Assessing fatigue in children and adolescents: Psychometric validation of the German version of the PROMIS(®) Pediatric Short Form v2.0 - Fatigue 10a in school children and pediatric chronic pain patients

PURPOSE: Fatigue is a common symptom in children and adolescents. Its negative impact on health outcomes is even more pronounced in those with chronic pain. There is currently no fatigue measurement tool in German that is validated for both children and adolescents with and without chronic pain. Therefore, this study aimed to gather quantitative validity evidence to support the use of the German version of the PROMIS(®) Pediatric Short Form v2.0 - Fatigue 10a (PROMIS(®) F-SF) in the German pediatric general population as well as in German pediatric chronic pain patients. METHODS: The 10-item self-assessment questionnaire was validated in a sample of N = 1348 school children (9–18 years; 52.4% female) and N = 114 pediatric chronic pain patients (8–17 years; 63.3% female). Construct and convergent validity, reliability, and item and scale characteristics were examined. RESULTS: Confirmatory factor analyses showed sufficient model fit for the 1-factor model of the questionnaire (school sample: CFI = 0.94, RMSEA = 0.10, SRMR = 0.04; patient sample: CFI = 0.90, RMSEA = 0.14, SRMR = 0.05). Convergent validity was supported by weak-to-large significant correlations with sleep quality, health-related quality of life (HRQoL), and pain characteristics. The questionnaire had excellent internal consistency in both samples (α = 0.92 and α = 0.93). Sex differences and age distributions of the PROMIS(®) F-SF showed that girls reported significantly higher fatigue than boys and that fatigue increased with age. CONCLUSION: The PROMIS(®) F-SF is a reliable instrument with good psychometric properties. Preliminary evidence is provided that the questionnaire validly measures fatigue in children and adolescents with and without chronic pain. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s11136-021-03032-8.