Fatigue in multiple sclerosis: relationship to depression, disability, anddisease pattern

In order to investigate the associations between fatigue and depression, di sability, and disease subtype, 207 individuals with clinically definite Mul tiple Sclerosis (MS) were administered the Fatigue Severity Scale and the Z ung Self-rating Depression Scale during a regular clinic appointment Their current level of disability was established using the Expanded Disability S tatus Scale. Fatigue and depression were highly correlated (r=0.58), even w hen the depression measure was corrected for items overlapping with fatigue and other symptoms or consequences of MS (r=0.44). Fatigue and disability were also correlated (r=0.33). Multiple regression revealed that both depre ssed mood and disability were significant predictors of fatigue, together a ccounting for approximately 23% of the variance in patients' self-reported fatigue. The combined groups of primary Progressive (n=45) and secondary Pr ogressive patients (n=25) appeared to have higher fatigue scores than relap sing-remitting patients (n=137). However, on analysis of covariance reveale d that this apparent difference was in fact attributable almost exclusively To differences in disability among the three subtypes of MS. Other reports of differences in fatigue between subtypes of MS should be re-examined in light of this finding.