Fatigue, the most commonly reported symptom in patients with multiple sclerosis (MS), is associated with disease comorbidities such as depression, irritable bowel syndrome, migraine, and anxiety, according to the study “Fatigue and Comorbidities in Multiple Sclerosis,” recently published in the International Journal of MS Care.
Fatigue affects an estimated 50% to 83% of MS patients, and is considered one of the disease’s most debilitating symptoms. It can be a direct consequence of MS, due to central nervous system damage, but it can also arise from other factors that may — in some way — be related with MS. However, the impact of these associated illnesses, which are also common in MS patients, on fatigue is not fully understood.
Researchers aimed to identify physical and mental disorders that could be associated with fatigue incidence and changes over time in MS patients. The study recruited 949 MS patients from four Canadian centers, who were evaluated at three visits over the course of two years, where changes in fatigue and comorbidities were assessed.
At baseline, 21.8% of the patients did not report fatigue, 24.1% had mild fatigue, 27.3% moderate fatigue, and 26.1% severe fatigue. Furthermore, in individuals reporting at least one comorbidity, 84.5% said they suffered from fatigue, compared with 66.8% of patients without associated illnesses.
Over the course of the study, the incidence of fatigue was determined to be 38.8%. The prevalence of fatigue at the study’s start was associated with time since symptom onset, age, and high degree of disability, as assessed by the EDSS test.
Fatigue was also found to be associated with depression: patients with no current depressive symptoms but a history of depression had an odds of reporting fatigue 3.38-fold higher than patients with no history of depression. This value increased to 9.94 in patients with current depressive symptoms and no history of depression, and 10.82 in those with symptoms and a history of depression. The authors also found that depression at baseline was associated with worse fatigue over time.
After adjusting the results for disease duration, disability status, age, sex, and educational level, four comorbidities — anxiety, irritable bowel syndrome (IBS), depression, and migraine — were each independently associated with increased odds of fatigue that persisted over time.
“We confirmed that depression is associated with fatigue, but we also showed that there is a differential effect of a history of depression and current depressive symptom severity on fatigue, as well as that depression increases the risk of worsening fatigue over a 2-year period,” the authors wrote, and again noted the comorbidites also “found to be associated with persistent fatigue.” Addressing these conditions, they said, “may offer some means of reducing fatigue in MS.”