Validity and Reliability of the Fatigue Severity Scale in an Adult Swedish Burn Population

Background: A burn injury is a complex trauma often followed by complications, one of which is fatigue. The objective of this study was to validate the Fatigue Severity Scale (FSS) in an adult Swedish burn cohort. Methods: A prospective cohort study was performed at the Burn Center at Uppsala University Hospital in Uppsala, Sweden. All patients who were registered for follow-up 6 months after their burn injury were asked to participate. Included patients completed questionnaires at 6 and 12 months postburn. Psychometric properties were investigated, including internal consistency (Cronbach's alpha) and concurrent validity, comparing FSS with the Brief Fatigue Inventory (BFI), which was considered to be the "gold standard." Convergent validity was investigated among the fatigue assessments and quality of life, depression/anxiety, and daily activities. Results: In total, 70 included patients attended both visits. FSS demonstrated high internal consistency (Cronbach's alpha: 0.96 at both timepoints). There was high concurrent validity between FSS and BFI on both occasions (Spearman's rho: 0.816 and 0.863, respectively), and the convergent validity was strong. Conclusions: The result indicates that the two fatigue scales correspond well to each other and that the FSS, therefore, is a valid and reliable assessment of fatigue in adult Swedish burn patients.