title: Validation of a Dutch version of the Neurological Fatigue Index (NFI-MS) for patients with multiple sclerosis in the Netherlands.
abstract: OBJECTIVE
  Fatigue is a complex, multidimensional construct. Most questionnaires measuring fatigue do not meet the standards for good measurement properties. Therefore, the Neurological Fatigue Index for multiple sclerosis (NFI-MS) is recently developed using thorough methods. The aim of this study was to develop and validate the Dutch version of the NFI-MS.
  
  
  METHODS
  The original English version of the NFI-MS was translated into Dutch using a forward-backward procedure. Reliability (intraclass correlation coefficient (ICC) and standard error of measurement (SEM)) were assessed for the summary score and the four subscale scores separately. Construct validity was assessed by testing hypotheses about expected correlations between the NFI-MS and other constructs (e.g. impact on functioning and depression) and expected differences on NFI scores between groups defined on the basis of disease type and work status.
  
  
  RESULTS
  The reliability analyses (n = 118) showed that the ICC was 0.78 (NFI-MS summary) and ranged from 0.75 to 0.83 for the four subscales and the SEM was 2.5 (NFI-MS summary) and ranged from 1.1 to 2.2 for the four subscales. For construct validity (n = 136), 50 out of the 57 expected hypotheses were confirmed (88 %).
  
  
  CONCLUSIONS
  The present study shows that the Dutch version of the NFI-MS is a reliable and valid self-report questionnaire for measuring fatigue in Dutch patients with MS.
authors: Department of Epidemiology and Biostatistics, VU University Medical Center (VUmc), De Boelelaan 1118, 1081 HZ, Amsterdam, The Netherlands.
authors: Arthur
authors: A
authors: Derksen
authors: Lidwine B
authors: LB
authors: Mokkink
authors: Marc B
authors: MB
authors: Rietberg
authors: Dirk L
authors: DL
authors: Knol
authors: Raymond W J G
authors: RW
authors: Ostelo
authors: Bernard M J
authors: BM
authors: Uitdehaag
mesh_terms: D000328:Adult; D000368:Aged; D005221:Fatigue / Q000145:classification* / Q000209:etiology; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009103:Multiple Sclerosis / Q000150:complications / Q000503:physiopathology*; D009426:Netherlands; D011594:Psychometrics / Q000295:instrumentation*; D011788:Quality of Life; D015203:Reproducibility of Results; D011795:Surveys and Questionnaires