Validation of the Portuguese version of Functional Assessment of Cancer Therapy-Fatigue (FACT-F) in Brazilian cancer patients

Abstract

The purpose of this study was to validate the Portuguese version of the Functional Assessment of Cancer Therapy-Fatigue (FACT-F) in order to establish its assessment properties, including validity and reliability in a sample of Brazilian cancer patients. Two hundred seventy patients with different types of cancer were included for this study; the mean age was 50.5 years. The reliability was assessed by internal consistency and reproducibility. Construct validity was assessed through convergent validity and discriminant validity. Convergent validity was examined by comparing the FACT-F to the SF-36. Discriminant validity of the FACT-F evaluated the ability of the scale to differentiate defined groups, discriminating patients according to Eastern Cooperative Oncology Group Performance Status and different stages of disease. FACT-F had high internal consistency (Cronbach alpha coefficient was 0.78 for physical well-being, 0.68 for social/family well-being, 0.75 for emotional well-being, 0.74 for functional well-being, 0.91 for fatigue, and 0.92 for total FACT-F). The range of test-retest intraclass correlation was from 0.72 to 0.91 (p < 0.0001). The Pearson product correlation revealed good correlations between the total FACT-F and subscales of the SF-36 in most dimensions, ranging from r = 0.51 to r = 0.76, except for SF-36 physical (r = 0.31). The positive correlations between the SF-36 vitality scale and FACT-F total (r = 0.76) and the fatigue subscale (r = 0.77) support the convergent validity. The Portuguese version of FACT-F is a reliable and valid instrument to assess quality of life and fatigue, representing a valid tool to screen cancer-related fatigue in Brazilian cancer patients.