Psychometric properties of the fatigue questionnaire EORTC QLQ-FA12 and proposal of a cut-off value for young adults with cancer

BACKGROUND: Young adult patients with cancer have to deal with their disease in an eventful phase of life. A common side effect of cancer and its treatment is cancer-related fatigue (CRF), a phenomenon which can thwart successful coping with developmental tasks. The aims of this study were to assess the psychometric properties of the EORTC QLQ-FA12, a new instrument for assessing physical, emotional and cognitive fatigue, in young adults with cancer, and to propose a cut-off value that indicates a need for further more specific diagnostics. METHODS: In a sample of young adults who were first diagnosed with cancer between the ages of 18 and 39 years old, we assess the composite and item reliabilities as well as discriminant validity of the subscales for the EORTC QLQ-FA12. We also discuss two possible ways to calculate a summarizing score when conducting a receiver operating characteristic (ROC) analysis to find the cut-off value. RESULTS: The EORTC QLQ-FA12 fit the sample (CFI = 0.96, SRMR = 0.04), had discriminant validity regarding its subscales and every subscale showed convergent validity (composite reliabilities were 0.92 for physical, 0.89 for emotional and 0.74 for cognitive fatigue). The sum of the first ten items with a range of 0 to 30 revealed a cut-off value of twelve or more with 91% sensitivity and 77% specificity. CONCLUSION: The new instrument EORTC QLQ-FA12 is able to distinguish between physical, emotional, and cognitive fatigue in young adult patients. It enables us to study different concepts of general fatigue without the need for additional items, and can be used as a screening instrument for young adults. Future research should investigate the multidimensional character of CRF. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (10.1186/s12955-018-0949-0) contains supplementary material, which is available to authorized users.