⁸. Secondly, studies in the older adults have mainly focused on physical fatigue in recent years³⁹; ⁴⁰. Therefore, there is a possibility of publication bias.

Table 4. Prevalence of perceived physical fatigability stratified by Newcastle-Ottawa Scale components
Newcastle-Ottawa Component	No. of studies	Prevalence (%)	95%CI (%)	Q-value	P-value	Tau²	Heterogeneity I²(%)
Sample representativeness
Less	5	75.9	65.7-86.1	52.6	< .001	0.011	96.9
More	7	46.9	42.2-51.6	127.0	< .001	0.004	99.6
Between groups				25.8	< .001
Sample size
<200 participants	4	72.5	62.1-82.5	17.5	0.001	0.008	67.8
≥200 participants	8	52.0	41.1-62.9	807.7	< .001	0.025	99.4
Between groups				7.08	.008
Respondent and non-respondent comparability
Less comparable	2	41.4	38.3-44.5	0.06	0.810	< .001	0.17
More comparable	10	61.7	51.4-72.0	872.5	< .001	0.026	99.0
Between groups				13.67	< .001
Descriptive Statistics
Less detail	1	41.1	37.1-45.1	< .001		< .001
More detail	11	58.3	48.7-67.8	891.2	< .001	0.027	98.9
Between groups				11.8	0.001

Fatigue is common in older adults. Fatigue is not only a symptom, but also a multifactorial condition that can significantly affect the quality of life of older adults¹¹; ⁴¹. Therefore, the role of the healthcare worker is essential to identify, assess, and manage fatigue through a multidisciplinary approach. Subgroup analyses in this review showed that the level of economic development in different countries or regions had a significant impact on the prevalence of physical fatigue and general fatigue in older adults. The possible reason for this situation is the relevant support policies for the diversification of people's quality of life in developed countries or regions, and the older adults in these regions tend to seek professional help to help them get rid of fatigue when they are tired, such as seeking multidisciplinary help from professionals interventions in health care institutions and social medical insurance ^42-44. However, the absence of a significant gender difference in fatigue was somewhat unexpected. In some cohort studies, the prevalence of fatigue in women was higher than that in men²⁰; ⁴⁵; ⁴⁶. This finding may be due to the fact that less than half of the studies (n=9) provided sex-specific prevalence estimates, limiting our ability to draw substantive conclusions. Although geographic differences in prevalence did not emerge, we were unable to estimate other important sources of variation related to geographic location. Such related differences may include differences in medical institutions, differences in access to fatigue-related management services and resources, and differences in religious culture⁴⁷; ⁴⁸. In addition, other methodological factors that we did not study may be important, such as issues related to fatigue response time.

Table 5. Prevalence of perceived mental fatigability stratified by Newcastle-Ottawa Scale components
Newcastle-Ottawa Component	No. of studies	Prevalence (%)	95%CI (%)	Q-value	P-value	Tau²	Heterogeneity I²(%)
Sample representativeness
Less	1	65.5	48.2-82.8	< .001		< .001	.
More	5	23.3	22.1-24.6	4.23	0.376	< .001	22.2
Between groups				22.8	< .001
Sample size
<200 participants	1	65.5	48.2-82.8	< .001	--	< .001	--
≥200 participants	5	23.3	22.1-24.6	4.23	0.376	< .001	22.2
Between groups				22.8	< .001
Respondent and non-respondent comparability
Less comparable	2	22.3	19.6-24.9	0.11	0.743	< .001	0.01
More comparable	4	32.4	13.8-51.0	25.6	< .001	0.034	99.5
Between groups				1.12	0.290
Descriptive Statistics
Less detail	1	22.6	19.2-26.0	< .001	--	< .001	--
More detail	5	29.8	15.7-43.9	26.54	< .001	0.024	99.2
Between groups				0.94	0.333

Overall, our findings suggest that fatigue is common among older adults, which represents a considerable public health challenge. Fatigue can serve as a physiological warning signal, and an increase in fatigue may indicate an impending health disaster. For example, after a normal amount of activity, feeling unprecedented fatigue, should be alert to whether it is caused by heart disease⁴⁹. Weakness in bilateral arm elevation is a warning symptom of stroke⁵⁰. Therefore, given the large impact of fatigue on health quality of life in the older adults, future management and mitigation are urgently needed to reduce the degree of fatigue in the older adults⁵¹. The subgroup analysis of this study highlights the need for individualized intervention strategies that take into account individual health status, lifestyle factors and specific fatigue symptoms. These strategies may include, but not limited to, nutrition adjusting, tailored according to individual ability, cognitive behavioral therapy and physical activity plan appropriate drug intervention^52-54. In addition, the subgroup analysis of this study demonstrates the importance of demographic approaches, suggesting that interventions for fatigue should sensitively consider the different needs of different age, gender, and socioeconomic groups.

Nevertheless, there are several strengths in this review. First, we conducted a systematic analysis of articles on fatigue and fatigability in older adults using a relatively comprehensive search strategy and inclusion and exclusion criteria. To our knowledge, this is the first systematic review and meta-analysis of the prevalence of fatigue in older age. Secondly, this study distinguishes between fatigue and perceived physical and mental fatigue in older adults. Thereby more accurately describing the specific types of fatigue in older adults. Timely capture of impending physical and cognitive decline and subclinical disease burden based on fatigability assessment results⁵⁵.Several potential limitations should be mentioned in this meta-analysis. First, the high heterogeneity observed throughout the study was not explained by the relevant subgroup analysis, although this is an expected feature of an epidemiological meta-analysis. However, it must be confirmed that the conclusions drawn in this review are preliminary. Future studies need to be operated at a higher consistency on fatigue, and to explore the effects of confounding variables, as much as possible to reduce the heterogeneity of research. Second, the form of fatigue assessment in the literature included in this study was self-report, and no relevant literature using performance fatigability measures was included. Although fatigue assessment by the PFS scale is self-reported after a defined performance test, it should not be ignored that fatigue as a subjective perception has the subjective characteristics of self-paced progress. Third, most of the studies included in this review used cross-sectional rather than longitudinal designs, and we only extracted cross-sectional data from longitudinal studies. Based on this, correlation analysis of the underlying mechanisms of fatigue could not be performed in this study.

In conclusion, the results of this study illustrate the prevalence of fatigue in the older adults, which provides relevant epidemiological data to support relevant studies on fatigue in the older adults. The situation of fatigue among the older adults is not optimistic. Given that fatigue can to some extent represent a physiological warning system, early and regular assessment of fatigue should be part of routine health screening programs for older adults, which has important implications for improving the quality of life of older adults and for future clinical benefits. Further cohort studies are needed in the future to identify specific effective strategies to prevent and treat negative health outcomes arising from fatigue in older adults.

Author Contribution

Ting Hu and Fen Yang conceived and designed the study, and Ting Hu, Xueyang Zhao developed the protocol for this study and screened the articles and reported the results. Qiuchen Duan, and Feiling Wang provided consultations for data analysis and check. Ting Hu drafted the manuscript, while Fen Yang and Feiling Wang critically reviewed and revised it. Fen Yang provided language help. All authors approved the final version for publication and agreed to be accountable for all aspects of the work.

Data Availability

The datasets used or analysed during the current study available from the corresponding author on reasonable request.

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No competing interests reported.

SupplementaryMaterial.pdf

Prevalence of Fatigue and Perceived Fatigability in Older Adults: A Systematic Review and Meta-analysis

Status:

Version 1

Abstract

Figures

Introduction

Methods

Results

Discussion

Conclusion

Declarations

Author Contribution

Data Availability

References

Additional Declarations

Supplementary Files

Status:

Version 1