Antipsychotic initiation and risk of diabetes in older statin users: a patient-level interrupted time series analysis

PI Title: Philip Stone

Co- PI's: Dr. Juan Carlos Bazo-Alvarez & Irene Petersen

Lead member: UCL

What is the problem?
Approximately half of 70- to 80-year-olds in the UK are prescribed a statin medication to reduce cholesterol and risk of heart disease. There is strong evidence for the benefits of statins with regard to preventing heart disease, but there is also some evidence that statin use may increase blood sugar, leading to an increased risk of developing type-2 diabetes.
In the UK, approximately 7% of over 65-year-olds live with dementia and as the population ages, the number of people with dementia is estimated to reach 1.4 million by 2040. Many people with dementia experience severe episodes of distress and/or agitation and antipsychotic medication is often prescribed to help with this. In recent years, many have been prescribed antipsychotic medications such as olanzapine, quetiapine, or risperidone. However, these antipsychotics can
cause raised blood sugar levels and increase the risk of developing diabetes.
It is not known whether statin users who then go on to take a second-generation antipsychotic medication are at further increased risk of type-2 diabetes than people who only take a statin.

What is the aim?
We want to determine if people over the age of 70 who have been taking a statin medication for at least one year and then begin to take an antipsychotic medication may be more likely to develop diabetes than someone who just takes a statin medication.

What will we do?
We will use anonymised data from GP records to find out how many statin users over the age of 70 start taking an antipsychotic medication each year. Within this group we will compare the change in their blood sugar levels 1 year before and 1 year after they start taking an antipsychotic medication. This will allow us to see if starting to take an antipsychotic medication while already taking a statin, will lead to a steeper increase in blood sugar than would have been expected were they to continue on just a statin. We will complete the analysis separately in men and women to explore if the effect of the medications is different between the sexes.

What difference will this make?
The findings from this analysis have the potential to help us understand whether there is any additional risk of developing diabetes to older people by taking an antipsychotic while on statin treatment. This would help fill a gap in current knowledge on the combined use of statins and antipsychotics and could potentially lead to an update in prescribing guidelines for antipsychotics in older statin users. This may lead to doctors being more cautious about prescribing the two medications together and ultimately reduce the number of people who develop diabetes.