The Neurological Fatigue Index for Multiple Sclerosis (NFI-MS) is a new fatigue assessment instrument. The aim of this study was to cross-culturally adapt and assess the psychometric properties of the Brazilian version of the NFI-MS (NFI-MS/BR).
Method: Two hundred and forty subjects with MS were recruited for this study. The adaptation of the NFI-MS was performed by translation and back translation methodology. In psychometric analysis was performed the administration of the questionnaires Epworth Sleep Scale, Fatigue Severity Scale, Modified Fatigue Impact Scale, Multiple Sclerosis Impact Scale-29, NFI-MS/BR and Pittsburgh Sleep Quality Index with retest of the NFI-MS/BR after 7 days.
Results: Reliability was assessed (intraclass correlation coefficients between 0.77 and 0.86), and validity by testing 41 hypotheses about expected correlations between subscales and confirmed 36. The majority of correlations were demonstrated.
Conclusion: The NFI-MS/BR is a cross-culturally adapted, valid, and reliable instrument for assessing MS fatigue among Brazilian subjects.