Prevalence and severity of perceived mental fatigability in older adults: The Long Life Family Study

The Influence of Mental Fatigue on Physical Performance and Its Relationship with Rating Perceived Effort and Enjoyment in Older Adults

The study investigated the influence of mental fatigue on older people's enjoyment during a series of physical exercises. Using a randomized cross-over design, participants (n = 35) completed a 6-minute walking test - 6MWT, a Timed Up and Go-TUG test and three sets of knee extension exercise (first set: KE1, second set: KE2, third set: KE3) under two experimental conditions (control or mental fatigue). The Nonparametric Analysis of Longitudinal Data in Factorial Experiments was used to compare the number of repetitions performed during three sets of resistance exercise between conditions. The same analysis method was applied to compare the perception of effort and enjoyment across five moments (Post-6MWT, Post-TUG, Post-KE1, Post-KE2, Post-KE3) and two conditions and the Visual Analogue Scales (VAS) across four moments (baseline, Pre-6MWT, Pre-TUG, Pre-KE) and two conditions. Mental fatigue did not affect the physical function, perception of effort and enjoyment of exercise in older people. Participants, however, reported higher enjoyment for walking and dynamic balance compared to strength exercise. Mental fatigue had no effect on the physical function, perception of effort and enjoyment of exercise of older people. Participants presented a higher enjoyment for walking and dynamic balance compared to strength exercise. Given the importance of resistance exercises for health, clinicians should prioritize resources to education programs emphasizing the benefits of resistance exercise in both short- and long-term health. Including social interaction opportunities in physical exercise programs and prescribing activities appropriate to participants' ability levels could enhance engagement and adherence.

Perceived physical and mental fatigability in older adults with and without multiple sclerosis

BACKGROUND

Fatigue stands out as a prevalent and debilitating symptom in both Multiple Sclerosis (MS) and the aging population. Traditional methods for measuring perceived fatigue may not adequately account for individual activity differences, leading to varied prevalence rates. Perceived fatigability anchors fatigue to specific activities with predetermined intensity and duration, thereby mitigating self-pacing bias. Despite its potential, perceived fatigability is poorly understood in older adults, particularly those with neurological conditions, including MS. This study thus aimed to (1) investigate whether, among older adults, MS was associated with worse perceived physical and mental fatigability; (2) evaluate whether, among older adults with MS (OAMS), greater patient-reported disease-related disability was associated with worse perceived physical and mental fatigability.

METHODS

Participants were 96 older adults with a physician-confirmed diagnosis of MS (mean age: 64.6 ± 4.2) and 110 healthy controls (mean age: 68.2 ± 7.2), all confirmed to be dementia-free through established case conference procedures. Physical and mental fatigability were measured using the Pittsburgh Fatigability Scale, a 10-item questionnaire (score range: 0 to 50) designed to assess fatigue levels that individuals expect to feel after engaging in a range of typical activities for older adults. MS disease-related disability was assessed with the Patient Determined Disease Steps scale, which ranges from 0 (normal) to 8 (bedridden), with scores ≥ 2 indicating worse MS-related disability after a median split. Separate linear regression models were performed to investigate associations between group status (MS vs. Control) as the predictor and perceived physical and mental fatigability scores as the outcome variables. Within the MS group, additional linear regression models were performed to explore the relationship between disease-related disability and fatigability levels. All models adjusted for age, sex, race, education, global health, general cognitive function, and depressive symptoms levels.

RESULTS

The fully adjusted models yielded the following key findings: OAMS reported significantly higher levels of perceived physical fatigability (M = 25.11 ± 9.67) compared to controls (M = 17.95 ± 8.35) (p = 0.003). Similarly, the perceived mental fatigability in OAMS (M = 16.82 ± 11.79) was significantly greater than that in controls (M = 9.15 ± 7.12) (p = 0.003). Within the MS group, individuals with greater disease-related disability reported significantly greater levels of both physical (M = 30.13 ± 7.71 vs. 18.67 ± 8.00, p < 0.001) and mental fatigability (M = 20.31 ± 12.18 vs. 12.33 ± 9.69, p = 0.009) compared to those with lower MS-related disability. Of note, the significance of these findings persisted in models that adjusted for depressive symptoms.

CONCLUSION

Our study provides compelling evidence that OAMS exhibit significantly higher perceived physical and mental fatigability compared to healthy controls. Additionally, worse MS-related disability correlates with worse physical and mental fatigability. These results persist after adjusting for confounders including depressive symptoms. Our findings underscore the necessity of holistic management strategies that cater to both physical and psychological aspects of MS, laying a foundation for future studies to uncover the pathophysiological mechanisms of fatigability in older adults with and without MS.

Associations of depression and perceived physical fatigability with white matter integrity in older adults

BACKGROUNDS

Fatigability is prevalent in older adults. However, it is often associated with depressed mood. We aim to investigate these two psychobehavioral constructs by examining their underpinning of white matter structures in the brain and their associations with different medical conditions.

METHODS

Twenty-seven older adults with late-life depression (LLD) and 34 cognitively normal controls (CN) underwent multi-shell diffusion MRI. Fatigability was measured with the Pittsburgh Fatigability Scale. We examined white matter integrity by measuring the quantitative anisotropy (QA), a fiber tracking parameter with better accuracy than the traditional imaging technique.

RESULTS

We found those with LLD had lower QA in the 2nd branch of the left superior longitudinal fasciculus (SLF-II), and those with more physical fatigability had lower QA in more widespread brain regions. In tracts associated with more physical fatigability, the lower QA in left acoustic radiation and left superior thalamic radiation correlated with higher blood glucose (r = - 0.46 and - 0.49). In tracts associated with depression, lower QA in left SLF-II correlated with higher bilirubin level (r = - 0.58).

DISCUSSION

Depression and fatigability were associated with various white matter integrity changes, which correlated with biochemistry biomarkers all related to inflammation.

Unsupervised robot-assisted rehabilitation after stroke: feasibility, effect on therapy dose, and user experience

BACKGROUND

Unsupervised robot-assisted rehabilitation is a promising approach to increase the dose of therapy after stroke, which may help promote sensorimotor recovery without requiring significant additional resources and manpower. However, the unsupervised use of robotic technologies is not yet a standard, as rehabilitation robots often show low usability or are considered unsafe to be used by patients independently. In this paper we explore the feasibility of unsupervised therapy with an upper limb rehabilitation robot in a clinical setting, evaluate the effect on the overall therapy dose, and assess user experience during unsupervised use of the robot and its usability.

METHODS

Subacute stroke patients underwent a four-week protocol composed of daily 45 min-sessions of robot-assisted therapy. The first week consisted of supervised therapy, where a therapist explained how to interact with the device. The second week was minimally supervised, i.e., the therapist was present but intervened only if needed. After this phase, if participants learnt how to use the device, they proceeded to two weeks of fully unsupervised training. Feasibility, dose of robot-assisted therapy achieved during unsupervised use, user experience, and usability of the device were evaluated. Questionnaires to evaluate usability and user experience were performed after the minimally supervised week and at the end of the study, to evaluate the impact of therapists' absence.

RESULTS

Unsupervised robot-assisted therapy was found to be feasible, as 12 out of the 13 recruited participants could progress to unsupervised training. During the two weeks of unsupervised therapy participants on average performed an additional 360 min of robot-assisted rehabilitation. Participants were satisfied with the device usability (mean System Usability Scale scores > 79), and no adverse events or device deficiencies occurred.

CONCLUSIONS

We demonstrated that unsupervised robot-assisted therapy in a clinical setting with an actuated device for the upper limb was feasible and can lead to a meaningful increase in therapy dose. These results support the application of unsupervised robot-assisted therapy as a complement to usual care in clinical settings and pave the way to its application in home settings.

TRIAL REGISTRATION

Registered on 13.05.2020 on clinicaltrials.gov (NCT04388891).

Lower Physical Activity Modifies the Association between Perceived Fatigability and Executive Function but not Memory: The Study of Muscle, Mobility and Aging (SOMMA)

OBJECTIVE

Emerging evidence shows that perceived fatigability-the quantification of vulnerability to fatigue in relation to specific intensity and duration of activities-may be associated with cognitive function. We sought to quantify associations with multiple domains of cognitive function and the role of physical activity (PA).

METHODS

SOMMA participants completed the Pittsburgh Fatigability Scale (PFS) Physical and Mental subscales (each range 0-50; higher scores=greater fatigability) and three cognitive function assessments [Digit Symbol Substitution Test (DSST), executive function; Montreal Cognitive Assessment (MoCA), general function; and California Verbal Learning Test (CVLT), memory]. Linear regression quantified associations cross-sectionally between each PFS subscale and cognitive assessment scores adjusting for covariates. Effect modification by volume and intensity of accelerometer-measured PA was assessed.

RESULTS

In 873 participants (59.2% women; age 76.3±5.0; 85% White), mean PFS Physical, Mental, and DSST scores were 15.8±8.7, 7.7±7.8, and 55.4±13.7. After adjustments, for each 4-point higher PFS Physical and 3-point higher PFS Mental, participants had nearly one fewer correct DSST items [β coefficient and 95% confidence interval for PFS Physical: -0.69 (-1.09, - 0.29); PFS Mental: -0.64 (-0.97, -0.30)]. Volume and intensity of PA modified the association of PFS Mental and DSST ( P interactions <0.01). All associations were strongest in those with the lowest volume and intensity of PA. PFS was not associated with MoCA or CVLT.

DISCUSSION

Greater perceived fatigability may be associated with poorer executive function, but not memory. Individuals with greater perceived fatigability, particularly those less active, might benefit from interventions that reduce fatigability and may beneficially influence cognitive function.

Measuring and Understanding the Health Impact of Greater Fatigability in Older Adults: A Call to Action and Opportunities

Different from fatigue, an instantaneous state of tiredness, weakness and lack of energy, fatigability is a trait that contextualizes whole-body fatigue to the level of activity (i.e., intensity and duration) with which the fatigue is associated. Fatigability can be perceived or performance-related. Measuring fatigability improves upon traditional fatigue measures by accounting for self-pacing as older adults likely slow down or limit their daily activity to maintain fatigue in a tolerable range. Anchoring fatigue to activities/tasks improves sensitivity and allows for meaningful comparisons across individuals/between studies, as well as evaluating change over time and treatment effects. Two well-validated approaches are utilized to measure perceived fatigability: 1) a 5-minute slow-paced (1.5 mph/0.67 m/s, 0% grade) treadmill walk immediately followed by Borg rating of perceived exertion; and 2) a self-administered 10-item questionnaire, Pittsburgh Fatigability Scale, with both physical and mental subscales. Many walking-based performance fatigability measures are based on certain lap time or distance, while the Pittsburgh Performance Fatigability Index uses raw accelerometry data to quantify percent of cadence decline over the entire long distance walking tasks. Perceived fatigability prevalence ranges from 20-90% in older adults varying by assessment tool, and is higher with advancing age and in women compared to men. Fatigability is associated with physical and cognitive function, fall risk, mobility decline, and mortality. Unfortunately, the available research lacks representativeness in terms of racial and ethnic diversity. The time is now to incorporate our established sensitive and validated fatigability measures into global research and clinical practice to better understand mechanistic underpinnings and reveal intervention effects to reduce the burden and lessen the consequences of greater fatigability worldwide.

Role of Perceived Physical and Mental Fatigability Severity on Prospective, Recurrent, and Injurious Fall Risk in Older Men

BACKGROUND

Falls occur annually in 25% of adults aged ≥65 years. Fall-related injuries are increasing, highlighting the need to identify modifiable risk factors.

METHODS

Role of fatigability on prospective, recurrent, and injurious fall risk was examined in 1 740 men aged 77-101 years in the Osteoporotic Fractures in Men Study. The 10-item Pittsburgh Fatigability Scale measured perceived physical and mental fatigability (0-50/subscale) at Year 14 (2014-16); established cut-points identified men with more severe perceived physical (≥15, 55.7%), more severe mental (≥13, 23.7%) fatigability, or having both (22.8%). Prospective, recurrent (≥2), and injurious falls were captured by triannual questionnaires ≥1 year after fatigability assessment; risk of any fall was estimated with Poisson generalized estimating equations, and likelihood of recurrent/injurious falls with logistic regression. Models adjusted for age, health conditions, and other confounders.

RESULTS

Men with more severe physical fatigability had a 20% (p = .03) increased fall risk compared with men with less physical fatigability, with increased odds of recurrent and injurious falls, 37% (p = .04) and 35% (p = .035), respectively. Men with both more severe physical and mental fatigability had a 24% increased risk of a prospective fall (p = .026), and 44% (p = .045) increased odds of recurrent falling compared with men with less severe physical and mental fatigability. Mental fatigability alone was not associated with fall risk. Additional adjustment for previous fall history attenuated associations.

CONCLUSIONS

More severe fatigability may be an early indicator to identify men at high risk for falls. Our findings warrant replication in women, as they have higher rates of fatigability and prospective falls.

Dual Roles of Cardiorespiratory Fitness and Fatigability in the Life-Space Mobility of Older Adults: The Study of Muscle, Mobility and Aging (SOMMA)

BACKGROUND

Cardiorespiratory fitness and perceived fatigability are interrelated components of physical capacity that may jointly influence movement within one's living environment (life-space mobility). We examined whether fitness and fatigability were associated with life-space mobility in community-dwelling older adults, and whether the association of fitness with life-space varied by the level of perceived fatigability.

METHODS

Participants were from the Study of Muscle, Mobility and Aging (SOMMA) baseline cohort (N = 775, mean age 76.1 years). Life Space Assessment scores incorporated level, frequency, and assistance used (personal, devices) for life-space mobility. Fitness was measured as VO2peak from symptom-limited treadmill testing. Fatigability cut-points included: (i) Borg Rating of Perceived Exertion (RPE) ≥ 10 after a fixed-speed (1.5 mph) treadmill test, (ii) the Pittsburgh Fatigability Scale (PFS) Physical ≥ 15, and (iii) PFS Mental ≥ 13. The total count of cut-points was used as a composite fatigability measure (range: 0-3). Linear regressions were adjusted for demographic, lifestyle, and health confounders.

RESULTS

Better fitness was associated with greater life-space, but the association plateaued at higher fitness levels (VO2peak > 18). Life-space was significantly lower for individuals meeting ≥2 fatigability criteria (vs none), attributable mainly to more severe physical, but not mental, fatigability. In moderation analyses, the fitness-life-space association was significant only for those with RPE ≥ 10 but did not differ by PFS.

CONCLUSION

Fitness below a critically low threshold was associated with limited life-space mobility, suggesting that certain older individuals may need to operate close to their maximum aerobic capacity to traverse daily environments; these associations were driven by those with more severe physical fatigability.

Mental Fatigue Is Associated with Subjective Cognitive Decline among Older Adults

Both Subjective Cognitive Decline (SCD) and mental fatigue are becoming increasingly prevalent as global demographics shifts indicate our aging populations. SCD is a reversible precursor for Alzheimer's disease, and early identification is important for effective intervention strategies. We aim to investigate the association between mental fatigue-as well as other factors-and SCD. A total of 707 old adults (aged from 60 to 99) from Shanghai, China, participated in this study and completed self-reported instruments covering their cognitive and mental status as well as demographic information. Mental fatigue status was assessed by using four items derived from the functional impairment syndrome of the Old Adult Self Report (OASR). SCD was assessed by using the Memory/Cognition syndrome of OASR. A total of 681 old adults were included in the current study. The means of SCD significantly differed between each group of factors (age, gender, and mental fatigue). The general linear regression models showed that SCD increased with age, females scored higher than males, and SCD was positively associated with mental fatigue factors including difficulty getting things done, poor task performance, sleeping more, and a lack of energy among old adults. The study also found that SCD is negatively associated with the high-income group among young-old (aged from 60 to 75) males and associated with good marital/living status with the companion of spouses/partners among young-old females. These results suggest that gender, income level, marital/living status, and mental fatigue are crucial factors in preventing SCD among old adults and are pivotal in developing early intervention strategies to preserve the mental health of an increasingly aging population.

[Asthenia, mental fatigue and cognitive dysfunction]

Conditions associated with asthenia are usually characterized by increased fatigue, impaired activities of daily living and decreased productivity. In clinical practice it is important to distinguish between idiopathic chronic fatigue (primary or functional asthenia) and chronic fatigue syndrome (CFS). Fatigue can also be classified by neuromuscular and/or cognitive and mental fatigue. The article discusses the neuroanatomical basis and focuses on the neurocognitive theory of pathological fatigue. In addition the relationship between mental stress, fatigue and cognitive impairments such as subjective cognitive impairment (SCI) and mild cognitive impairment (MCI) are also discussed. We discuss the rationale that for treatment of asthenic conditions accompanied by cognitive dysfunction it is justified to use combination therapy - fonturacetam and a preparation containing nicotinoyl-GABA and Ginkgo Biloba.

Changes in Objectively Measured Physical Activity Are Associated With Perceived Physical and Mental Fatigability in Older Men

BACKGROUND

Lower physical activity (PA) is associated with greater perceived fatigability, a person-centered outcome. The association between change in PA and fatigability with advanced age has yet to be established.

METHODS

Community-dwelling older men (N = 1 113, age = 84.1 ± 3.9 years at Year 14) had free-living PA assessed using SenseWear Armband prospectively at Year 7 (2007-2009) and Year 14 (2014-2016) of Osteoporotic Fractures in Men Study, a longitudinal cohort established in 2000 (baseline). We categorized percent changes in PA into groups (large decline → large increase) for 4 metrics: step count, light intensity PA (LIPA, metabolic equivalents [METs] >1.5 to <3.0), moderate-to-vigorous PA (MVPA, METs ≥ 3.0), and sedentary behavior (SB, METs ≤ 1.5, excluding sleep). Perceived physical and mental fatigability were measured (Year 14) with the Pittsburgh Fatigability Scale (PFS, higher score = greater fatigability; range = 0-50). Associations between each metric of percent changes in PA and fatigability were examined using linear regression, adjusted for demographics, change in health conditions, and Year 7 step count or total PA (METs > 1.5).

RESULTS

Men declined 2 336 ± 2 546 (34%) steps/d, 24 ± 31 (25%) LIPA min/d, 33 ± 58 (19%) MVPA min/d, and increased 40 ± 107 (6%) SB min/d over 7.2 ± 0.7 years. Compared to large decline (% change less than -50%), those that maintained or increased step count had 3-8 points lower PFS Physical scores; those who maintained or increased LIPA and MVPA had 2-3 and 2-4 points lower PFS Physical scores, respectively (all p ≤ .01). Associations were similar, but smaller, for PFS Mental scores.

CONCLUSION

Older men who maintained or increased PA had lower fatigability, independent of initial PA. Our findings inform the types and doses of PA that should be targeted to reduce fatigability in older adults.

Prospective Associations Between Physical Activity and Perceived Fatigability in Older Men: Differences by Activity Type and Baseline Marital Status

BACKGROUND

Lower physical activity has been cross-sectionally associated with greater perceived fatigability, defined as self-reported fatigue anchored to activity intensity and duration. The temporality of this relationship, and whether it differs by activity type or marital status, remains unclear.

METHODS

In the Osteoporotic Fractures in Men Study (N = 1 759), self-reported total, exercise, and household activity were assessed using the Physical Activity Scale for the Elderly across 7 visits (2000-2016). The Pittsburgh Fatigability Scale (range: 0-50; higher scores = greater fatigability) measured physical (mean = 16.6 ± 9.7) and mental (mean = 7.8 ± 8.3) fatigability at Year 14. Least absolute deviation and linear regression were used to examine associations between baseline and change in activity over 14 years with subsequent fatigability. Models were adjusted for demographic, health, and lifestyle factors.

RESULTS

After adjustment, lower baseline (β= -0.08, 95% confidence interval [CI]: -0.12, -0.04) and greater annual declines in total activity (β = -0.09, 95% CI: -0.14, -0.05) were prospectively associated with higher Pittsburgh Fatigability Scale (PFS) Physical scores. Associations were similar for mental fatigability (both p < .05). Lower baseline leisure exercise, but not baseline household activity, predicted higher PFS Physical scores (β = -0.10 vs -0.001). In contrast, greater declines in household activity, but not declines in exercise, were associated with higher PFS Physical scores (β = -0.09 vs -0.03). Lower baseline household activity predicted higher PFS Mental scores only for unmarried men (β = -0.15, 95% CI: -0.29, -0.01, interaction p = .019).

CONCLUSIONS

Baseline total activity and leisure exercise, and declines in total and household activity, were associated with higher subsequent perceived fatigability in older men. Marital status may mitigate the contribution of household activity to subsequent fatigability.

Life-space Mobility in Older Men: The Role of Perceived Physical and Mental Fatigability

BACKGROUND

Physical performance and fatigue can limit mobility within the larger environment (life-space mobility). It is unknown whether perceived fatigability, self-reported fatigue anchored to activity intensity and duration, is independently associated with life-space.

METHODS

We assessed this cross-sectionally in Visit 4 (2014-2016) of the Osteoporotic Fractures in Men Study (MrOS; N = 1 672, Age: Mean = 84.2 ± 4.0 years). The Pittsburgh Fatigability Scale (PFS, range: 0-50; higher = greater fatigability) measured physical (Mean = 16.1 ± 9.4) and mental fatigability (Mean = 7.5 ± 7.9). Life Space Assessment scores incorporated level, frequency, and assistance used for life-space mobility (range: 0-120, higher = greater life-space mobility; life-space constriction: inability to leave neighborhood without assistance). Separate multiple linear and logistic regressions for physical and mental fatigability were sequentially adjusted for demographic, health/lifestyle, and performance measures.

RESULTS

The mean life-space mobility score was 84.6 ± 21.8, and 18% (n = 296) of men had life-space constriction. Higher physical and mental fatigability were both associated with lower life-space mobility in models adjusted for health and lifestyle factors (Physical PFS: B = -2.37, 95% confidence interval [CI]: [-3.39, -1.35]; Mental PFS: B = -1.79, 95% CI: [-2.73, -0.84]). Men with higher fatigability also had increased risk of life-space constriction (Physical PFS: OR = 1.59, 95% CI: [1.32, 1.92]; Mental PFS: OR = 1.25, 95% CI: [1.08, 1.46]). Associations were larger in magnitude for physical versus mental fatigability. Adjusting for physical performance measures more strongly attenuated associations for physical compared to mental fatigability.

CONCLUSIONS

Fatigability is linked with real-world mobility in older men, independent of their physical health. This association may be driven by separate physical and cognitive mechanisms worth examining further in longitudinal studies.

Relationship Between Personality Measures and Perceived Mental Fatigability

OBJECTIVE

Examine the association between personality measures and perceived mental fatigability.

METHODS

We performed a cross-sectional analysis in N=1670 men, age 84.3±4.1 years. Multivariable linear regression models were used to examine the covariate adjusted association between personality measures (conscientiousness, optimism, goal reengagement, and goal disengagement) and perceived mental fatigability (measured with the validated 10-item Pittsburgh Fatigability Scale, PFS).

RESULTS

One standard deviation lower conscientiousness (β=-0.91, p<.0001) and optimism (β=-0.63, p<.0001), and higher goal reengagement (β=0.51, p=.01) scores were independently associated with higher PFS Mental scores adjusted for age, cognitive function, self-reported health status, depressive symptoms, sleep disturbance, physical activity, and goal disengagement.

DISCUSSION

Lower conscientiousness, optimism, and higher goal reengagement were linked with more severe perceived mental fatigability in older men. Personality traits may potentially contribute to early risk assessment for fatigability in later life. Future work should be longitudinal in nature and include personality assessments to confirm the temporality of the relationships observed.

Association of fatigue, inflammation, and physical activity on gait speed: the Long Life Family Study

BACKGROUND

Fatigue, inflammation, and physical activity (PA) are all independently associated with gait speed, but their directionality is not fully elucidated.

AIMS

Evaluate the bidirectional associations amongst fatigue, inflammation, and PA on gait speed.

METHODS

This cross sectional study included probands (n = 1280, aged 49-105) and offspring (n = 2772, aged 24-88) in the Long Life Family Study. We assessed gait speed, fatigue with the question "I could not get going", inflammation using fasting interleukin-6 (IL-6) and high sensitivity C-reactive protein (CRP), and self-reported PA as walking frequency in the past two weeks. The two generations were examined separately using linear mixed modeling.

RESULTS

Lower fatigue, lower IL-6, and greater PA were all associated with faster gait speed in both generations (all p < 0.05); lower CRP was only associated with faster gait speed in the offspring. PA explained the association of fatigue and gait speed via a 16.1% (95% CI 9.7%, 26.7%) attenuation of the direct associations for the probands and 9.9% (95% CI 6.3%, 18.8%) in the offspring. In addition, IL-6 explained more of the association of fatigue and gait speed than the association between PA and gait speed, via a 14.9% (95% CI 9.2%, 23.4%) attenuation of the direct association in the offspring only.

DISCUSSION

Results revealed a potential directionality from fatigue to IL-6 to PA that may lead to faster gait speed. Future work should examine these relationships longitudinally to establish temporality and causality.

CONCLUSIONS

Our findings support a signal that lowering fatigue and inflammation and increasing physical activity may delay functional decline.

Psychometric properties of the Korean version of the Pittsburgh Fatigability Scale in breast cancer survivors

BACKGROUND

Fatigability has recently emerged in oncology as a concept that anchors patients' perceptions of fatigue to defined activities of specified duration and intensity. This study aimed to examine the psychometric properties of the Korean version of the Pittsburgh Fatigability Scale (K-PFS) for women with breast cancer.

METHODS

This cross-sectional study involved 196 women with breast cancer recruited from a tertiary hospital in Seoul, Korea. Reliability was evaluated using Cronbach's alpha, and confirmatory factor analysis was conducted to examine the factor structure of the K-PFS. Four goodness-of-fit values were evaluated: (1) the comparative fit index (CFI), (2) the Tucker-Lewis index (TLI), (3) the root mean square error of approximation (RMSEA), and (4) the standardized root mean square residual (SRMR).

RESULTS

Of the 196 survivors, 71.1% had greater physical fatigability (K-PFS Physical score ≥ 15) and 52.6% had greater mental fatigability (K-PFS Mental score ≥ 13). The Cronbach's alpha coefficient for the total K-PFS scale was 0.926, and the coefficients for the physical and mental fatigability domains were 0.870 and 0.864, respectively. In the confirmatory factor analysis for physical fatigability, the SRMR value (0.076) supported goodness of fit, but other model fit statistics did not (CFI = 0.888, TLI = 0.826, and RMSEA = 0.224). For mental fatigability, although three goodness-of-fit values were acceptable (CFI = 0.948, TLI = 0.919, and SRMR = 0.057), the RMSEA value (0.149) did not indicate good model fit. However, each item coefficient was statistically significant (> 0.5), and the K-PFS was therefore found to be valid from a theoretical perspective.

CONCLUSION

This study provides meaningful information on the reliability and validity of the K-PFS instrument, which was developed to meet an important need in the context of breast cancer survivors. Additional research should examine its test-retest reliability and construct validity with performance measures.