Cross-cultural adaptation and validation of the universal Portuguese-version of the Pediatric Functional Assessment of Chronic Illness Therapy – Fatigue (pedsFACIT-F)()

OBJECTIVE: To cross-culturally adapt and validate the universal Portuguese version of the Pediatric Functional Assessment of Chronic Illness Therapy – Fatigue (pedsFACIT-F). METHOD: The universal Portuguese version of the pedsFACIT-F was cross-culturally adapted and validated in 323 children and adolescents aged 8–18 years, 173 healthy individuals, and 150 with chronic diseases (cancer, juvenile idiopathic arthritis, and diabetes). Reliability (internal consistency and test–retest reliability) was assessed. Item response theory model assumptions were evaluated using confirmatory and exploratory factor analyses. Items were calibrated using a graded response model. Differential item functioning was assessed regarding age, gender, and clinical condition (healthy vs. chronic diseases). RESULTS: No major cultural adaptations were needed. Internal consistency (Cronbach's alpha = 0.84) and test–retest reliability (intraclass correlation coefficient = 0.92) were good. CFA (CFI = 0.92, TLI = 0.90, RMSEA = 0.097) and CFE analysis confirmed sufficient unidimensionality. The data also fit the GRM and demonstrated good coverage of the fatigue construct (threshold parameters range: −1.42 to 4.56). No items demonstrated significant differential item functioning. CONCLUSION: The universal Portuguese version of the pedsFACIT-F provides a reliable, precise, and valid measure after being assessed by robust psychometric properties. Stability of the measurement properties of the pedsFACIT-F scale allows its use to assess fatigue in clinical research in Portuguese-speaking children and adolescents.