Highlights
- •Discrimination between fatigue as subjective sensation and fatigability as change of performance is crucial.
- •Fatigue is determined by questionnaires; while cognitive fatigability can be measured by tonic alertness.
- •15 of 17 patients working fulltime had severe fatigue according to the Fatigue Scale for Motor and Cognition (FSMC).
- •Cognitive fatigability (tonic alertness) is a better predictor of employment status three months later.
- •Alertness1 in the morning was the strongest predictor.
Abstract
Background
: Fatigue is potentially the most important factor causing unemployment in people
with Multiple Sclerosis (PwMS). Widely accepted is a discrimination between fatigue
as subjective sensation and fatigability as objective measure of change in performance.
The aim of this study was to identify, whether cognitive fatigue or cognitive fatigability
is a better predictor for employment status three months after discharge from a neurological
rehabilitation center.
Methods
: 64 PwMS (mean age 48.9, 43 females, mean time since diagnosis 14.7 years, median
Expanded Disability Status Scale (EDSS) 3.8), complaining of fatigue and reporting
difficulties with their working capacity, participated in a cognitive loading task
during inpatient rehabilitation. Reaction time performance was measured using a standardized
alertness test (TAP-M). Tonic alertness was measured at 8 a.m., 11 a.m. and 2 p.m.
Patients worked on a standardized test battery during the morning and after lunch
to induce fatigability. All of them completed the Fatigue Scale for Motor and Cognition
(FSMC), a standardized questionnaire to rate the trait component of cognitive and
motor fatigue. Their employment status was rated within a standardized interview by
phone three months after discharge from the clinic.
Results
: Mean cognitive fatigue according to the FSMC was 38.9 ± 7.4 and mean motor fatigue
41.0 ± 5.6, indicating severe cognitive and motor fatigue. 15 (88%) of 17 patients
working fulltime had severe fatigue according to the FSMC. The cognitive subscale
of the FSMC (“FSMC cognition”) did not correlate (rs = -.084, p = .512) and the motor subscale of the FSMC (“FSMC motor”) correlated rather weakly
but not significantly (rs= -.220, p = .080) with the employment status. In contrast, there was a significant and medium
correlation between alertness at 8 a.m. (alertness1) and employment status (rs = -.304, p = .014). Ordered logistic regression revealed that only alertness1 and the alertness difference between afternoon and noon (alertness difference32) predicted significantly the employment status. The FSMC motor and cognition subscales
had no predictive value for employment.
Conclusion
: Cognitive fatigability (tonic alertness at 8 a.m. or increase of reaction time during
the afternoon) is more adequate to predict employment status in PwMS three months
after discharge from the clinic than the subjective sensation of fatigue as determined
by the FSMC.
Key words
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Article info
Publication history
Published online: August 19, 2021
Accepted:
August 13,
2021
Received in revised form:
August 1,
2021
Received:
June 28,
2021
Identification
Copyright
© 2021 Published by Elsevier B.V.
