Single-arm studies involving patient-reported outcome data in oncology: a literature review on current practice

Patient-reported outcomes (PROs) are increasingly used in single-arm cancer studies. We reviewed 60 recent publications of single-arm studies of cancer treatment involving PRO data for current practice on design, analysis, reporting, and interpretation. We further examined their handling of potential bias and how they informed decision-making. Most studies (97%) analyzed PROs without stating a predefined research hypothesis. Thirteen studies (22%) used a PRO as a (co)primary endpoint. Definitions of PRO objectives, study population, endpoints, and strategies of handling missing data varied widely. Twenty-three studies (38%) compared the PRO data to external information, most often by using a clinically important difference value; one study used a historical control group. Appropriateness of methods to handle missingness and intercurrent events including death were seldom discussed. Most studies (85%) concluded that PRO results supported treatment. Conducting and reporting of PROs in cancer single-arm studies lacks standards, and a critical discussion of statistical methods and possible biases. These findings will guide the Setting International Standards in Analysing Patient-Reported Outcomes and Quality of Life Data in Cancer Clinical Trials-Innovative Medicines Initiative (SISAQOL-IMI) in developing recommendations for the use of PRO-measures in single arm studies.