title: The Chalder Fatigue Questionnaire is a valid and reliable measure of perceived fatigue severity in multiple sclerosis.
abstract: BACKGROUND
  Fatigue is one of the most distressing symptoms of multiple sclerosis (MS). Measuring MS fatigue poses a number of challenges. Many measures confound definitions of severity and impact of fatigue and/or lack psychometric validation in MS.
  
  
  OBJECTIVE
  To evaluate the psychometric properties of an 11-item fatigue severity measure, the Chalder Fatigue Questionnaire (CFQ) in MS including validity of the factor structure, internal reliability, discriminant validity and sensitivity to change.
  
  
  METHODS
  Data were pooled from four previous studies investigating MS fatigue using the CFQ (n=444). Data analysis included confirmatory factor analysis to determine the factor structure and model fit, correlations to assess discriminant validity and effects sizes to determine sensitivity to change.
  
  
  RESULTS
  A bi-factor model with one general fatigue factor, incorporating two smaller group factors (mental and physical fatigue) had good model fit and appeared the most appropriate factor structure underlying the CFQ scale. The CFQ had high internal consistency, showed small to moderate correlations with impact of fatigue and mood, and was sensitive to change across low and high intensity behavioural interventions.
  
  
  CONCLUSIONS
  The CFQ measuring a composite of physical and mental fatigue severity (i.e. a total score) is a psychometrically sound measure of fatigue severity in MS.
authors.affiliation: Health Psychology Section, Institute of Psychiatry, Psychology and Neuroscience, King's College London, UK.
authors.forename: Joseph
authors.initials: J
authors.lastname: Chilcot
authors.affiliation: Health Psychology Section, Institute of Psychiatry, Psychology and Neuroscience, King's College London, UK.
authors.forename: Sam
authors.initials: S
authors.lastname: Norton
authors.affiliation: Department of Psychosis Studies, King's College London, UK.
authors.forename: Maedhbh Etain
authors.initials: ME
authors.lastname: Kelly
authors.affiliation: Health Psychology Section, Institute of Psychiatry, Psychology and Neuroscience, King's College London, UK rona.moss-morris@kcl.ac.uk.
authors.forename: Rona
authors.initials: R
authors.lastname: Moss-Morris
mesh_terms: D000328:Adult; D005163:Factor Analysis, Statistical; D005221:Fatigue / Q000209:etiology* / Q000503:physiopathology; D005260:Female; D006801:Humans; D008297:Male; D009103:Multiple Sclerosis / Q000175:diagnosis* / Q000503:physiopathology; D010465:Perception; D011594:Psychometrics / Q000379:methods; D015203:Reproducibility of Results; D012720:Severity of Illness Index; D011795:Surveys and Questionnaires
keywords: Chalder Fatigue Questionnaire; Chalder Fatigue Scale; MS; confirmatory factor analysis; fatigue; measurement; multiple sclerosis; psychometrics