The three case studies presented clearly show substantial evidence of positive impact on the quality of research. The effect was on research processes, outcomes, the researchers themselves, patients and members of the lay public concerned.
The studies are a good illustration that every trial situation is unique and, therefore, PPI will be different in each situation. The study outcomes, local regulations, and study participants determine methods and evaluation of PPI that will be used. Qualitative methods are required, for example in surveys, to determine if there is an impact on outcomes, the research process, the patients, members of the public, participant observation in real time, and the researchers.
In the PLEASANT trial, successive consultations with parents/guardians and asthma-affected children/students significantly influenced the trial preparations, intervention timing, and eventual data interpretation. The research outcomes would, conceivably, be positively influenced.
Similarly, PPI in the trial on acute stroke increased the interest of patients and the public in such a way that they were free to advise on the study design and types of outcome measures. As a consequence, the researchers introduced new outcome measures through enhancing the standard assessment questionnaire; thus making the study results “more relevant to the patients”.
The AUKCAR scenario is perhaps the most impressive of the examples. The Centre applies PPI throughout, from research proposal and design to results dissemination.
The impact is, correspondingly, far more comprehensive. There are remarkable effects on individuals’ and families’ lives; subsequent approaches to patient management and follow up strategies, among others, are cited.
It is difficult to determine if there are gaps in the evidence, given that methods of research conduct and PPI impact assessment may vary considerably. The PPI impact on quantitative study methods, for instance, is not particularly highlighted in the case studies considered.