A prospective study of patterns of fatigue in Multiple Sclerosis

Abstract

We sought to identify clinical characteristics and socio-demographic variables associated with longitudinal patterns of fatigue in MS patients. A questionnaire including the Fatigue Severity Scale (FSS) was mailed to a community sample of 502 MS patients three times one year apart. Three patterns of fatigue were defined: persistent fatigue (PF) (mean FSS-score ≥5 at all time-points), sporadic fatigue (SF) (mean FSS-score ≥5 at one or two time-points) and no fatigue (mean FSS-score <5 at all time-points). Among the 267 (53%) patients who responded at all time points, 101 (38%, 95%CI 32-44) had persistent, 98 (37%, 95CI 31-43) sporadic and 68 (25%, 95%CI 20-31) no fatigue. Persistent and sporadic fatigue were more common in patients with, increased neurological impairment (p<0.001), primary progressive MS (p=0.01), insomnia (p<0.001), heat sensitivity (p<0.001), sudden-onset fatigue (p<0.001) or mood disturbance (p<0.001) compared to patients without fatigue. Multivariable analysis showed that depression (PF p=0.02, SF p<0.001), heat sensitivity (PF p=0.04, SF p=0.02), and physical impairment (PF p=0.004, SF p=0.01) were associated with both sporadic and persistent fatigue. 75% of the patients had persistent or sporadic fatigue over a two years observation period. Multivariable analyses confirmed a significant association between levels of depression, physical impairment and persistent fatigue.