Table 1. IMPRESS case studies and their organisation of PPI.

Case Study	Type of research	PPI model, PPI roles	PPI forums	Interview
1	Mixed methods: evaluation	Intertwined PPI with outreach 4 x PPI (1 x Advisory group; 1 x Advisory Group + Co-researcher; 1 x national patient rep; 1 x Hospital advocacy officer)	Advisory group+ Co-researcher	Res = 2 PPI = 2
2	Mixed-methods: service mapping and health economic costing	Intertwined PPI 8 x PPI recruited for previous linked study.	Advisory group	Res = 5 PPI = 5
3	Mixed methods: physiological monitoring and qualitative	One off PPI 9 x PPI recruited through a local patient day centre	PPI day- pilot work	Res = 1 PPI = 0
4	Mixed methods. Participatory Research	Intertwined PPI 9 x PPI Duel role (both research participants and co-researchers). Steering group includes 1 x parent/carer collaborators	Co-researchers Steering group	Res = 2 PPI = 0
5	Secondary data analysis	One-off PPI 2 x projects in theme consulted PPI panel	Telephone consultations and meetings with service users regarding patient pathways and design and timings of questionnaires	Res = 2 PPI = 0
6	Mixed methods: exploratory design and systematic review	Intertwined PPI with outreach PPI from previous study fed into research questions. Wide consultation by CI of local SU groups. 4 x PPI on current project + 1 x PPI co-researcher piloted the data extraction tool	PPI from 2 previous projects fed into CS06. Face-to-face consult with local SU charities/orgs etc.; Project steering group stakeholder group	Res = 2 PPI = 2
7	Systematic Review	One-off PPI group (of SU) set up for previous study consulted in development of this study 2x local PPI groups (general PPI)	Virtual, via e-mail/post with one PPI group. Face-to-face with another PPI group. Comment on protocol and suggest questions for literature review	Res = 4 PPI = 1
8	Mixed Methods: document analysis, observations and systematic review.	None		Res = 2 PPI = 1
9	Qualitative: Evaluation	One off The project has had difficulty with securing a clear direction and has struggled with defining and implementing PPI. (Carer Collaborator)	PPI contributors and other stakeholder reviewed project proposal; advised on the advertising of the project to service users and Collaborator) with the writing of a lay summary	Res = 2 PPI = 1
10	Mixed methods	Intertwined PPI group (generic)	Advisory group also advising on documents and processes.	Res = 2 PPI = 1

Abbreviations: Res = Researcher, PPI = Patient and Public Involvement contributor, SU = Service User, CI = Chief Investigator.