In Reply: Interhospital Variation in Operative Intervention for Firearm-Related Penetrating Traumatic Brain Injury and Associations With Inpatient Mortality

To the Editor: We thank Beucler et al for their thoughtful comments regarding our recent study examining interhospital variation in operative intervention for firearm-related penetrating traumatic brain injury (pTBI).1,2 Their perspective, particularly from a military neurosurgical context, highlights important systems-level considerations relevant to the interpretation and application of our findings. First, we appreciate the authors' inquiries regarding trauma center infrastructure and neurosurgical organization. In our study, we performed a subanalysis of hospital-level characteristics and did not observe significant differences in trauma center designation, hospital size, or teaching status across quartiles of operative tendency. However, we agree that more granular institutional factors, such as neurosurgical staffing models, operative availability, and provider experience, are not captured within the American College of Surgeons Trauma Quality Improvement Program (TQIP) data set. Similar hospital-level variation has also been observed in blunt traumatic brain injury, including in our prior work demonstrating meaningful interhospital differences in outcomes.3 Together, these findings suggest that unmeasured system-level factors likely contribute to variation in pTBI management. Relatedly, we concur that continuous availability of an on-site senior neurosurgeon may meaningfully influence operative decision making in emergent settings. However, detailed information regarding neurosurgical call structure, in-house attending coverage, and regional referral practices is not captured within the TQIP data set. Despite adjustment for key clinical variables, including Glasgow Coma Scale, pupillary reactivity, injury severity, and radiographic findings, substantial interhospital variation persisted in our hierarchical model (median odds ratio 1.33), suggesting that structural and organizational differences in care delivery likely contribute to observed practice variation. Importantly, although interfacility transfer was independently associated with improved survival in our cohort and has similarly been incorporated into prognostic frameworks such as the SPIN score,4 transfer rates themselves did not significantly differ across hospital quartiles. We agree that this finding is notable and may reflect differences in institutional thresholds for operative intervention, triage philosophy, or neurosurgical decision making after transfer rather than differences in transfer access alone. Collectively, these observations further support the importance of coordinated regional neurotrauma systems and highlight the need for future studies incorporating more granular systems-level data regarding neurosurgical coverage and referral infrastructure. Next, we further agree that projectile trajectory is a key determinant of prognosis in pTBI that has been well described in prior literature.5 However, TQIP does not contain sufficiently granular radiographic detail to characterize ballistic trajectories or apply trajectory-based constructs such as the “zona fatalis.” We therefore relied on available imaging proxies, including midline shift and categorized patterns of intracranial injury, which are incorporated into contemporary management frameworks and large-scale studies.6 Notably, markers of mass effect such as midline shift >5 mm were strongly associated with operative intervention in our cohort, supporting their clinical relevance in surgical decision making. Future studies integrating detailed imaging review with large-scale data sets will be important to better define the role of trajectory in operative selection. Finally, we additionally appreciate the authors' discussion regarding military neurosurgical experience, telemedicine-supported cranial trauma care, and evolving international management guidelines for pTBI. These perspectives are highly relevant, particularly as contemporary efforts by organizations such as the Brain Trauma Foundation seek to refine evidence-based recommendations for penetrating brain injury management, such as in the second edition guidelines for the management of pTBI published earlier this year.7 Although TQIP does not identify hospital military affiliation or characterize institutional wartime neurosurgical experience, we agree that differences in familiarity with severe ballistic cranial trauma, operative aggressiveness, and multidisciplinary neurotrauma infrastructure may plausibly contribute to the interhospital variation observed in our cohort. Importantly, our findings demonstrated that hospitals with higher operative tendency were associated with improved survival, including among patients presenting with one or no reactive pupils, a population often considered to have limited operative candidacy. These findings align with emerging literature suggesting that carefully selected patients with severe pTBI may benefit from operative intervention despite historically pessimistic prognostic assumptions.8 We likewise agree that continued refinement of contemporary pTBI management algorithms, including incorporation of prognostic tools such as the SPIN score, will be important in promoting more standardized and evidence-based neurosurgical decision making across trauma systems. In conclusion, we are grateful to Dr Beucler and colleagues for their thoughtful review of our work and insightful perspectives. Their comments highlight important clinical and systems-level factors not captured in large administrative data sets and reinforce the central finding of our study: that meaningful variability exists in the operative management of pTBI, with important implications for patient outcomes. Addressing this variability through integrated clinical, radiographic, and systems-level research will be essential to optimizing care for this challenging patient population.