Research has shown that people who are hospitalised with epilepsy have a three-fold increased risk of being hospitalised for self-harm. It is not known to what extent this risk is elevated when all people with epilepsy are included or self-harm events are recorded in primary care. Few studies have investigated the factors that influence risk of suicide and self-harm in people with epilepsy. It is important to identify these factors, in order to target preventative measures. There have been suggestions that some antiepileptic drugs (AEDs) may be associated with a higher or lower risk of suicide or self-harm but the current evidence is weak. As most people with epilepsy are treated with AEDs, it is important that we understand if any particular AEDs are associated with increased risk of suicide of self-harm. We will do this by comparing the risk of self-harm in people with epilepsy who use different AEDs. If certain AEDs do have an increased risk, this can be considered when deciding which AEDs are the most suitable to prescribe.
Objectives: i) Estimate the risk of self-harm in people with epilepsy vs. a comparison cohort; ii) identify risk factors for self-harm amongst people with epilepsy and iii) estimate the risk of self-harm associated with individual AEDs compared to valproate.
Methods: The risk of self-harm will be estimated in an incident epilepsy cohort vs. a comparison cohort with no history of epilepsy. From the incident epilepsy cohort, people who have a first self-harm event will be identified (cases) and a nested case-control study will be constructed. The risk of self-harm will be estimated in relation to the following exposures: mental illness, psychotropic medication, frequency of consultations, hospitalisation and AED utilisation. In a separate study, new users of AEDs will be identified from the incident epilepsy cohort and risk of self-harm associated with individual AED will be estimated compared to valproate.
Analysis: The matched cohort will be analysed by a stratified Cox proportional hazards model. Conditional logistic regression will be used to estimate the relative risk of self-harm for each exposure in the nested case-control study. Inverse-Probability of Treatment Weighting propensity scores will be used in a weighted Cox proportional hazards model to estimate hazard ratios for self-harm associated with each AED.
Darren Ashcroft - Chief Investigator - University of Manchester
Hayley Gorton - Corresponding Applicant - University of Manchester
Mark Lunt - Collaborator - University of Manchester
Matthew Carr - Collaborator - University of Manchester
Roger Webb - Collaborator - University of Manchester
HES Admitted Patient Care;ONS Death Registration Data;Patient Level Index of Multiple Deprivation