The Oxford Vascular Study (OxVasc) began in 2002 and involves University of Oxford staff at the John Radcliffe Hospital providing clinical care, carrying out scans and other investigations, and collecting detailed research data and blood samples. Professor Peter Rothwell, Head of the Wolfson Centre for the Prevention of Stroke and Dementia at the Nuffield Department of Clinical Neurosciences, founded and directs the study.
We want to thank all of the patients and their relatives in Oxfordshire who have helped us so much, as well as the local general practices who help make the study possible. The study is a good example of how relatively simple clinical research can still provide insights that substantially improve patient care as well as allowing us to study the causes of disease. - Professor Peter Rothwell
Over the last 20 years the study has recruited nearly 13,000 Oxfordshire participants and has then followed their progress for at least 10 years. It is the first study in the world to assess and follow up all vascular conditions at the same time in the same population. It is a collaboration with about 100 GPs covering a population of nearly 100,000 residents of Oxfordshire.
OxVasc has provided vital data on the frequency, time-trends, causes, outcomes and treatment of strokes, transient ischaemic attacks (TIAs, or mini-strokes), heart attacks and other circulatory problems, as well as subsequent complications, such as dementia.
More than 100 researchers have worked on the study to date, publishing nearly 400 scientific papers, some leading to major changes in clinical practice locally, nationally and internationally. These include:
- Demonstration of the very high risk of major stroke after minor 'warning' symptoms, which led to the development and widespread implementation of emergency stroke prevention clinics.
- Showing that urgent treatment of patients following these events reduces the risk of major stroke by 80 per cent - one of the most effective interventions across all of medicine.
- Identification of fluctuating blood pressure as a powerful risk factor for heart attacks and strokes.
- Use of mobile phone telemetric home blood pressure monitoring to properly diagnose high blood pressure and to monitor treatment.
- Showing the benefits of more detailed investigation into the causes of stroke in elderly patients.
- Discovery of several transient neurological symptoms that commonly precede major strokes, but that were previously thought by doctors to be benign and not to require treatment.
- Better understanding of the risks and risk factors for the development of dementia after heart attacks and strokes.
- Identification of a worrying rise over the last decade in the number of unexplained strokes occurring in young adults and determination of potential causes.
Patients are enrolled while in hospital or following referral by participating GPs to a daily emergency outpatient clinic at the John Radcliffe Hospital. Detailed clinical assessments are made and participants undergo state-of-the art investigations, including brain imaging, and then home monitoring of blood pressure and heart rhythms. Relatives and friends can also consent to participate so that comparisons can be made between people who have had a vascular event and those that have not.
Antonia, a 67-year-old teacher from South Oxfordshire, had a TIA in November 2021 and was seen by the OxVasc team the next day, having been referred by her GP. She enrolled on the study when it was confirmed she had had a TIA. At the time, she had no idea that was what had happened to her; generally very healthy, with low blood pressure, she felt disorientated at work and then experienced loss of vision: 'It was grey and fuzzy - quite surreal. The actual TIA lasted around two or three minutes – but it seemed longer.'
Antonia continues: 'It was only when I got home and started explaining it to my daughter – she looked horrified and said I should see a doctor.' Her GP contacted the Oxford Vascular team, who got in touch with Antonia within half an hour, asked to see her right away, and found a small acute stroke on her MRI brain scan. 'It's hard to take it all in when you don't have the health risk factors. It never occurred to me that something related to strokes could happen to me. When they asked me if I'd like to take part in the study, I was very happy to. I am curious about other possible causes, as I don't have the usual risk factors. It has helped me so much – they do so many tests and they explain everything to you. It has helped me to understand what happened, but also be active in preventing it. Research like this is important in raising awareness among people so they can be more active in preventing themselves or their family having a stroke,' Antonia explains.
Another participant, Yvonne Hewett of Wantage, aged 79, had a TIA in January 2019, while shopping with her daughter. When she reached for her purse to pay, she was unable to grasp anything with her left hand. Although she did not collapse, she had felt unwell that morning. 'My daughter recognised what was happening and took me straight to the JR Hospital,' Yvonne says. 'I was seen very quickly, had numerous tests, was given tablets immediately and having seen the Emergency Department doctor and stroke doctor, was discharged the same afternoon.' She was asked if she wanted to participate in the OxVasc study by her GP. Yvonne attended four OxVasc follow-up appointments during the 12 months following the TIA, during which a series of tests were carried out. Now her next follow-up is in five years' time.
Like Antonia, Yvonne regularly checks and records her blood pressure at home and submits the readings to the trials team. In the meantime, she has been advised to lose weight and to stay as active as possible. 'It's important to take part in trials like this to improve understanding of conditions and each person's specific experiences. This can lead to developments in treatments and broaden understanding of conditions, including the effects medications are having on individuals,' Yvonne says. 'Overall, I am very glad that I have been part of this study as I have felt and continue to feel very well supported following this incident. In the first 12 months after the TIA, the support I was able to access enabled my confidence to return and my fear to dissipate. I would be happy to take part in any other relevant clinical trial or study.'
One of OxVasc's key strengths is that participation is extremely high, with more than 99 per cent of patients who are asked to take part in the study giving their consent to at least some collection of data, thus avoiding 'selection bias', where the sample may not represent the whole population. This completeness of coverage allows researchers to draw conclusions from the data that are as reliable as possible on a host of different topics ranging from studies of genetic factors and other 'biomarkers' for risk of disease to studies of how best to deliver high-quality clinical care.
OxVasc is co-ordinated by the University's Wolfson Centre for the Prevention of Stroke and Dementia in partnership with Oxford University Hospitals NHS (OUH) Foundation Trust, which runs the John Radcliffe Hospital.
The study is aiming to continue to recruit until 2027 and to follow participants up until 2032. It is funded by the Wellcome Trust, The Stroke Association, British Heart Foundation, Masonic Charitable Foundation, and the NIHR Oxford Biomedical Research Centre, a partnership between Oxford University Hospitals NHS Foundation Trust and the University of Oxford. Previous funders have included the Medical Research Council, European Union, and the Dunhill Medical Trust.