There is limited evidence regarding the outcomes and impacts of Patient and public involvement (PPI) in research, mainly based on narrative studies. Existing frameworks for supporting and evaluating PPI often require adaptation to specific contexts, and comprehensive instruments are needed. From an international perspective, strengthening the scientific foundation that underpins PPI is crucial to generate stronger evidence to understand which approaches work best, in which contexts, and with what effects.

To promote PPI implementation in German health research, this project aims to (1) Establish an evaluation framework, (2) Develop a modular evaluation tool in the form of a questionnaire and (3) Pilot and psychometrically validate the tool.

A three-phase mixed methods approach will be employed, integrating qualitative and quantitative data. First, we will explore with researchers, research partners and other stakeholders in health services research what contributes to meaningful and successful PPI through a web-based survey and focus groups. Findings are discussed in a codesign workshop in which participants agree on an evaluation framework based on a LOGIC model. Second, items from international instruments that evaluate PPI are deductively assigned to the evaluation framework. Further items are developed based on the focus groups from phase 1. Cognitive pretests and qualitative review will be conducted with researchers and patients in order to refine the item pool and develop the evaluation tool. Third, the evaluation tool with modules for researchers and patients will be piloted in a web-based survey. Data analysis will include thematic analysis for qualitative data and descriptive and psychometric analyses for quantitative data. A participatory research team will provide ongoing support throughout all project phases.

Ethical approval has been obtained from the Local Ethics Committee of the Centre for Psychosocial Medicine, University Medical Centre Hamburg-Eppendorf (LPEK-0889). The study will follow the principles of the Helsinki Declaration and good scientific practice. Results will be disseminated at national and international conferences, public symposiums and in peer-reviewed journals, contributing to the internationally developing field of PPI in research and addressing relevant research gaps.