The Impact of Motor and Cognitive Fatigue on Quality of Life in Patients with MS

A decrease in physical and mental quality of life (QoL) as a result of increased motor and cognitive fatigue in patients with multiple sclerosis (MS), emphasizes the importance of effective treatment for these symptoms, according to study results published in the Multiple Sclerosis Journal. 

The varying degrees of MS disability encouraged study researchers to determine whether motor or cognitive fatigue would impact the QoL of patients independently from their physical disability. A total of 79 patients from Aalborg University Hospital in Denmark were included in this observational, cross-sectional study between the dates of November 2017 to May 2018. Only patients of at least 18 years of age, with a diagnosis of MS according to McDonald criteria 2010, and able to communicate in Danish were selected.

Study researchers instructed patients to complete the Fatigue Scale for Motor and Cognitive Functions (FSMC), Modified Fatigue Impact Scale (MFIS), and Short Form 36 (SF-36) questionnaires to assess fatigue in relation to cognitive, motor, psychosocial, and health status (physical function, pain, role limitations, vitality etc). They obtained data on disease duration and course as well as EDSS (Expanded Disability Status Scale) scores taken within 6 months from patient records.

Among the 79 patients, a majority (90%) had a diagnosis of relapsing-remitting MS (RRMS) with a median age of 44 years, a median disease duration of 9 years, and a median EDSS score of 2.5. Data from the FSMC questionnaire indicated that most patients (84%) were reportedly fatigued, with a majority (63%) reporting fatigue from MFIS data.

When assessing the relationship between fatigue and QoL, all fatigue scores indicated a significant correlation to all QoL scores (P <0.05). This remained significant after adjustment for age, disease duration, and EDSS score. The most prominent correlations were those regarding patient vitality (r=-0.80, FSMCmot), social functioning (r=-0.73, MFISps) and role limitations caused by physical problems (r=-0.70, MFIStot).

Findings indicated that patients’ motor fatigue was most closely related to QoL dimensions compared with cognitive fatigue scores. Additionally, disability status (EDSS score) was significant to all aspects of QoL except limitations due to emotional problems and mental health, with the strongest correlation to physical functioning.

Limitations to the study include its cross-sectional design and misclassification due to interobserver variation in EDSS scoring, as well as variance in the interval between EDSS and fatigue/QoL scoring. Additionally, study researchers did not further examine the role of depression in patients with MS, as fatigue may be a result of depression rather than of MS. They did not evaluate the concomitant disease and medications that may alter fatigue and sleep quality.

The study researchers concluded that the significant and differential correlation between motor and cognitive fatigue and reduced QoL indicated a need for proper assessment of fatigue in patients with MS. They added that the use of patient reported measures are necessary “to get a holistic view of the disease impact, which builds the foundation for development of appropriate and specific treatment interventions.”

Reference

Ruben SD, Hilt CC, Petersen T. Quality of life in multiple sclerosis: The differential impact of motor and cognitive fatigue. Multiple Sclerosis Journal ETC. Published online February 24 2021. doi:10.1177/2055217321996040