Development of a Disease-Specific Health-Related Quality of Life Questionnaire (DTF-QoL) for Patients with Desmoid-Type Fibromatosis

Simple Summary Desmoid-type fibromatosis (DTF) is an uncommon soft-tissue tumour that is incapable of metastasising. Patients can experience a variety of physical and psychological symptoms, making assessment of health-related quality of life (HRQoL) highly relevant. Measuring the impact of DTF on HRQoL can be challenging due to the rare character and variable clinical presentation of the disease. Therefore, a HRQoL instrument assessing DTF-specific issues is needed. Previously, a provisional DTF-specific HRQoL tool was developed (the DTF-QoL). The aim of the current study was to pre-test the DTF-QoL. Pre-testing of the questionnaire led to the selection of 96 questions, conceptualised into three symptom subscales, eleven disease-impact subscales and six single items, together forming the final DTF-QoL. This questionnaire can be used in both clinical and research settings to evaluate HRQoL of DTF patients, which could help to provide personalised care and improve overall patient experience. Sporadic desmoid-type fibromatosis (DTF) is a rare, non-metastasising soft-tissue tumour. Patients can experience a variety of disease-specific issues related to the unpredictable clinical course and aggressiveness of DTF, which negatively impacts health-related quality of life (HRQoL). These DTF-specific issues are not captured by generic HRQoL tools. A 102-item provisional DTF-specific HRQoL tool, the DTF-QoL, was previously developed. The aim of this study was to pre-test the psychometric properties of the DTF-QoL by administering it together with the EORTC Quality of Life Questionnaire Core 30 (EORTC QLQ-C30) to 236 DTF patients from the United Kingdom and the Netherlands. Construct validity and reliability were determined based on factor analysis, multi-trait scaling analysis, Cronbach's alpha, and correlations with the EORTC QLQ-C30 scales. Ninety-six items were selected, conceptualised into three symptom scales, eleven disease-impact scales and six single items, together forming the final DTF-QoL. Scaling assumptions were fully or moderately met for ten out of fourteen scales. Cronbach's alpha ranged from 0.551-0.908. Most scales of the DTF-QoL were weakly or moderately correlated with the EORTC QLQ-C30. The DTF-QoL is a promising tool capturing the whole spectrum of DTF-specific issues. Implementation of the DTF-QoL in research and clinical practice will help to personalise HRQoL measurement and clinical care for DTF patients.