Variation in capability, organisational structure, and treatment processes for critically ill adults with moderate-to-severe traumatic brain injury in Australia and New Zealand.

Objective: To characterise between-centre variation in capability, organisational structure, and treatment processes for adults with moderate-to-severe traumatic brain injury (msTBI) admitted to intensive care (ICU) in Australia and New Zealand (ANZ). Design: Cross-sectional questionnaire supplemented by linked Australian and New Zealand Intensive Care Society CORE Critical Care Resources Registry descriptors. Setting: ANZ ICUs treating adults with msTBI, October-December 2025. Main outcome measures: Variation in organisational structure and capability, ICU treatment processes, neuroprognostication, withholding or withdrawal of life-sustaining therapy, and fulfilment of selected Australian TBI Quality Indicator Set elements. Heterogeneity was assessed using the index of qualitative variation (IQV) for nominal items and Leik's dispersion for ordinal items; values <0.3 were considered low, 0.3-0.7 moderate, and >0.7 substantial. Results: Moderate or substantial heterogeneity was observed in 39 of 74 measured items (53%). Substantial heterogeneity included neurocritical care subspecialty expertise (IQV 1.00), perceived devastating traumatic brain injury management (IQV 0.99), cerebrospinal fluid drainage timing (IQV 0.93), withholding or withdrawal of life-sustaining therapy decision-making processes (IQV 0.86), arterial transducer zero level for cerebral perfusion pressure calculation (IQV 0.82), haemoglobin targets (Leik's dispersion 0.81), and post-ICU follow-up interval (IQV 0.81). Low heterogeneity in several advanced neuromonitoring and neuroprognostication modalities reflected consistent non-use or unavailability. Fulfilment of the six measured Australian TBI Quality Indicator Set indicators ranged from 2/6 to 5/6 across centres. Conclusions: Among ANZ ICUs providing care for adults with msTBI, moderate or substantial variation was evident in over half of measured organisational and clinical aspects of care. These findings identify targets for research and quality improvement and highlight centre variation as a potential modifier of patient outcomes.