Objectives: To evaluate the psychometric properties of the Norwegian version of the multidimensional fatigue inventory (MFI-20) in patients with inflammatory bowel disease.
Methods: Participants were recruited from nine hospitals in the southeastern and western parts of Norway. Clinical and sociodemographic data were collected, and participants completed the MFI-20, as well as the Fatigue Questionnaire (FQ). In addition to a confirmatory factor analysis, validity, reliability, test-retest and responsiveness were evaluated.
Results: In total, 410 patients were included. The Norwegian MFI-20 had an acceptable model fit when compared to the original five-dimensional structure. A positive correlation was observed between the dimensions of MFI-20 and the FQ. MFI-20 scores increased according to subjective disease activity, but no differences were observed when using a calprotectin cut-off < or > =250 µg/g mg/kg. All MFI-20 dimensions except 'reduced motivation' in both ulcerative colitis (UC) and Crohn's disease (CD) patients had alpha Cronbach alpha values ≥70, and test-retest reliability revealed good to excellent values. Merely one dimension (Reduced activity) in UC patients reporting improvement did not reach the threshold for acceptable responsiveness according to Guyatt statistics.
Conclusions: The Norwegian version of MFI-20 is valid, reliable and responsive. The instrument can safely be used in studies using fatigue as an endpoint.
Keywords: Inflammatory bowel disease; fatigue; multidimensional fatigue inventory; psychometrical testing.