Traumatic brain injury (TBI) can be defined as an alteration in brain function, or other evidence of brain pathology, caused by an external force. TBI is common worldwide and has been linked with subsequent suicide. Suicide in this population is suggested to be due to an interaction of internal and external stressors or through damage to parts of the brain where impulse and inhibition is controlled; though these causes are not conclusive. Current evidence of suicide risk in people with TBI is lacking, with existing studies suffering from major limitations such as small sample sizes or only in high-risk populations of TBI.
We will calculate the incidence of suicide (completed and attempted) following TBI in the general population of adults aged 18 years or older and compare their risk of suicide to people without TBI. We will also calculate the incidence of completed and attempted suicide separately.
Understanding the risk factors for suicide in people with TBI and which groups of TBI sufferers are more at risk will aid in developing and improving prevention services for TBI sufferers. Therefore, sex, age, ethnicity, substance abuse, pre-existing depression, type of TBI, and time from TBI will be investigated as potential risk factors. Additionally, sub-group analyses will be done to determine the risk of suicide across the following groups of people with TBI compared to people without TBI: male, female, 18–40-year-olds, 40 or above year olds, White-ethnic groups, non-White ethnic groups, lower socioeconomic status, upper socioeconomic status and those with pre-existing depression.
Traumatic brain injuries (TBI) are common in Europe, with an incidence rate as high as 694 per 100,000 people per year.1 Existing yet limited evidence suggest that people with TBI are at higher risk of suicide compared to people without TBI; however, the reasons for this are poorly understood, as are the potential risk factors and risk in the general population.
At present, existing evidence mainly focuses on populations that are prone to TBI such as war veterans.2 Whilst three population-based studies were completed in Denmark, Sweden and Taiwan, the former two investigated completed suicide risk3,4 and the latter investigated attempted suicide risk.5 To our knowledge, no population-based study exists that report the risk of combined completed and attempted suicide following TBI. It is also important to confirm their results using additional population-based databases to improve the global understanding of the relationship between TBI and suicide.
We will investigate the incidence of suicide (completed and attempted combined and separately) after TBI in adults aged 18 years or older. We will investigate key characteristics to determine risk factors of suicide after TBI. We will use Cox regression to investigate whether people with TBI experience a higher risk of suicide compared to people without TBI matched on sex, age (within 1 year) and geographical location; the same analysis and matching will be used to determine the risk between numerous sub-groups of people with and without TBI.
We will determine the exposure (TBI) through SNOMED codes in CPRD Aurum, Hospital Episode Statistics (HES) data will be used to define type of TBI, and HES data combined with Office of National Statistics (ONS) data will be used to define attempted and completed suicide.
We will measure the following outcomes:
- The incidence of suicide (completed and attempted) following TBI
- The incidence of completed suicide following TBI
- The incidence of attempted suicide following TBI
- The associated risk factors for suicide (completed and attempted) following TBI
- The risk of suicide (completed and attempted) in people with TBI compared to people without TBI
- The risk of suicide (completed and attempted) in sub-groups of people with TBI compared with the same sub-group of people without TBI
G. Neil Thomas - Chief Investigator - University of Birmingham
Tiffany Gooden - Corresponding Applicant - University of Birmingham
Anuradhaa Subramanian - Collaborator - University of Birmingham
Nicola Adderley - Collaborator - University of Birmingham
HES Admitted Patient Care;ONS Death Registration Data;Patient Level Index of Multiple Deprivation