Cross cultural adaptation and psychometric evaluation of an Arabic version of the modified fatigue impact scale in people with multiple sclerosis

BACKGROUND: Fatigue is a common symptom in multiple sclerosis and has significant impacts on participation and quality of life. Thus, fatigue assessment in this population is always a necessity. OBJECTIVES: to examine the underlying structure, validity and test-retest reliability of an Arabic translated and culturally adapted version of the Modified Fatigue Impact scale (A-MFIS). METHODS: The study was carried out into two phases: firstly, the English version of the MFIS was translated into Arabic and secondly, a detailed analysis of the psychometric properties and the structure of the translated version was conducted using Principle Component Analysis (PCA). Convergent validity was assessed by comparison with measures of disease severity, quality of life and with another measure of fatigue. Test retest reliability was assessed with intra-class correlations. RESULTS: 145 subjects participated in the study. The PCA revealed that the instrument has two main factors "cognitive" and "physical", rather than the original three factors scale. Significant correlations were found between the A-MFIS and measures of disease severity and quality of life (P