LAUSR

Background: The aim of this study was to translate and validate the Functional Assessment of Chronic illnesses Therapy-Fatigue (FACIT-fatigue subscale) in Iran. Methods: The Persian version of the FACIT-fatigue scale was developed using the forward-backward translation method. The questionnaire was then presented to a consecutive sample of breast cancer patients (n = 208) attending the Iranian Center of Breast Cancer (ICBC). The reliability was assessed by internal consistency and test-retest using Cronbach's α and intraclass correlation coefficient (ICC), respectively. Convergent validity was examined by correlation between the FACIT-fatigue scale and the Hospital and Depression Scale (HADS). In addition, discriminant validity was evaluated by the ability of the scale to differentiate between patients who differed in disease stage. Results: The internal consistency of the questionnaire was excellent (Cronbach's α = 0.92). The ICC for the FACIT-fatigue was 0.84. Strong correlations were observed between FACIT-fatigue and depression (r = -0.69) and anxiety (r = -0.72) scores. The FACIT-fatigue discriminated well between subgroups of patients who differed in stage (p < 0.001) and probable caseness of anxiety and depression disease (p < 0.001). Conclusion: The Iranian version of the FACIT-fatigue subscale is a valid and reliable instrument to measure fatigue in cancer patients.