Association Between Intensive Care Unit Admission Practices and Outcomes in Patients with Isolated Traumatic Subarachnoid Hemorrhage: A Nationwide Inpatient Database Analysis in Japan

Patients with traumatic brain injury associated with intracranial hemorrhage are commonly admitted to the intensive care unit (ICU); however, the need for ICU care for patients with isolated traumatic subarachnoid hemorrhage (tSAH) remains unclear. We aimed to investigate the association between the ICU admission practices and outcomes in patients with isolated tSAH.

This observational study used a nationwide administrative database in Japan. We identified patients with isolated tSAH from the Japanese Diagnostic Procedure Combination inpatient database from July 1, 2010, to March 31, 2020. The primary outcome was in-hospital mortality, whereas the secondary outcomes were neurosurgical interventions, activities of daily living at discharge, and total hospitalization cost. We performed a risk-adjusted mixed-effect regression analysis to evaluate the association between hospital-level ICU admission rates and study outcomes. The ICU admission rates were categorized into quartiles: lowest, middle-low, middle-high, and highest. Moreover, we assessed the robustness of the results with a patient-level instrumental variable analysis.

Of the 61,883 patients with isolated tSAH treated at 962 hospitals, 16,898 (27.3%) patients were admitted to the ICU on the day of admission. Overall, 2465 (4.0%) patients died in the hospital, and 783 (1.3%) patients underwent neurosurgical interventions. There was no significant difference between the lowest and highest ICU admission quartile in terms of in-hospital mortality (3.7% vs. 4.3%; adjusted odds ratio 0.93; 95% confidence interval [CI] 0.78–1.10), neurosurgical interventions, and activities of daily living at discharge. However, the total hospitalization cost in the lowest ICU admission quartile was significantly lower than that in the highest quartile (US $3032 vs. $4095; adjusted difference US $560; 95% CI 33–1087). The patient-level instrumental variable analysis did not reveal a significant difference in in-hospital mortality between the patients who were admitted to the ICU and those who were not (risk difference 0.2%; 95% CI − 0.1 to 0.5).

There was no significant association between the ICU admission practices and outcomes in patients with isolated tSAH, whereas higher ICU admission rates were associated with significantly higher hospitalization costs. Our results provide an opportunity for improved health care allocation in the management of patients with isolated tSAH.