<p>Objectives: With the rapid expansion of the elderly population, there has been an increase of the number of elderly traumatic brain injury (TBI) patients in Japan. In this study, transition of aggressive treatment and patient outcome in geriatric TBI patients were analyzed with the data of Japan Neurotrauma Data Bank Projects (JNTDB) 1998 (P1998), 2004 (P2004), 2009 (P2009), and 2015 (P2015). The prognostic factors in geriatric TBI were also examined.</p><p>Methods: Of 4,527 cases registered in the four JNTDB projects, 1,879 geriatric TBI cases (≥65 years old) were enrolled in this study. The clinical features, aggressive treatment defined as surgical procedure and/or inten­sive temperature treatment including intracranial pres­sure monitoring, and outcomes based on Glasgow Outcome Scale on discharge were compared among four study projects. Moreover, to clarify the prognostic factors in geriatric TBI patients, logistic regression analysis was performed.</p><p>Results: The percentage of geriatric TBI population was significantly increased throughout three projects (P1998; 30.1%, P2004; 34.6%, P2009; 43.9%, P2015; 53.6%, p<0.0001). Aggressive treatments including sur­gical management and intentional temperature man­agement were performed in 69.3% of geriatric patients in P2015 and this percentage was significantly increased from P1998 to P2015. Less invasive method, like as trephination and mormotermic targeted tem­perature management, were tend to choose for geriatric patients. With these efforts for geriatric TBI care, mortality ratio was significantly decreased (P1998; 62.8%, P2015; 44.7%, p<0.0001). On the other hand, the percentage of severe disability patient was still significantly increased. The percentage of dependent survivors were also increased (P1998; 23.2%, P2015; 39.1%, p<0.0001). Patient Age ≥ 75, Injury Severity Score ≥ 25, Glasgow Coma Scale (GCS) ≤ 8, pupil abnormality, existence of traumatic subarachnoidal hemorrhage (SAH), and existence of intraventricular hemorrhage (IVH) were clarified as the unfavorable prognostic factors. IVH was the strongest unfavorable prognostic factor in geriatric TBI patients (OR 3.99, 95%CI 2.05 – 7.76, p<0.0001).</p><p>Conclusion: Our result revealed that the aggressive, less invasive treatments provided less mortality in geriatric TBI patients. On the other hand, these efforts did not result in better outcome in this popula­tion. For the prompt decision making, patient age, initial GCS, and anatomical severity including SAH and IVH should be helpful as the functional prognostic factors.</p><p>Reconsideration of multimodal treatment strategy, including rehabilitation, seemed to be established.</p>