title: Measuring fatigue in polio survivors: content comparison and reliability of the Fatigue Severity Scale and the Checklist Individual Strength.
abstract: OBJECTIVE
  To compare the content of the Fatigue Severity Scale and the subscale "subjective experience of fatigue" of the Checklist Individual Strength, and (ii) to assess the reliability of both questionnaires in polio survivors.
  
  
  METHODS
  Repeated-measures at a 3-week interval.
  
  
  METHODS
  Consecutive series of 61 polio survivors.
  
  
  METHODS
  Concepts contained in the questionnaire items were linked to the International Classification of Functioning, Disability and Health (ICF), using standardized linking rules. Reliability analyses included tests of internal consistency, test-retest reliability and measurement error.
  
  
  RESULTS
  Questionnaires differed in the extent to which they measured other than fatigue-related aspects of functioning (represented ICF components: "Body functions": 50% and 80%, "Activities and Participation": 30% and 0%, for the Fatigue Severity Scale and Checklist Individual Strength, respectively). Internal consistency and test-retest reliability were considered acceptable, while measurement error was large (Cronbach's α: 0.90 and 0.93, intraclass correlation coefficient: 0.80 and 0.85, smallest detectable change: 28.7% and 29.4% for the Fatigue Severity Scale and Checklist Individual Strength, respectively).
  
  
  CONCLUSIONS
  Considering the acceptable clinimetric properties, we conclude that both the Fatigue Severity Scale and the Checklist Individual Strength can be applied in research on post-poliomyelitis syndrome when measuring fatigue. However, because the 2 questionnaires differ in content they cannot be used interchangeably.
authors.affiliation: Department of Rehabilitation , Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands. s.koopman@amc.uva.nl.
authors.forename: Fieke S
authors.initials: FS
authors.lastname: Koopman
authors.forename: Merel A
authors.initials: MA
authors.lastname: Brehm
authors.forename: Yvonne F
authors.initials: YF
authors.lastname: Heerkens
authors.forename: Frans
authors.initials: F
authors.lastname: Nollet
authors.forename: Anita
authors.initials: A
authors.lastname: Beelen
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D057189:Checklist / Q000592:standards*; D005221:Fatigue / Q000175:diagnosis* / Q000209:etiology / Q000523:psychology; D005260:Female; D006801:Humans; D064702:International Classification of Functioning, Disability and Health; D008297:Male; D008875:Middle Aged; D053580:Muscle Strength / Q000502:physiology; D009426:Netherlands; D016262:Postpoliomyelitis Syndrome / Q000150:complications*; D015203:Reproducibility of Results; D012720:Severity of Illness Index; D011795:Surveys and Questionnaires; D017741:Survivors