Patient-reported outcomes (PRO) data can deliver crucial information for diagnostic purposes and regarding benefits and possible harms of medical interventions. Recognising the potential of the patient’s voice, PRO data are increasingly integrated in clinical practice and clinical research, and they play an increasingly important role in medical and health policy decision making. With the growing focus on patient centeredness, the requirements towards the quality of PRO data are steadily increasing as well, and outcomes researchers and other stakeholders working in related disciplines such as academia, the pharmaceutical industry and the not-for-profit sector have a growing ethical responsibility to use only those PRO instruments that generate robust data and allow for valid inferences from PRO scores. To achieve high quality PRO data, standardised processes spanning from PRO instrument development and content validation, translation and cultural adaptation, statistical analysis and interpretation of PRO data are key to ensure that data collected via patient self-report can be trusted. This habilitation thesis focuses on PRO standardisation efforts worldwide, including an overview of PRO projects that were run in the context of two key PRO measurement systems, i.e., the PRO instruments of 1) the Patient-Reported Outcomes Measurement Information System (PROMIS) initiative and 2) the European Organization for Research and Treatment of Cancer (EORTC) Quality of Life Group. In conclusion, international initiatives aimed at standardised PRO assessment are well underway all of which contribute to ensuring that high quality PRO data can be generated. It is expected that both the PROMIS and EORTC suites of PRO instruments will continue to grow, consolidate the PRO field and be a benchmark for standardised PRO assessment, validation and interpretation.
