Authors: Yi-Ren Chen, MD; Eli Johnson; Beatrice Ugiliweneza; Maxwell Boakye; Victor Tse (Stanford, CA)

Introduction: Intracranial gunshot wounds (GSW) are often fatal, with most patients dying before intervention can occur. Surgical management, when indicated, results in decreased mortality. However, our knowledge of the outcomes and economic costs of intracranial GSW remains limited. Methods: We conducted a retrospective analysis using the longitudinal claims Truven MarketScan® database from 2000 to 2016. Mortality was the primary outcome of interest and complications, length of stay and payment were secondary outcomes. Multivariable logistic and linear regression was performed to assess the relationship between age, gender, insurance type and the number of comorbidities to the outcomes measured. Results: We identified 418 patients (Median age = 26.0y, IQR= 18, 44; 23.4% female) who received craniotomy or craniectomy for intracranial GSW. Mortality occurred in 50 patients (11.96%) and 286 patients (68.42%) experienced complications. The median length of stay was 10 days (IQR=4; 22days) and cost was $62,574.00 (IQR=$28,111.00; $143,980.00). Increasing age by 1-year increments demonstrated increases in complications (OR=1.023; 95% CI=1.007 - 1.038), mortality (OR=1.023; 95% CI=1.002 - 1.044), length of stay (RR=1.01; 95% CI=1.003 - 1.017) and payment (RR=1.01; 95% CI= 1.002 - 1.017). When comparing Medicaid to commercial insurance, patients with Medicaid had a longer length of stay (RR=1.299; 95% CI=1.049 - 1.608) and less payment (RR=0.571; 95% CI=0.454 - 0.718). Finally, increases in the Elixhauser index by 1-comorbitiy increments was associated with increased complications (OR=1.233; 95% CI=1.024 - 1.485), length of stay (RR=1.292; 95% CI=1.188 - 1.405) and payment (RR=1.208; 95% CI=1.104 - 1.322). Conclusion: Although these findings must be interpreted in the context of the limitations inherent to studies using national administrative data, the current study provides additional insight into the relationship between patient characteristics and outcomes after surgery for intracranial GSW.