Utilizing Perceived Fatigability to Identify Cognitive and Mobility Impairments in Aging and Multiple Sclerosis

Area of Science:

• Gerontology
• Neurology
• Rehabilitation Medicine

Background:

• Perceived fatigability is common in aging and neurological conditions.
• The Pittsburgh Fatigability Scale (PFS) is validated for older adults and those with multiple sclerosis (OAMS).
• Clinical relevance of PFS subscale cut-offs for cognitive and mobility outcomes in neurologically affected aging populations requires examination.

Purpose of the Study:

• To examine the clinical relevance and subscale cut-offs of the PFS in neurologically affected aging populations.
• To assess the accuracy of PFS subscales in discriminating between multiple sclerosis (MS), mild cognitive impairment (MCI), mobility impairment, and MS-related disability.
• To determine population- and outcome-specific cut-offs for PFS subscales.

Main Methods:

• A study involving 224 older adults (109 OAMS, 115 controls) who completed the PFS, neuropsychological tests, and Short Physical Performance Battery (SPPB).
• Receiver operating characteristic (ROC) analyses were used to assess PFS subscale accuracy.
• Logistic regression adjusting for covariates refined ROC curves and cut-offs.

Main Results:

• Unadjusted PFS subscales showed moderate accuracy (AUC 0.59-0.75) for discriminating MS, MCI, and mobility impairment.
• Covariate adjustment improved accuracy, often exceeding 0.80.
• Mental fatigability better identified MCI in OAMS, while physical fatigability detected worse MS-related disability. Cut-offs were higher in OAMS than controls and varied by outcome.

Conclusions:

• PFS subscales can identify MS, cognitive impairment, and mobility impairment in older adults.
• Population- and outcome-specific cut-offs are necessary; thresholds from healthy cohorts may not apply to neurological populations.
• Covariate adjustment refines discriminative accuracy, aiding in functional monitoring needs.