Fatigue in the general population: A translation and test of the psychometric properties of the Norwegian version of the fatigue severity scale

Abstract

Objective: A study was undertaken to test the psychometric properties of the Fatigue Severity Scale (FSS), and to explore the relationship between fatigue and sociodemographic variables in the general population. Method: A national representative sample of 1893 respondents was randomly selected from a pool of 4,000 Norwegians aged 19—81 years. A mailed questionnaire that included the FSS was used to measure fatigue severity. Results: The FSS showed satisfactory internal consistency (Cronbach's alpha 0.88). The prevalence of high fatigue (FSS score>=5) was 23.1% in the total sample. More women (26.2%) than men (19.8%) experienced high fatigue (p=0.004). Respondents with chronic illness (more than six months) reported a higher mean (M=4.69, SD=1.35) than the rest of the sample (M=3.67, SD=1.17) (p<0.001). An inverse correlation was found between fatigue and level of formal education (r=0.20, p<0.001). Conclusion: The psychometric properties of the Norwegian version of FSS were satisfactory. To avoid over-diagnosing people for high level of fatigue, the threshold for high fatigue probably should be 5 on the FSS scale instead of 4 as had been suggested originally, but further validation of the cut-off point is needed.