Fatigue in multiple sclerosis

Abstract

Fatigue is a nonspecific but common symptom in multiple sclerosis (MS). It represents a major cause of disability, affecting the quality of life of MS patients. Most studies on MS fatigue have tried to establish its relationship with disease progression but the results have been contradictory. In view of these previous findings, we conducted a study in order to obtain additional data about fatigue in MS and its clinical correlations. Objective: To evaluate fatigue in MS patients using a specific validated scale and to appreciate its role in the disease's clinical aspects and course, highlighting some specific clinical features in these patients. Material and method: We included in this study 101 patients with MS diagnosis, regardless of disease forms, having the mean age at inclusion of 41.75 years and the female to male ratio of 8.18:1, identified within the records of the Neurology I department of the Emergency County Hospital of Cluj-Napoca. The patients had at least one neurological assessment over the past two years prior to study inclusion (June 2014 - June 2016). "Modified Fatigue Impact Scale" - MFIS was used for fatigue assessment, with a total score of 0 to 84, a higher score indicating greater fatigue. A cut-off score of 38 was chosen to distinguish patients with fatigue from those without fatigue. According to the presence of fatigue (MFIS score ≥ 38), the patients were divided into two groups: the 43 patients with fatigue were included in group A while the 58 patients without fatigue were included in group B. Data related to clinical and imaging features and to disease course were evaluated and compared between the two groups. Results: Fatigue was reported by 43.57% of patients, with a mean MFIS score of 60.97 (standard deviation (SD) 11.81). In group A, MFIS average score was 51.70 (SD 13.57) compared to 18.55 (SD 10.06) in group B. We haven't noticed a difference between the two groups in terms of age at MS onset (29.35 years (SD 9.24) in group A vs 29.9 years (SD 9.87) in group B, p=0.778). Instead, the age at study inclusion was higher in patients with fatigue (45.79 years (SD 11.52) in group A vs 37.71 years (SD 12.97) in group B, p=0.002). As age was higher, the severity of fatigue, as expressed by MFIS score, was greater. The disease duration in group A had the median of 13.17 years (interquartile range (IQR) 9.58 - 19.25), significantly higher than that observed in group B (the median of 6.21 years (IQR 2.67 - 13.83), p < 0.001). The progression to a secondary-progressive (SPMS) form was not different between the group A and B (158.8 vs 141.4 months, p = 0.709) but the SP form was more frequent in patients with fatigue (46.51% vs 8.62%, p < 0.001). An important finding of the study was the association between fatigue and disease severity. The patients in group A had a median EDSS score of 4.00 (IQR 3.0 - 6.0), significantly higher than the median EDSS score of 2.0 (IQR 1.5 - 2.5) observed in group B, p < 0.001. Conclusion: Fatigue was an important symptom, commonly found in MS patients, associated to some clinical factors of the disease. We didn't observe an association between fatigue and disease progression. Nevertheless, there was an association with disease severity and its duration.