Health-related quality of life in cancer patients at the end of life, translation, validation, and longitudinal analysis of specific tools: study protocol for a randomized controlled trial

BACKGROUND: The end of life for cancer patients is the ultimate stage of the disease, and care in this setting is important as it can improve the wellbeing not only of patients, but also the patients' family and close friends. As it is a matter of profoundly personal concerns, patients' perception of this phase of the disease is difficult to assess and has thus been insufficiently studied. Nonetheless, caregivers are required to provide specific care to help patients and to treat them in order to improve their wellbeing during this period. While tools to assess health-related quality of life (QoL) in cancer patients at the end of life exist in English, to our knowledge, no validated tools are available in French. METHODS/DESIGN: This randomized multicenter cohort study will be carried out to cross-culturally adapt and validate a French version of the English QUAL-E and the Missoula Vitas Quality Of Life Index (MVQOLI) questionnaires for advanced cancer patients in a palliative setting. A randomized clinical trial component in addition to a cohort study is implemented in order to test psychometric hypotheses: order effect and improvement of sensibility to change. The validation procedure will ensure that the psychometric properties are maintained. The main criterion to assess the reliability of the questionnaires will be reproducibility (test-retest method) using intraclass correlation coefficients. It will be necessary to include 372 patients. The sensitivity to change, discriminant capability as well as convergent validity will be also investigated. DISCUSSION: If the cross-cultural validation of the MVQOLI and QUAL-E questionnaires for advanced cancer patients in a palliative setting have satisfactory psychometric properties, it will allow us to assess the specific dimensions of QoL at the end of life. TRIAL REGISTRATION: Current Controlled Trials NCT01545921.