The Silhouettes Fatigue Scale: further validation in Spanish-speaking university students and adults with chronic pain

Purpose: The aim of this study was to evaluate the psychometric properties of the Silhouettes Fatigue Scale (SFS) when used to assess fatigue in undergraduates and middle-aged adults with chronic pain. Materials and methods: A total of 426 undergraduates and 207 middle-aged individuals with chronic pain participated in this study. Participants were asked to respond to a survey including the SFS as well as another validated measure of fatigue, questionnaires about pain catastrophizing and pain interference, and questions about pain (i.e., location, duration, and intensity). Convergent, discriminant, criterion and known-groups validity were evaluated. Results: Convergent validity was supported by a strong association between the two scales measuring fatigue. Discriminant validity was supported by stronger associations between the two fatigue scales scores compared to those between the SFS and pain catastrophizing scores. Criterion validity was supported by moderate associations between the SFS and measures of pain intensity and pain interference. Finally, known-groups validity was supported by significant differences in the SFS scores between students without chronic pain, students with chronic pain, and middle-aged individuals with chronic pain. Conclusions: The findings support the validity of the SFS scores when used to assess fatigue in undergraduates and middle-aged adults with chronic pain.