Impact of pre-existing dementia on neurosurgical intervention and outcomes in older patients with head injury: an analysis of a nationwide trauma registry in Japan

Background: Dementia is a common comorbidity in older patients with traumatic brain injury (TBI), potentially affecting their care processes and outcomes. However, the impact of pre-existing dementia on TBI remains unclear as research on TBI often excludes older adults with comorbidities. This study aimed to investigate the association between pre-existing dementia and outcomes in older patients admitted to hospitals after TBI.

Methods: This observational study included patients aged ≥ 65 years with TBI who were identified from the Japan Trauma Data Bank between January 1, 2019, and December 31, 2021. Associations between pre-existing dementia and outcomes were assessed using multivariable logistic regression analysis. The primary outcome was survival at discharge. Secondary outcomes were neurosurgical interventions and discharge to home.

Results: In total, 16,270 patients from 175 hospitals were analyzed. Of these, 1,750 (10.8%) had pre-existing dementia, and 13,520 (83.1%) survived to discharge. No significant association was observed between pre-existing dementia and neurosurgical interventions and survival at discharge. In contrast, pre-existing dementia was associated with a significantly lower likelihood of being discharged to home. Subgroup analysis revealed interactions between pre-existing dementia and the subgroups, showing adverse impact in relatively younger patients and those without severe head injury.

Conclusions: Patients with pre-existing dementia had similar chances for neurosurgical intervention and survival at discharge than their counterparts without dementia. However, pre-existing dementia was associated with a significantly lower likelihood of being discharged to home, especially in relatively younger patients and those without severe head injury. Therefore, recognizing the risks within this population and taking measures to facilitate social reintegration is necessary.