Why GP Evidence?

GP Evidence was developed to make the scientific evidence underpinning guideline-recommended treatments easier to access and understand for practising GPs.


Evidence-based guidelines are a highly valuable and critical element of our clinical practice. But they can promote “one-size-fits-all” practice, even though that was never their intention.

To make treatment decisions with an individual, while considering the pros and cons of a guideline-recommended treatment, some understanding of the evidence base for that treatment is essential.

We hope to bring to the surface this important information and present it in a way that will be understandable, usable and useful.

Just for GPs? What about other healthcare professionals?


Much of the management of long-term conditions in primary care is undertaken by specialist nurses, primary care pharmacists and other healthcare professionals. We hope the content of this website will be useful and understandable to all these groups.

However, due to a need to focus on a particular user-group during development, it was designed with and oriented to the knowledge level of GPs – the language used and assumptions made (like use of abbreviations and jargon) reflect that. One day we may get to develop a truly multi-disciplinary version!

Where does the evidence come from?


The evidence presented here aims to be compatible with current NICE guidance.

Our principal data sources are NICE guideline evidence reviews and Cochrane reviews. Where other systematic reviews or individual studies have been cited, this is made clear, with an explanation of how these results sit alongside the most recent guideline recommendations.

There is a stepwise approach to evidence sourcing, collation and writing:

1) Examine NICE guideline evidence reviews to see if they provide usable data to present. If not, then refer to

2) Cochrane reviews. Often we have looked at NICE and Cochrane reviews side by side to see which provides the most appropriate and highest quality data. If information is still not available, we conduct

3) Pragmatic (rather than systematic) searches for other systematic reviews or occasionally single studies from the medical literature

  • Care is taken in this situation to consider if these evidence sources are broadly compatible with NICE guidelines, represent high quality unbiased research, and have entered mainstream discourse.
  • Where there are uncertainties or controversies, this is highlighted.

4) Seek expert advice from subject experts (usually primary care academics) to find up-to-date reviews or studies and understand current thinking in a field.

An Expert and Patient Steering Committee, comprised of three experts in evidence synthesis/interpretation and three expert patients, were involved in this process in two ways:

  • Co-production of the strategy/approach to evidence collation and curation.
  • Reviewing and advising on dilemmas and choices in evidence selection, interpretation and presentation.

The bulk of the work of evidence collation, curation and presentation was undertaken by the project lead (JT, see below).

A systematic, second-reviewer data extraction check was undertaken on all quantitative data by a team of academic peers (see acknowledgements).

How is the evidence kept up to date?


We aim to keep evidence up to date with latest NICE guidance, and use NICE guideline updates as a trigger for updating our content. Dates of all research presented are included in the text or references on this site.

NICE guidelines have historically only been updated every 2-4 years, and so can get out-of-date themselves. However, at time of writing (February 2023), NICE is implementing a new way of working which will involve more frequent, rapid updates to their guidelines.

If a major piece of research is published which should be practice changing, we may consider updating our content to include this, but generally prefer evidence to have gone through an independent, high quality systematic review process.



GP Evidence is free for users to access and carries no advertising.

Development was funded by the National Institute for Health Research (NIHR) [Doctoral Research Fellowship DRF-2018-11-ST2-021].

The views expressed on this website are those of the author(s) and not necessarily those of the NIHR, NHS or the UK Department of Health and Social Care.

GP Evidence is independent of pharmaceutical industry, and any other bodies who might seek to influence prescribing on any basis other than best evidence.

Who developed GP Evidence?


This project was conceived and undertaken by Dr Julian Treadwell, a GP, who after many years of practice (including enthusiastic use of clinical guidelines), became frustrated at the difficulty of providing person-centred care in an increasingly regulated environment.

The simple idea that a more transparent presentation of evidence would help GPs and patients work with guidelines (rather perhaps than for them), led to a mid-career diversion into academic practice. Following an MSc in Evidence-based Health Care, he developed GP Evidence as a DPhil (PhD) project at the Nuffield Department of Primary Care Health Sciences, University of Oxford. His clinical practice is as a GP in Oxford.

The DPhil thesis describing the development of GP Evidence is available online.

Academic supervisory team:

Professor Trish Greenhalgh

Professor Kamal R Mahtani

Professor Gina Neff

Dr Joanna Crocker

Dr Sietse Wieringa

The design of GP Evidence


Making complex information understandable and usable is a huge challenge. To find out how to do this, we used a participatory co-design approach: where the intended users of a product are involved in its creation from the very beginning, in contrast to a “top-down” design approach.

In due course, we will publish a full description of this process and link to it here. For now, the key steps in the project were:

Patient and Public Involvement from the outset of the project, to ensure that what we thought were GPs’ needs aligned with patients’ priorities. Continued involvement through the Steering Committee.

Stakeholder consultation in the fields of clinical guidelines, shared decision making, evidence-based practice, key medical institutions.

In-depth interviews with practising GPs.

Prototype development with professional web designers (Nexer Digital).

Accessible design principles employed.

Prototype redesign with GPs, where the website design was re-done from rough prototype “live” with a group of GPs and a web designer and user-experience expert.

Multiple cycles of user testing and small scale redesign with GP users, including focus groups.

“Content design” principles applied to textual content, with all text undergoing “pair writing” editorial  with (a) a professional editor and (b) a GP user.

Preliminary evaluation focus groups with “fresh” GP users. These demonstrated the ability of the website to deliver understandable, potentially practice-changing information.

We hope this process has produced a genuinely useful “thing” in a world of information overload. The insights gained from this level of user involvement were incredibly valuable and significantly shaped the finished product.



Heartfelt and sincere thanks to all those people who were so generous with their time in contributing to this project.

Expert Patient steering committee: Jon Brassey, Andy Hutchinson, Emily Lam, Kamal Mahtani, Mandy Payne, Jackie Walumbe.

Fellow doctoral researchers who assisted with data extraction and user testing: Laura Armitage, Rebekah Burrow, Kiana Collins, Laura Heath, Olu Onyimadu, Amelia Talbot, Aziza Wahedi.

Professional editorial: Mandy Payne.

Web design: Nexer Digital. Special thanks to Elizabeth Buie, Ben Holden, Hilary Stephenson.

JT would like to offer personal thanks to the huge numbers of people over the last several years who have contributed in small ways to this project with encouragement, advice and constructive challenge. GP Evidence would not have happened without you.


Declarations of Interest


The project lead, academic supervisors and steering committee have been asked to declare any conflicts of interest according to the International Committee of Medical Journal Editors guidelines 2021.

JT received a salary for the duration of this project funded by the NIHR Fellowship Award listed under the funding section above. He has a small role with NICE as a moderator of their GP Reference panel. He is an associate editor of the Drug and Therapeutics Bulletin. JB is a major shareholder in the Trip Database search engine as well as being an employee. In relation to this work Trip has worked with a large number of organisations over the years. The main current projects are with the Centre for Evidence-Based Medicine (Oxford), AXA and Wolters Kluwer. TG is a member of Independent SAGE and an unpaid adviser to the philanthropic fund BALVI. AH is a Senior Medicines Adviser at NICE. He is closely involved in NICE’s work on shared decision making, including the NICE guideline on SDM, and leads on the development of NICE’s patient decision aids. MP is a freelance medical editor, and edits the newsletter for the UK charity HealthSense which promotes evidence in healthcare. She has previously provided freelance bioethics and publication ethics consultancy and training to GSK. She received payment for freelance editing support in the development of this website. SW is a paid member of an advisory committee for Up to Date and the Dutch GPs’ Society NHG.  JC, EL, KM, GN, JW declare no conflicts of interest.



GPs’ understanding of the benefits and harms of treatments for long-term conditions: an online survey. Julian Stephen Treadwell, Geoff Wong, Coral Milburn-Curtis, Benjamin Feakins, Trisha Greenhalgh.

GPs’ use and understanding of the benefits and harms of treatments for long-term conditions: a qualitative interview study. Julian Treadwell, Joanna Crocker, Alexander Rushforth, Kamal Mahtani, Trish Greenhalgh.

Treadwell, J. S. (2023). Improving GPs’ knowledge of the benefits and harms of treatment to support decision making in multimorbidity: qualitative research and co-design of a novel electronic information resource [PhD thesis]. University of Oxford.