Hospital Volume-Outcome Relationship in Severe Traumatic Brain Injury: A Nationwide Observational Study in Japan

The hospital volume-outcome relationship in patients with severe traumatic brain injury (TBI) remains unclear. This study investigated the association between the volume of patients with severe TBI and in-hospital mortality.This observational study identified patients with severe TBI (Glasgow Coma Scale score9 and Abbreviated Injury Scale head score ≥3) from the Japan Trauma Databank (2010-2018). Hospitals were grouped on the basis of annual patient volume as follows: low-volume (4-19 patients/year); middle-volume (20-35 patients/year); and high-volume (36-51 patients/year) groups. The association between hospital volume categories and in-hospital mortality was examined using a multivariate mixed-effect logistic regression analysis. A subgroup analysis was performed based on the presence of severe extracranial injuries.A total of 11,344 patients from 64 hospitals were included. The median age of the patients was 57 years (interquartile range, 40-77), and 7933 (70.0%) patients were men. A total of 4879 (43.1%) patients died in the hospital. The medium-volume (adjusted odds ratio [OR], 0.76; 95% confidence interval [CI], 0.62-0.93) and high-volume (adjusted OR, 0.69; 95% CI, 0.52-0.94) groups were significantly associated with lower in-hospital mortality. The subgroup analysis revealed that the medium-volume (adjusted OR, 0.70; 95% CI, 0.54-0.92) and high-volume (adjusted OR, 0.64; 95% CI, 0.42-0.96) groups were significantly associated with lower in-hospital mortality for isolated TBI patients.Higher hospital volumes were significantly associated with lower in-hospital mortality after severe TBI. Regionalization and referral to higher-volume hospitals are beneficial for severe TBI patients.