When interviewed, the researcher spoke of her personal expectations that PPI would help kinase assay to maximise recruitment, ensure the right outcomes were measured, and help in interpreting the findings. There was no PPI contributor interview but the researcher also

spoke of having to tailor ‘different ways of involving people’ in PPI depending on the ‘population of interest’: It might be children, people from disadvantaged groups or older people [...] so you probably have to find other tailored ways of including people to make it effective. So it’s not a one size fits all. (CI 7) The majority of those researchers interviewed who described such ‘as and when’ contributions (10/12) spoke of expectations for PPI, and tended to view responsive modes as constructive. Only in one case (trial 101) did the researcher allude to the PPI within their trial as a ‘tick box’ exercise. Three trials undertook additional responsive PPI activity that had not been specified in their documented plans. Trials 21 and 102 expanded on their plans by involving PPI contributors

in a broader range of activities than initially indicated, namely advising on recruitment and interpretation and dissemination of study findings. As with trial 21 (described in the Managerial Mode section above), we could not determine from the CI interview why plans for Trial 102 had been expanded, and there was no PPI contributor interview for trial 102 to help illuminate this issue. The PPI contributor for the third trial (trial 91) mentioned that she sought the views of ‘women’s groups’. This was additional to the documented plans for her to be involved in ‘protocol design of the study’. As with Trial 21, this PPI contributor had previous PPI experience

and appeared to be a particularly active member of the research team, and with considerable knowledge of the relevant health condition. In summary, most applicants implemented their documented plans for PPI regardless of the mode of planned involvement. In five cases we were unable to discern whether or not PPI plans were fully implemented, although some PPI was achieved in these trials. Regardless of whether PPI was implemented as planned GSK-3 or evolved, most trial teams faced challenges and learnt lessons about implementing PPI as they went along. We now turn to their accounts of this learning and then use these to derive practical advice for planning and implementing PPI. Researchers on the challenges of PPI and lessons learnt Most CIs spoke of the challenges they encountered in implementing PPI (table 2) and things they would do differently as a result. The involvement of trial investigators’ own patients as contributors was perceived to lead to a ‘conflict’ (CI 20) between an investigator’s research and clinical roles.