The lifetime prevalence of hospitalised head injury in Scottish prisons: A population study

Background: There is mounting evidence that associates brain injury and offending behaviour, and there is a need to understand the epidemiology of head injury in prisoners in order to plan interventions to reduce associated disability and risk of reoffending. This is the first study to determine the lifetime prevalence of hospitalised head injury (HHI) in a national population of current prison inmates. In addition characteristics of prisoners with HHI and were compared to prisoners without HHI to discover whether those with HI differed demographically. Methods: Whole life hospital records of everyone aged 35 years or younger and resident in a prison in Scotland on a census date in 2015 were electronically linked via their unique NHS identifier and checked for ICD-9 and 10 codes for head injury. Using a case-control design, these data were compared with a sample from the general population matched 3:1 for age, gender and area-based social deprivation. Comparison of demographic variables was made between prisoners with and without HHI. Results: HHI was found in 24.7% (1,080/4,374) of prisoners and was significantly more prevalent than found in the matched general population sample (18.2%; 2394/13122; OR 2.10; 95%CI 1.87, 2.16). The prevalence of HHI in prisoners and controls was similar with the exception of a higher risk of HHI in prisoners in lower deprivation quintiles. Having three or more HHI was more common in prisoners (OR 3.04; 95%CI 2.33, 3.97) as were HHI with ICD codes for intracranial injuries (OR 1.81; 95% CI 1.54, 2.11), suggesting that more severe HHI is more prevalent in prisoners than the general population. The distributions within demographic variables and the characteristics of HHI admissions in prisoners with and without a history of HHI were similar. Conclusion: Prisoners in Scotland aged 35 years or younger have a higher lifetime prevalence of HHI than the general population and are more likely to have had repeated HI or intracranial injuries. Further work is required to elucidate the correspondence between self-report of HI and hospitalised records and to ascertain persisting effects of HI in prisoners and the need for services to reduce associated disability and risk of reoffending.