In this blog, we explain why OpenSAFELY works this way, what it means in practice, and some useful tips for working with event-based information using patient-level datasets.
Samina Begum and Godwin Daudu, two members of our OpenSAFELY Digital Critical Friends group, reflect on their experiences at the 2026 PEDRI Forum.
We’re looking for an experienced product manager to join our team at the Bennett Institute for Applied Data Science, University of Oxford, working on OpenSAFELY and our other products.
Lessons from a recent PPIE event that are shaping our research into learning disability and epilepsy.
How, and why, we brought together a diverse group of people with lived experience of using the NHS Talking Therapies’ service to support the OpenSAFELY NHS Talking Therapies project.
What we learned about how researchers use and reuse codelists across OpenSAFELY studies.
What we learned about how researchers create and reuse variables across OpenSAFELY studies.
How we combined different editions of ICD-10 so that one codelist works across multiple OpenSAFELY datasets.
Key challenges in identifying pregnancy codes in EHRs and solutions to help researchers make sense of incomplete or conflicting health records.
An explanation of how a simple pregnancy algorithm was built and checked in EHRs, with a focus on anomalies and limitations.
Researchers use OpenSAFELY to analyse the Pharmacy First’s service uptake, data quality, and integration into primary care systems.
A new study using OpenSAFELY has found that diagnosis rates for several autoimmune rheumatic diseases remain below expected levels five years after the start of the COVID-19 pandemic.
Dr. Jamie Cummins reflects on a six-month research stay at the Bennett Institute, where he developed and evaluated AI-assisted tools to improve research transparency, reproducibility, and trustworthiness.
For International Women in Engineering Day, Nishtha Kalra reflects on confidence, curiosity, and why representation matters in inspiring the next generation of female engineers.
Seb Bacon, newly appointed Professor of Research Software Engineering at the Nuffield Department of Primary Care Health Sciences, gives his inaugural lecture on health data, privacy, and public accountability.
Study using OpenSAFELY finds that pre-vaccine shielding prevented thousands of COVID hospitalisations across England
The impact of media narratives and large-scale health data tools on migrant health
OpenSAFELY was built for healthcare. When the National Institute of Teaching approached us about applying the same approach to school data, we were enthusiastic. Here is what we found when we got into the detail.
Covid-19 inquiry finds OpenSAFELY’s data infrastructure essential to UK’s pandemic response.
Understanding the role that large-scale mental health data analysis can play in improving the effectiveness of mental health services across England.
We describe how we do data checks of GP data in OpenSAFELY
Seb Bacon and Brian MacKenna showed returning graduates how healthcare data tools are developed, and explored the impact of securely analysing large-scale health data.
We are delighted to announce that - from today - you can submit applications to the OpenSAFELY service for non-COVID-19 studies.
Our recent paper showing the impact of the pandemic on opioid prescribing in people waiting for treatment
We describe how we used the Waiting List Minimum Data Set within OpenSAFELY
We’ve made a video!
We’re excited to open registration and submissions of ideas for the 2025 Bennett Institute Medicines Symposium, a two-day event that brings together everyone working with NHS medicines data.
We are looking for people to be part of a new Experience-led Public Advisory Group that will meet regularly to advise and guide the development phases of the OpenSAFELY-Talking Therapies programme.
Applications closed. Epidemiologist / Health Data Scientist roles delivering OpenSAFELY research, reproducible analysis tools and support for researchers.
Applications closed. Patient and Public Involvement and Engagement Manager role bringing lived experience of mental health services into OpenSAFELY-Talking Therapies.
This blog post shares the project I worked on during my summer internship at the Bennett Institute as part of the HDR UK Health Data Science programme. My project explored how ehrQL, is being used across OpenSAFELY repositories. I analysed 301 codefiles from 65 Repositories under the OpenSafely org. and was able to identified which features researchers rely on most, which are less common, and where improvements or additional support could be valuable.
The journey of public involvement in OpenSAFELY. The OpenSAFELY Digital Critical Friend group, from conception to becoming foundational for OpenSAFELY, is a testament to the power of effective public involvement in digital health.
On the 24th June 2025, OpenSAFELY had the privilege of running a booth at the National Patient Data Day in Leeds!
Office hours, coding meetups and more! Come and talk to other OpenSAFELY users.
Together with collaborators in Bristol and at the Bennett Institute, we created a reusable action called ‘diabetes-algo’. Here is what it does.
Our tech team has been making improvements to OpenCodelists! What’s new?
In January 2025, Eli (our Research Software Advocate) sat down for an interview chat with Hannes Lowette and discussed all things OpenSAFELY.
Applications closed. Two senior software developer roles building and operating OpenSAFELY, with a focus on web development and infrastructure.
Applications closed. Product Manager role shaping OpenSAFELY and other Bennett Institute products with researchers and software engineers.
A new version of the OpenSAFELY R image with R 4.4.3 and updated libraries is available
Ben Goldacre on our short term future plans, as published in our booklet, “The past, present and future of OpenSAFELY”
Ben Goldacre reflects on OpenSAFELY’s funding journey to date, as published in our booklet, “The past, present and future of OpenSAFELY”
Ben Goldacre describes the collaboration that makes OpenSAFELY possible, as published in our booklet, “The past, present and future of OpenSAFELY”
A short OpenSAFELY case study from the University of Southampton, as published in our booklet, “The past, present and future of OpenSAFELY”
A short OpenSAFELY case study from the University of Manchester, as published in our booklet, “The past, present and future of OpenSAFELY”
A short OpenSAFELY case study, from the UK Health Security Agency, as published in our booklet, “The past, present and future of OpenSAFELY”
Ben briefly celebrates our paper setting out proposals for the shape and scope of the government’s new National Data Library.
In light of recent press coverage, Bennett boss Ben Goldacre explains what OpenSAFELY is, how it works, and why it matters - in just a few bullet points.
This morning the Today programme on Radio 4 did two great spots on OpenSAFELY.
A short OpenSAFELY case study from the team at the London School of Hygiene and Tropical Medicine, as published in our booklet, “The past, present and future of OpenSAFELY”
We’ve made a video!
We want to understand what matters most in terms of the experience for people going through pregnancy and maternity care. We want to answer research questions that are important to women, so we’re very keen to find people with lived experience who want to be part of a Public Advisory Group to support this work
A short OpenSAFELY case study from King’s College London, as published in our booklet, “The past, present and future of OpenSAFELY”
A short OpenSAFELY case study from the University of Bristol, as published in our booklet, “The past, present and future of OpenSAFELY”
A short history of OpenSAFELY’s beginnings, as published in our booklet, “The past, present and future of OpenSAFELY”
Our workflows emoji dashboard makes sure that our tech team are aware of any testing or deployment failures.
How we engage with patients and the public, as published in our booklet, “The past, present and future of OpenSAFELY”
A brief review of information governance, as published in our booklet, “The past, present and future of OpenSAFELY”
A brief look at our output checking service how it works, and why it’s necessary. As published in our booklet, “The past, present and future of OpenSAFELY”
A brief look at how we enable federated analytics, as published in our booklet, “The past, present and future of OpenSAFELY”
A brief overview of our co-piloting programme, as published in our booklet, “The past, present and future of OpenSAFELY”
We’ve greatly improved autocomplete when writing ehrQL. But how on earth do you test it automatically?
A brief overview of OpenSAFELY, as published in our booklet, “The past, present and future of OpenSAFELY”
We produced a little printed book, “The past, present and future of OpenSAFELY”. This post is the first in a series, in which we’ll re-produce the book on the web.
Our new tool for viewing and releasing outputs
Bennett research integrity lead, Nick DeVito, on the encouraging words about code sharing that Kamran Abbasi delivered at our recent OpenSAFELY Community Symposium.
We’re launching a new project to explore migrants’ health using OpenSAFELY and we’d love to hear from you.
A full list of links to all the videos from day one of our 2024 OpenSAFELY Community Symposium
Last week we hosted the OpenSAFELY Community Symposium in London - and it was a fantastic success.
We’re starting a new project to prepare maternity data for use in OpenSAFELY, and we’re keen to find collaborators to work with.
How a team used OpenSAFELY to investigate how the COVID-19 pandemic impacted patterns of weight gain
Could you help us to improve the research that we are doing into COVID-19 vaccination?
We’ve launched a new project to understand who received which COVID-19 booster shots, and when, and the impacts of this on health outcomes.
It’s not too late to register for our OpenSAFELY Symposium, which is happening in London on 25/26 November.
We briefly summarise all the recent big and exciting developments in hospital medicines data.
Someone on the radio was musing about using retail data for health - we have some thoughts on that.
In the past 6 months we’ve been very productive at OpenSAFELY publishing 21 peer-reviewed papers on a variety of topics.
In this guest blog, Katie Bechman describes the proof-of-principle pharmacovigilance study she conducted with the help of her team from King’s College London, which used OpenSAFELY to examine the safety of sotrovimab, paxlovid and molnupiravir in prehospital treatment of Covid-19.
Two days of talks and workshops on research, data infrastructure, and open science.
The Research Experience team explain how they’ve been recording decisions
Most of the time, we like to keep things fairly formal on this blog - but if you’ll forgive us a small indulgence, today we’re going to blow our own trumpet a little.
A couple of weeks ago, my colleague Rose Higgins and I went to an event in London where this Institute was awarded the Open Science Impact award, as part of the MRC Impact Prize.
We were, needless to say, over the moon about it. The whole team celebrated on Slack with a long list of appropriate emojis.
Spend more time answering your research questions – and less time wrangling your computer – with GitHub Codespaces and the OpenSAFELY development container.
Our new study looks at the rate that sick notes were issued for people with COVID-19, and how it changed over the course of the pandemic.
During the COVID-19 pandemic, there were no sustained increases in opioid prescribing.
We describe the features of OpenSAFELY that encourage and support reproducible research.
We describe some of our recent work investigating the impact of the COVID-19 pandemic on DMARD safety monitoring across >24 million patients’ records in England.
Applications closed. Research Software Advocate role connecting the OpenSAFELY engineering team with researchers through coding, tutorials and community events.
Debating STAR-PUs, launching Improvement Radar to identify prescribing improvements, and research on medication reviews during COVID-19.
Applications closed. OpenSAFELY engineering vacancies for junior, senior and staff developers, a tech lead and a product manager.
In the second of a two-part blog series, pharmacists Chris Wood and Vicky Speed talk about the results of their research on medication review activity
In the first of a two-part blog series, pharmacists Chris Wood and Vicky Speed talk about designing their research on medication review activity
Applications closed. Patient and Public Involvement Engagement Lead and Epidemiologist / Health Data Scientist roles supporting OpenSAFELY research.
How we organize and plan work for our tech teams
Ben discusses the OpenSAFELY platform with fellow nerd Tim Harford
Why prescribing analyses differ between platforms, a BNF-to-dm+d map, and updates to antibiotic and glucose test strip measures.
Here we describe some of our recent work investigating the impact of the COVID-19 pandemic on safe prescribing using a set of quality assured indicators across 57 million patients’ records in England
In this guest blog, Mark Green describes their latest paper using OpenSAFELY.
How can you be confident that the queries you write will be correctly interpreted and return the expected results?
To accompany the recent Ethnicity Short Data Report preprint we have created a short explainer for researchers using ethnicity in OpenSAFELY-TPP
The final session was a series of talks highlighting some of the research conducted in OpenSAFELY, some external perspectives on OpenSAFELY, and concluding remarks from our benefactor Peter Bennett, and director Ben Goldacre.
The third session in the Bennett Conference was a series of talks describing the overall operation of the OpenSAFELY platform and service.
A whistlestop tour of the whole history of our group, from OpenPrescribing via TrialsTracker to OpenSAFELY and on through Open Science, policy work, and more
The COVID-19 pandemic has reshaped many aspects of healthcare, including how antibiotics are prescribed in primary care settings. In this guest blog, Professor Diane Ashiru-Oredope lead pharmacist for antimicrobial resistance at UK Health Security Agency and our own Brian MacKenna, share some insights on repeat antibiotic prescribing and the link to health inequalities from a recent UK Health Security Agency analysis using OpenSAFELY.
We are delighted to share the announcement from NHS England and Department of Health and Social Care below, setting out the future of OpenSAFELY.
In this guest blog, Bang Zheng and Laurie Tomlinson from the London School of Hygiene and Tropical Medicine describe some of their lastest work on the comparative effectiveness and safety of currently recommended COVID-19 therapeutics in the community settings.
NHS medicines optimisation tools, an investigation into rising colesevelam costs, and a look at the pharmacists behind OpenPrescribing.
In this guest blog, Mark Russell describes the research that he has undertaken with the help of his team from King’s College London using OpenSAFELY.
Xiaomin Zhong, Ya-Ting Yang, Dr Ali Fahmi, Dr Victoria Palin and Professor Tjeerd Van Staa from Manchester University have been using OpenSAFELY for analyses focused on the impact of COVID-19 on antimicrobial resistance since 2021. In this guest blog they describe some of their recent papers that have been published in peer review journals.
In this blog post Millie Green shares some of the findings from a federated analysis carried out using OpenSAFELY.
In this blog we explain what codelists are, how they are constructed and review existing literature on construction processes.
Why did we create a new query language?
The OpenSAFELY Collaborative has won a prestigious CogX Award for the Best Innovation in Open Source Technology
In this blog, we describe the development of a set of key measures used to monitor the ongoing impact of the COVID-19 pandemic on primary care as part of the OpenSAFELY Service Restoration Observatory (SRO). The results from this work have now been published in eLife.
Here we introduce the Bennett Institute’s Information Governance team, explaining who they are, and what they do.
Our new paper describes some of the biases that exist when estimating COVID-19 vaccine effectiveness using routinely-collected health data, and discusses the use of target trial emulation to avoid or mitigate these biases.
An introduction to what clinical codes are, why they are used and the terminology systems used within OpenSAFELY work.
A summary of our findings from running the OpenSAFELY output checking service.
Millie and Laurie share how some of the outputs from the work on COVID-19 therapeutics have been used to inform policy and guidelines in the NHS and beyond.
The latest paper from our NHS Service Restoration Observatory, examining changes in primary care activity over the pandemic was recently published in the British Journal of General Practice.
Introducing the Bennett Institute’s Product team, where we talk about who we are, what we do and how we work.
Our OpenSAFELY study describing patterns in COVID-19-related mortality in the first five pandemic waves is now published open-access in the Lancet Public Health.
An outline the OpenSAFELY output checking service: who it involves, how our output checkers are trained and an overview of the output checking workflow.
Introducing the Bennett Institute’s Pipeline team, where we talk about who we are, what we do and some of the products we’re responsible for.
Here we introduce the Bennett Institute’s NHS Service Analytics team, explaining who they are, what they do, and why it is important.
Here we introduce the Bennett Institute’s Epidemiology team, explaining who they are, what they do, and why it is important.
Our OpenSAFELY study comparing the Pfizer and Moderna vaccines for protecting against covid-19 during the first booster programme in England is now published open-access in the BMJ.
Here we introduce the Bennett Institute’s Clinical Informatics team, explaining what they do and how their experience in NHS clinical practice helps them do this.
Hello, from the Bennett Institute’s Data Team! In this short blog post, we’ll describe our mission, our backgrounds in industry and academia, and what we’re working on now.
Taking some time to describe the co-piloting programme in numbers, to give an idea of the scale of this programme, who our co-pilots are and who we are working with
Better and more efficient health science with reusable pipelines and cross-disciplinary expertise.
Taking a deeper look at the ‘Safe Outputs’ dimension of this framework, and how it is applied in OpenSAFELY.
Here we outline some of the research that has been produced with OpenSAFELY, as well as the features that make it such a great platform for research.
The Fives Safes framework is a popular framework for designing safe and efficient data access systems that has been adopted by a range of Trusted Research Environments (TREs) across the UK.
On 7th May 2020, the OpenSAFELY Collaborative pre-printed the world’s largest study into factors associated with death from COVID-19, based on an analysis running across the full pseudonymised health records of 40% of the English population.
In order to tackle health inequalities NHS England have recently launched the Core20PLUS5 initiative to help local areas identify and reduce inequalities across key areas.
We recently presented on behalf of our team (grp-EHR) at an open science workshop, hosted by the MRC Biostatistics Unit at the University of Cambridge. This was a great opportunity for us to reflect on our team’s experiences using OpenSAFELY, and more broadly embracing open and team science approaches to our work.
As a team of co-pilots, we regularly take time to discuss how co-piloted projects are going and what we can do to help pilots and co-pilots make the most of their time together.
Rachel Seeley is the Head of Analytics at PrescQIPP CIC and has recently completed a project in OpenSAFELY on the safer use of anticoagulant medication. In this guest blog, Rachel describes her experience with using the OpenSAFELY platform and our co-pilot programme.
Bennett Institute resident pharmacist Brian MacKenna sets out some brief information on how we currently build medicines codelists on OpenSAFELY.
The launch of the Bennett Institute, the Goldacre Review, live Outlier Detection Dashboards, and new measures for DOACs and inhaler carbon footprints.
CIPHA and OpenSAFELY are hosting an introduction event for researchers in the North West of England who would like to work with CIPHA data using OpenSAFELY.
Our policy lead, Jess Morley, discusses the challenges involved in closing the gap in representation and reward for women working in these fields, and what we in the Bennett Institute are trying to do to help lower some of the associated barriers.
Previewing the Outlier Prescribing tool, updating measures and maps, and research on antidepressant prescribing and anticoagulant safety.
Applications closed. Clinical Informatician role in the Open Analytics Unit, translating clinical knowledge into NHS data analysis and open tools.
Applications closed. Lead Product Manager role shaping OpenSAFELY’s product direction, user experience and roadmap for secure clinical research.
I joined Bennett Institute in August 2021 to work as a data scientist on OpenSAFELY. This blog post describes my experience getting up and running with the OpenSAFELY pipeline.
Applications closed. Engineering Team Lead role leading web development for OpenSAFELY, an open source platform for secure clinical research.
Applications closed. Full Stack Web Developer role using React and Python to build OpenSAFELY, an open source platform for secure clinical research.
This is a guest blog from the team at Cantabular, who have been exploring how their technology might fit into the OpenSAFELY ecosystem.
All new users of the OpenSAFELY platform get access to our supportive co-pilot programme, where each new OpenSAFELY user is assigned a member of the OpenSAFELY team as their co-pilot for the duration of their project.
This week sees the publication of an independent Citizens’ Jury commissioned for NHSx and the National Data Guardian which found that OpenSAFELY was by far the most strongly and consistently supported of all NHS COVID data projects examined.
On our first anniversary, from the Policy Lead in the Bennett Institute, this is the brief story of the positive side from all our lives: how OpenSAFELY came to life, and what we’ve achieved so far.
This is a draft discussion paper, the first of a series exploring “open team science” approaches to managing health data, and specifically how to create a collaborative computational data science ecosystem where the sharing and re-use of objects such as codelists and code is facilitated, encouraged, recognised, and rewarded. As a microcosm of this we have first explored “codelists”. There are currently no ‘answers’ or preferred solutions given. We will be holding an open discussion with the research community on 2nd March at 3pm - you can book to join us here.
Applications closed. Epidemiologist / Health Data Scientist role using OpenSAFELY to study the impact of COVID-19 on patients and health services.
Applications closed. Platform Lead role combining Python development, software architecture and engineering leadership for OpenSAFELY.
Applications closed. Two software developer roles building OpenSAFELY, with specialisms in Python development and frontend user interfaces.
New hospital medicines data, plans for OpenPrescribing Hospitals, research on clinical software design, and an oral morphine equivalence update.
This is the code for the OpenSAFELY cohort extractor tool which supports the authoring of OpenSAFELY-compliant research, by:
It is also the mechanism by which cohorts are extracted from live database backends within the OpenSAFELY framework.
This is the repository for the OpenSAFELY job runner. A job runner is a service that encapsulates: the task of checking out an OpenSAFELY study repo; executing actions defined in its project.yaml configuration file when requested via a jobs queue; and storing its results in a particular locations.
The documentation is aimed at developers looking for an overview of how the system works. It also has some parts relevant for end users, particularly the project.yaml documentation.
This is the code for the OpenSAFELY job server designed for mediating jobs that can be run in an OpenSAFELY secure environment. The Django app provides a simple REST API which provides a channel for communicating between low-security environments (which can request that jobs be run) and high-security environments (where jobs are run).
Working on behalf of NHS England we have now built a full, open source, highly secure analytics platform running across the full pseudonymised primary care records of 24 million people, rising soon to 55 million, 95% of the population of England. We have pursued a new model: for privacy, security, low cost, and near-real-time data access, we have built the analytics platform inside the EHR data centre of the major EHR providers, where the data already resides; in addition we have built software that uses tiered increasingly non-disclosive tables to prevent researchers ever needing direct access to the disclosive underlying data to run analyses; code is developed against simulated data using open platforms before moving to the live data environment. Everything has run smoothly. We are fully live inside TPP; we are signed off with full data access and end-stage tech development for the computational platform with EMIS.
New papers on hospital medicines data, NHS analytics and statin prescribing, alongside updated CCG dashboards and OpenSAFELY COVID-19 research.
New research on unsafe methotrexate prescribing, bespoke prescribing email alerts, and analysis of COVID-19’s impact on prescribing in March 2020.
Introducing OpenSAFELY, COVID-19’s early impact on prescribing, rising price concession costs, and bespoke PCN email alerts.
OpenPrescribing.net has been updated this week with the latest release of prescribing data covering March 2020. In-depth analysis will be needed over the coming months, but this release gives us the first glimpse into the impact that COVID-19 has had on prescribing. At the Bennett Institute we have been quite busy with the new secure analytics platform OpenSAFELY but the following blog is a rapid analysis of the March prescribing data which others may find helpful to focus their own investigations. As always, all our analytical code is openly available on our GitHub for inspection and reuse by anyone.
