How can we describe impact of adult patient participation in health-service development? A scoping review

•Patient participation in health-service development is not a common practice.•Impact of patient participation in health-service development is understudied.•The literature describes a broad variation of impacts from service development.•Participatory health-service development leads to more patient participation.•Our review can be of practical relevance to those conducting service development. Patient participation represents a worldwide policy, but its impact lacks research. This study investigates impact of patient participation in health-service development by providing a comprehensive overview of how the literature describes it. A scoping review with a broad search strategy was conducted. The literature was examined for study characteristics, purpose for, approaches to and impact of patient participation. The data were analyzed using a thematic analysis. The 34 included primary studies reported impacts of patient participation that were interpreted to constitute two categories: 1. The participatory process´ impact on involved patient representatives and health professionals, and the organization´s patient participation practice itself. 2. The participatory service development´s impact on the design and delivery of services regarding patients and health professionals, and the organization. The literature describes a broad variation of impacts from health-service development, relevant for health professionals and patient representatives when initiating or participating in such processes. Our review provides an overview and discussion of these types of impact. The findings can be of practical relevance to those aiming to develop services, quality indicators regarding effects of patient participation, or to further investigate aspects of participatory service development.