Impact of autoimmune comorbidity on fatigue, sleepiness and mood in myasthenia gravis.

BACKGROUND: Disease burden in myasthenia gravis (MG) and in other autoimmune disorders is often determined by common accompanying symptoms such as fatigue, sleepiness and mood disturbances. Many MG patients have a second autoimmune disease, but it is unclear whether autoimmune comorbidities add to the severity of fatigue, sleepiness and mood disturbances. METHODS: We ascertained the presence of autoimmune comorbidities in 69 well-characterized MG patients. To assess fatigue, sleepiness and mood disturbances, we applied the Fatigue Severity Scale (FSS), the Fatigue Impact Scale (FIS), the Epworth Sleepiness Scale (ESS), as well as the Beck Depression Inventory (BDI) and State-Trait Anxiety Inventory (STAI) to all patients. RESULTS: Thirteen MG patients had concomitant autoimmune thyroid disease (AITD), including 1 patient with rheumatoid arthritis as third autoimmune disease. Fatigue (68.1%), excessive daytime sleepiness (14.5%), moderate-severe depression (20.3%) and anxiety (26.1%) were common, but MG patients with and without autoimmune comorbidities had similar FSS, FIS, ESS, BDI and STAI scores. The presence of autoimmune comorbidities was not associated with altered clinical and immunological MG characteristics, but MG patients with autoimmune comorbidities have more often been treated with corticosteroids than patients without autoimmune comorbidities (92.3% vs. 60.7%; p = 0.03). CONCLUSIONS: While many MG patients were affected by fatigue, sleepiness, depression and anxiety, the present study does not suggest that coexisting autoimmune diseases substantially contribute to the magnitude of these cumbersome comorbid symptoms. However, the higher frequency of steroid treatment may have counterbalanced the effects of the autoimmune comorbidity.

Fatigue in patients with myasthenia gravis.

BACKGROUND: The subjective feeling of fatigue in myasthenia gravis (MG) is poorly elucidated, in part because it is often confounded with the objective sign of muscle fatigability. Another reason is the paucity of validated fatigue questionnaires in MG. METHODS: We applied the 9-item Fatigue Severity Scale (FSS) and the 40-item Fatigue Impact Scale (FIS) to 73 MG patients and 230 age- and sex-matched control subjects. We ascertained levels of education, marital status, and comorbidities such as depression, sleepiness, sleep times and sleep debt. Disease severity was graded according to the Myasthenia Gravis Foundation of America (MGFA) classification. RESULTS: All fatigue scores, with the exception of the cognitive FIS subscale, were higher in MG patients than controls. In MG, the prevalence of fatigue (defined by FSS scores ≥ 4.0) was 70%. Multiple regression analyses revealed several independent associates of fatigue, including depression (all fatigue scales), MGFA stage (FSS, physical FIS), female sex (cognitive and psychosocial FIS), and sleep debt (physical FIS). CONCLUSION: Fatigue in MG is highly prevalent, mainly physical, and influenced by depressive symptoms, disease severity, female sex and sleep debt. Cognitive fatigue in MG may not be a direct disease manifestation, but secondary to depression. The FSS and FIS represent reliable and validated tools, appropriate to discern meaningful clinical aspects of fatigue in MG. Clinical recognition of the complexity of fatigue may foster individualized treatment approaches for affected MG patients.