title: Fatigue and Comorbidities in Multiple Sclerosis.
abstract: BACKGROUND
  Fatigue is commonly reported by people with multiple sclerosis (MS). Comorbidity is also common in MS, but its association with the presence of fatigue or fatigue changes over time is poorly understood.
  
  
  METHODS
  Nine hundred forty-nine people with definite MS were recruited from four Canadian centers. The Fatigue Impact Scale for Daily Use and a validated comorbidity questionnaire were completed at three visits over 2 years. Participants were classified into groups with no fatigue versus any fatigue. Logistic regression was used to determine the relationship between fatigue and each comorbidity at baseline, year 1, year 2, and overall.
  
  
  RESULTS
  The incidence of fatigue during the study was 38.8%. The prevalence of fatigue was greater in those who were older (P = .0004), had a longer time since symptom onset (P = .005), and had greater disability (P < .0001). After adjustment, depression (odds ratio [OR], 2.58; 95% confidence interval [CI], 2.03-3.27), irritable bowel syndrome (OR, 1.71; 95% CI, 1.18-2.48), migraine (OR, 1.69; 95% CI, 1.27-2.27), and anxiety (OR, 1.57; 95% CI, 1.15-2.16) were independently associated with fatigue that persisted during the study. There was also an individual-level effect of depression on worsening fatigue (OR, 1.49; 95% CI, 1.08-2.07).
  
  
  CONCLUSIONS
  Comorbidity is associated with fatigue in MS. Depression is associated with fatigue and with increased risk of worsening fatigue over 2 years. However, other comorbid conditions commonly associated with MS are also associated with persistent fatigue, even after accounting for depression. Further investigation is required to understand the mechanisms by which comorbidities influence fatigue.
authors.affiliation: Department of Internal Medicine, College of Medicine, Faculty of Health Sciences (KMF, RAM), and Department of Community Health Sciences, College of Medicine (RAM), University of Manitoba, Winnipeg, MB, Canada; Departments of Psychiatry, Medicine, Psychology, and Neuroscience, Dalhousie University, Halifax, NS, Canada (JDF); Departments of Psychiatry and Community Health Sciences, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada (SBP); Division of Neurology, Faculty of Medicine (HT), and Department of Experimental Medicine (KAM), University of British Columbia, Vancouver, BC, Canada; Departments of Epidemiology and Biostatistics, Occupational Health, and Medicine, McGill University, Montreal, QC, Canada (CW); Faculty of Rehabilitation Medicine, University of Alberta, Edmonton, AB, Canada (SW); and Department of Psychology, St. Francis Xavier University, Antigonish, NS, Canada (LIB).
authors.forename: Kirsten M
authors.initials: KM
authors.lastname: Fiest
authors.affiliation: Department of Internal Medicine, College of Medicine, Faculty of Health Sciences (KMF, RAM), and Department of Community Health Sciences, College of Medicine (RAM), University of Manitoba, Winnipeg, MB, Canada; Departments of Psychiatry, Medicine, Psychology, and Neuroscience, Dalhousie University, Halifax, NS, Canada (JDF); Departments of Psychiatry and Community Health Sciences, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada (SBP); Division of Neurology, Faculty of Medicine (HT), and Department of Experimental Medicine (KAM), University of British Columbia, Vancouver, BC, Canada; Departments of Epidemiology and Biostatistics, Occupational Health, and Medicine, McGill University, Montreal, QC, Canada (CW); Faculty of Rehabilitation Medicine, University of Alberta, Edmonton, AB, Canada (SW); and Department of Psychology, St. Francis Xavier University, Antigonish, NS, Canada (LIB).
authors.forename: John D
authors.initials: JD
authors.lastname: Fisk
authors.affiliation: Department of Internal Medicine, College of Medicine, Faculty of Health Sciences (KMF, RAM), and Department of Community Health Sciences, College of Medicine (RAM), University of Manitoba, Winnipeg, MB, Canada; Departments of Psychiatry, Medicine, Psychology, and Neuroscience, Dalhousie University, Halifax, NS, Canada (JDF); Departments of Psychiatry and Community Health Sciences, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada (SBP); Division of Neurology, Faculty of Medicine (HT), and Department of Experimental Medicine (KAM), University of British Columbia, Vancouver, BC, Canada; Departments of Epidemiology and Biostatistics, Occupational Health, and Medicine, McGill University, Montreal, QC, Canada (CW); Faculty of Rehabilitation Medicine, University of Alberta, Edmonton, AB, Canada (SW); and Department of Psychology, St. Francis Xavier University, Antigonish, NS, Canada (LIB).
authors.forename: Scott B
authors.initials: SB
authors.lastname: Patten
authors.affiliation: Department of Internal Medicine, College of Medicine, Faculty of Health Sciences (KMF, RAM), and Department of Community Health Sciences, College of Medicine (RAM), University of Manitoba, Winnipeg, MB, Canada; Departments of Psychiatry, Medicine, Psychology, and Neuroscience, Dalhousie University, Halifax, NS, Canada (JDF); Departments of Psychiatry and Community Health Sciences, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada (SBP); Division of Neurology, Faculty of Medicine (HT), and Department of Experimental Medicine (KAM), University of British Columbia, Vancouver, BC, Canada; Departments of Epidemiology and Biostatistics, Occupational Health, and Medicine, McGill University, Montreal, QC, Canada (CW); Faculty of Rehabilitation Medicine, University of Alberta, Edmonton, AB, Canada (SW); and Department of Psychology, St. Francis Xavier University, Antigonish, NS, Canada (LIB).
authors.forename: Helen
authors.initials: H
authors.lastname: Tremlett
authors.affiliation: Department of Internal Medicine, College of Medicine, Faculty of Health Sciences (KMF, RAM), and Department of Community Health Sciences, College of Medicine (RAM), University of Manitoba, Winnipeg, MB, Canada; Departments of Psychiatry, Medicine, Psychology, and Neuroscience, Dalhousie University, Halifax, NS, Canada (JDF); Departments of Psychiatry and Community Health Sciences, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada (SBP); Division of Neurology, Faculty of Medicine (HT), and Department of Experimental Medicine (KAM), University of British Columbia, Vancouver, BC, Canada; Departments of Epidemiology and Biostatistics, Occupational Health, and Medicine, McGill University, Montreal, QC, Canada (CW); Faculty of Rehabilitation Medicine, University of Alberta, Edmonton, AB, Canada (SW); and Department of Psychology, St. Francis Xavier University, Antigonish, NS, Canada (LIB).
authors.forename: Christina
authors.initials: C
authors.lastname: Wolfson
authors.affiliation: Department of Internal Medicine, College of Medicine, Faculty of Health Sciences (KMF, RAM), and Department of Community Health Sciences, College of Medicine (RAM), University of Manitoba, Winnipeg, MB, Canada; Departments of Psychiatry, Medicine, Psychology, and Neuroscience, Dalhousie University, Halifax, NS, Canada (JDF); Departments of Psychiatry and Community Health Sciences, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada (SBP); Division of Neurology, Faculty of Medicine (HT), and Department of Experimental Medicine (KAM), University of British Columbia, Vancouver, BC, Canada; Departments of Epidemiology and Biostatistics, Occupational Health, and Medicine, McGill University, Montreal, QC, Canada (CW); Faculty of Rehabilitation Medicine, University of Alberta, Edmonton, AB, Canada (SW); and Department of Psychology, St. Francis Xavier University, Antigonish, NS, Canada (LIB).
authors.forename: Sharon
authors.initials: S
authors.lastname: Warren
authors.affiliation: Department of Internal Medicine, College of Medicine, Faculty of Health Sciences (KMF, RAM), and Department of Community Health Sciences, College of Medicine (RAM), University of Manitoba, Winnipeg, MB, Canada; Departments of Psychiatry, Medicine, Psychology, and Neuroscience, Dalhousie University, Halifax, NS, Canada (JDF); Departments of Psychiatry and Community Health Sciences, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada (SBP); Division of Neurology, Faculty of Medicine (HT), and Department of Experimental Medicine (KAM), University of British Columbia, Vancouver, BC, Canada; Departments of Epidemiology and Biostatistics, Occupational Health, and Medicine, McGill University, Montreal, QC, Canada (CW); Faculty of Rehabilitation Medicine, University of Alberta, Edmonton, AB, Canada (SW); and Department of Psychology, St. Francis Xavier University, Antigonish, NS, Canada (LIB).
authors.forename: Kyla A
authors.initials: KA
authors.lastname: McKay
authors.affiliation: Department of Internal Medicine, College of Medicine, Faculty of Health Sciences (KMF, RAM), and Department of Community Health Sciences, College of Medicine (RAM), University of Manitoba, Winnipeg, MB, Canada; Departments of Psychiatry, Medicine, Psychology, and Neuroscience, Dalhousie University, Halifax, NS, Canada (JDF); Departments of Psychiatry and Community Health Sciences, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada (SBP); Division of Neurology, Faculty of Medicine (HT), and Department of Experimental Medicine (KAM), University of British Columbia, Vancouver, BC, Canada; Departments of Epidemiology and Biostatistics, Occupational Health, and Medicine, McGill University, Montreal, QC, Canada (CW); Faculty of Rehabilitation Medicine, University of Alberta, Edmonton, AB, Canada (SW); and Department of Psychology, St. Francis Xavier University, Antigonish, NS, Canada (LIB).
authors.forename: Lindsay I
authors.initials: LI
authors.lastname: Berrigan
authors.affiliation: Department of Internal Medicine, College of Medicine, Faculty of Health Sciences (KMF, RAM), and Department of Community Health Sciences, College of Medicine (RAM), University of Manitoba, Winnipeg, MB, Canada; Departments of Psychiatry, Medicine, Psychology, and Neuroscience, Dalhousie University, Halifax, NS, Canada (JDF); Departments of Psychiatry and Community Health Sciences, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada (SBP); Division of Neurology, Faculty of Medicine (HT), and Department of Experimental Medicine (KAM), University of British Columbia, Vancouver, BC, Canada; Departments of Epidemiology and Biostatistics, Occupational Health, and Medicine, McGill University, Montreal, QC, Canada (CW); Faculty of Rehabilitation Medicine, University of Alberta, Edmonton, AB, Canada (SW); and Department of Psychology, St. Francis Xavier University, Antigonish, NS, Canada (LIB).
authors.forename: Ruth Ann
authors.initials: RA
authors.lastname: Marrie