Association Between Craniotomy and Outcomes in Patients With Acute Subdural Hematoma: Analysis of a Nationwide Trauma Registry in Japan

BACKGROUND AND OBJECTIVE: The benefits of surgery remain unclear in less severe cases of acute subdural hematoma (ASDH). We aimed to investigate the association between surgical intervention and outcomes in patients with ASDH. METHODS: This multicenter cohort study analyzed data from the Japan Trauma Data Bank between January 2019 and December 2023. Patients age 18 years and older with large supratentorial ASDH (>50 cm3, >1 cm thick) and a Glasgow Coma Scale (GCS) score of 6 to 15 at hospital arrival were included. One-to-one propensity score matching was performed to compare patients who underwent craniotomy with those who did not. Study outcomes included survival to hospital discharge and favorable neurological outcomes. RESULTS: Overall, 1808 patients (median age, 79 years; 64.9% male) from 83 hospitals were included, and 46.6% underwent craniotomy. Craniotomy rates ranged from 0.0% to 83.3% (median, 46.2%) across hospitals. Propensity score matching identified 610 matched patients with and without craniotomy. Patients who underwent craniotomy had a significantly higher survival rate (77.2% vs 62.6%; within-hospital difference, 14.7%; 95% CI, 9.6%-19.8%); however, no significant difference was observed in the proportion of favorable neurological outcomes at discharge (16.1% vs 17.9%; within-hospital difference, -1.9%; 95% CI, -7.5% to 3.7%). Subgroups analyses demonstrated significant interactions between craniotomy and both age and GCS scores, with greater benefit observed in patients age 65 years and older (difference, 3.9% [<65 years] vs 17.1% [≥65 years]) and in those with a GCS score of 6 to 12 (difference, 27.8% [GCS 6-12] vs -6.1% [GCS 13-15]). CONCLUSION: In patients with large ASDHs, craniotomy was significantly associated with improved survival, particularly among patients age 65 years and older and those with lower GCS scores (6-12). A uniform approach based solely on hematoma thickness may be suboptimal. Instead, surgical decision-making needs to adopt a more individualized approach that incorporates age and neurological severity.