For most of the history of medical research, patients and the public were the subjects of study — the people research was done to, or at best for. The questions researchers asked, the outcomes they measured and the way they ran their studies were decided by professionals, often without consulting the people whose lives the research was meant to improve. The result was sometimes research that answered questions patients did not find important, measured outcomes that did not matter to them, or imposed burdens that could have been avoided had anyone asked. Patient and public involvement — PPI, often extended to PPIE for involvement and engagement — represents a deliberate change in that relationship: research done with patients and the public, not merely on or for them. It belongs within the engagement, impact and SDG domain of the CASRAI Dictionary.
What PPI is — and is not
A precise distinction matters here, because the terms are easily confused. Involvement means research carried out with or by members of the public, rather than to, about or for them — people with relevant lived experience actively shaping the research. This is different from participation, which is taking part in a study as a subject (for instance, being a participant in a trial), and different from engagement, which is about sharing information and findings with the public. PPI specifically concerns the active contribution of patients and the public to how research is done: helping decide what questions to ask, advising on whether a study is feasible and acceptable, commenting on the burden it places on participants, shaping how findings are communicated, and contributing to governance and oversight. The premise is straightforward but powerful: people with lived experience of a condition bring knowledge that researchers, however expert, simply do not have, and that knowledge makes research better.
Why involvement improves research
The case for PPI is not merely ethical, though it is that; it is also practical. Involving patients and the public tends to make research more relevant, because it is more likely to address questions and outcomes that matter to the people affected. It makes studies more feasible and acceptable, because those with lived experience can foresee practical problems — an unreasonable testing schedule, confusing materials, an outcome measure that misses the point — that professionals might not anticipate. It can improve recruitment and retention, because research designed with participants in mind is easier to take part in. And it strengthens communication, because involving the public helps ensure findings are shared in ways people can actually use. PPI is not a courtesy added at the end; done well, it changes the research for the better from the start.
Frameworks that guide good PPI
Because involvement can be done superficially — a single token consultation used to tick a box — the field has developed frameworks to guide genuine practice. In the UK, the National Institute for Health and Care Research (NIHR), building on the long-running work of the body once known as INVOLVE, has been central to embedding PPI in health research. The UK Standards for Public Involvement set out what good involvement looks like across several areas — including inclusive opportunities, working together, support and learning, communications, impact, and governance — giving organisations and researchers a benchmark to plan against and improve towards. The aspiration these standards express is co-production: an approach in which researchers, practitioners and the public work together as equal partners, sharing power and decision-making throughout, rather than the public being consulted at the edges. Co-production is demanding and not always the right model for every study, but it marks the deep end of meaningful involvement towards which the standards point.
Reporting PPI: the GRIPP2 checklist
A persistent weakness in the field has been that involvement, even when it happened, was often reported vaguely or not at all — a paper might mention “patients were involved” without saying who, how, or to what effect, leaving readers unable to judge its quality or learn from it. The GRIPP2 checklist (Guidance for Reporting Involvement of Patients and the Public) was developed to address exactly this. It provides a structured set of items for reporting PPI in research papers, prompting authors to describe several things clearly:
- The aim of the involvement — why patients and the public were involved.
- The methods — how they were involved, and at which stages.
- The results — what difference the involvement made to the research.
- A critical reflection — what worked, what did not, and what was learned.
By standardising how involvement is reported, GRIPP2 makes PPI visible, assessable and cumulative. It allows readers to judge whether involvement was meaningful, and it lets the field learn collectively what good practice looks like instead of every team starting from scratch.
Involvement, contribution and impact
Taking PPI seriously raises a further question that the research community is still working through: how to recognise the contribution of patient and public partners. People who help shape a study contribute real intellectual work, and recognising that contribution — through acknowledgement, through appropriate authorship where warranted, and through fair compensation for their time — is part of doing involvement well rather than extractively. Frameworks for describing contribution, such as the broader thinking explored in our material on authorship and contribution, are increasingly relevant as the community considers how the input of public partners should appear in the record. PPI is also closely tied to research impact: studies shaped by those they aim to help are more likely to produce findings that are used and that make a difference, which is the ultimate concern of the engagement and impact domain.
A consistent vocabulary for involvement
For PPI to be planned, reported and recognised consistently across studies, funders and institutions, the terms involved — the stages of involvement, the roles public partners play, the standards being met — must mean the same thing everywhere. That consistency is what the CASRAI Dictionary works towards: a shared vocabulary so that involvement is described and understood the same way wherever it is recorded. And because public partners’ input is genuine contribution, it can be acknowledged within the same framework used for every other — the CRediT taxonomy and its full set of contribution roles. Health research is increasingly something done with the public rather than merely upon them; frameworks like the UK Standards and GRIPP2 are what turn that principle into reliable, reportable practice.