Individual-level stroke risk prediction after risperidone treatment in dementia

One of the main symptoms of dementia is memory loss. Other symptoms include agitation/aggression, seeing things that aren’t there and falsely believing others are trying to harm you. These symptoms make living with dementia much more difficult.

Helping these symptoms improve is very important and we know that drugs should only be used as a last resort for people with the most severe symptoms. The only drug licensed for this use in the UK is called risperidone. Even though it should be a last resort, prescription of risperidone is common. There is evidence that it helps some people, but it has severe side effects. One of the most serious of these is stroke. Stroke is caused when clots in blood vessels cut of the supply of blood to the brain. It is likely that risperidone causes hundreds of strokes per year in people with dementia. Using risperidone safely to keep stroke risk low is a priority because it is the only licensed drugs for these symptoms. A big problem is that we have no way of knowing whether a specific person will have a stroke if they take risperidone. This is recognised in official guidance which states that it is "not possible to know in advance what will happen to any individual person".

We are going to look at GP data from thousands of people and compare two groups:

• Group 1: people with dementia who have been prescribed risperidone
• Group 2: people with dementia who have never been prescribed risperidone.

We will then look at how often strokes happen in these groups. Then we will find out if parts of people’s medical history make it more likely that they will have a stroke if they take risperidone.

We will also do interviews and focus groups with people with dementia, their relatives/friends, care home staff and doctors. This is because we want to know people’s attitudes towards risperidone use in dementia. Understanding this will mean that the results of our study can be used in the most effective way possible to benefit patients. This will include writing new guidance for doctors and carers.

We will involve the public in our research by forming a lay advisory group who will help guide the research and co produce the findings. They will also help us publicise the research findings to the general public.

We hope the study findings will be used by doctors to help make prescribing risperidone safer for people with dementia.