Almost a million people in the UK are living with dementia. The SAIL Databank provides a powerful resource opportunity for researchers to study the causes, prevention and treatment of dementia. Researchers from the University of Edinburgh worked with the SAIL team to develop the SAIL Dementia electronic Cohort (SAIL-DeC). We sat down with Dr Tim Wilkinson, Consultant Neurologist and Senior Clinical Research Fellow at the University of Edinburgh, to discuss the creation of SAIL-DeC and its applications.
What gave you the idea for SAIL-DeC?
During my PhD, I worked with mutliple routinely-collected health datasets from around the UK. I thought the SAIL Databank was by far the best resource due to its breadth and the straightforward nature of the data application process. My research is focused on dementia, so I was particularly attracted to SAIL as they had obtained primary care data – this was no mean feat! Fortunately, most people living with dementia are living in the community, so primary care data can provide us with important information on those people. I thought SAIL was such a fantastic resource, so I wondered why it wasn’t being used more for dementia research. I concluded that one barrier was the complexity of the data, particularly when using primary care data. Every time someone wanted to use SAIL to study dementia they would have to understand and manage billions of rows of data. I was working closely with Dr Christian Schnier, Senior Epidemiologist at the University of Edinburgh, who could manipulate and curate these very large datasets, but not everyone would have such ready access to this technical expertise. We thought there must be a way to improve this system, to reduce duplication of effort and to attract a wider range of dementia researchers to using SAIL. We were awarded funding from Dementias Platform UK to create a virtual research-ready dementia cohort from SAIL data.
How does SAIL-DeC work?
The idea behind SAIL-DeC is quite simple. The SAIL Databank contains linked routinely-collected data for the population of Wales. Rather than each researcher being faced with the ‘raw’ data (meaning they would have to start from scratch when defining risk factors and diseases of interest) we used code lists to define various diseases and risk factors. This produced a curated, ‘research-ready’ cohort. Researchers could use our disease definitions or they can create their own, so the resource can improve over time. Rather than being faced with billions of rows of raw data, researchers are given a simplified, curated cohort. We designed SAIL-DeC so that it could be used for a wide range of studies, such as investigating dementia risk factors, looking at prescribing trends in dementia and looking at the outcomes for people after receiving a dementia diagnosis.
How many people are there in SAIL-DeC?
When we first created SAIL-DeC, we only included people who were aged 60 and older by the end of follow-up, meaning there were 1.2 million people in total. Of these, 130,000 developed dementia at any point. The inclusion criteria have since been broadened, so SAIL-DeC now includes anonymised data on most of the adult population of Wales.
What has SAIL-DeC been used for so far?
Our first paper described the creation of SAIL-DeC. We then conducted a medication-wide association study, in which we looked at the associations between all prescribed medicines and the risk of dementia in half a million people in Wales. We discovered that around a third of all medicines were associated with an increased risk of dementia! This led us to explore possible reasons for these associations, generating hypotheses for future studies. Since then, SAIL-DeC has been used to study the effects of COVID-19 on care home residents, trends in antipsychotic prescribing in people with dementia, risk of falls in older people and to investigate how socioeconomic status affects care home admission in people living with dementia.
What does the future hold for SAIL-DeC?
SAIL-DeC is a “living” cohort, meaning that it is regularly refreshed with data updates. We hope that researchers around the world will continue to use SAIL-DeC to study the causes, predictors, treatment and prognosis of dementia. Over time, we hope to obtain linkage to additional datasets. A long-term goal is to obtain linked brain imaging data – this would create a very powerful research resource for studying neurological diseases.
How can researchers access SAIL-DeC for their research?
Researchers interested in using SAIL-DeC can submit an enquiry to the SAIL team. A SAIL analyst will then contact them to discuss their project feasibility and costs. For researchers interested in the relationship between COVID-19, dementia and cardiovascular diseases, they can apply for SAIL-DeC data via the British Heart Foundations’ CVD-COVID-UK/COVID-IMPACT consortium.
