Purpose: To understand the consequences of diseases and treatment such as cancer and thus the needs of patients for surveillance and care and to improve quality of life, patients should be assessed using a holistic approach. However, instruments to create such a holistic view do not exist and the development presents unique challenges. Therefore, this study presents a method for the development of a holistic assessment questionnaire using cancer-related fatigue (CRF) as a case.

Method: We started with (1) the definition of our construct of interest (CRF) on the theme level followed by (2) item selection, an iterative process of searching for validated questionnaires that together cover the full holistic construct. The construct definition on theme level (1) was too broad and was, therefore, redefined on the element level (construct > theme > element) based on interviews with relevant stakeholders. Hereafter, item selection (2) was performed on the element level based on a priority list, psychometric properties (e.g., discriminative parameter value) and consultation of experts and future users. Lastly, (3) items were reformulated.

Results: Initial CRF construct definition (1) resulted in 110 relevant validated questionnaires with over three thousand items, requiring a construct redefinition on element level. Seventy-two items from 21 validated questionnaires were included (2) in the preliminary holistic assessment questionnaire. For item reformulation (3), easy language was used to better suit the target population.

Conclusion: Tailoring care to the individual requires a holistic view. This article presents a novel method to develop a holistic assessment questionnaire, including an example for CRF, with several recommendations for cancer-specific instrument development. Although the development process of a holistic assessment questionnaire is time-consuming, more late and long-term effects of cancer are multidimensional and could benefit from a holistic approach in their assessment to enable personalised care, thereby improving quality of life and reducing societal impact.