The proportion of the older population in Japan (the percentage of those aged ≥65 in the total population as of September 15, 2020) is at its highest at 28.7%, and it is expected to continue rising in the future. According to the Japan Head Injury Data Bank, the number of head injuries among older people in Japan is increasing yearly [1]. Additionally, in isolated head injuries, age is an independent prognostic factor [2], and head injuries among older people are associated with poor life prognosis and functional outcomes. This may be due to the anatomical and physiological vulnerability of brain tissue in older people. “Talk and deteriorate” is a term used to describe the clinical course where a patient, despite having a relatively good level of consciousness during the initial examination, subsequently deteriorates. This phenomenon is more common among older people [3].

The severity of head injury is typically indicated by the degree of disturbance of consciousness following injury. Generally, mild head injury is defined by a Glasgow Coma Scale (GCS) score of 13–15 at the time of examination.

The guidelines from the European Federation of Neurological Societies (EFNS) [4] and other reports have highlighted several useful criteria for performing CT in patients with minor head injuries [[5], [6], [7]]. Age is often cited as a risk factor; therefore, CT should be performed in all older patients.

Studies have examined the risk factors associated with acute traumatic lesions on head CT in older patients with minor head injuries [8].

In older people, outcomes such as death, neurosurgical interventions, endotracheal intubation, prolonged hospitalization, internal medicine-related treatments like discontinuation of antithrombotic agents, and administration of antihypertensive or antiepileptic drugs are considered significant outcomes in terms of their complications and impact on prognosis. However, no studies have examined these risk factors in older people with minor head injury.

In older patients with minor head injury, traditional outcome metrics that focus only on the presence or absence of lesions on imaging studies is insufficient. Therefore, we propose expanding outcome metrics to be more clinically relevant and reflective of real-world clinical practice.

The aim of this study is to examine the risk factors for clinically important traumatic brain injury (ciTBI1: death, neurosurgical intervention, endotracheal intubation, internal medicine-related intervention, and hospitalization for >2 nights) in minor head injuries in older people.