Long-term Risk of Hydrocephalus Following Traumatic Brain Injury and Hemorrhagic Stroke: A Nationwide Cohort Study in South Korea

Objective: This study aimed to provide evidence on the long-term risk and comparative outcomes of hydrocephalus, a serious complication of traumatic brain injury (TBI) and hemorrhagic stroke (HS). Setting: The study analyzed data from the Korean National Health Insurance Service-National Sample Cohort (2002-2013). Data from 2002 to 2005 were used as a washout period, and cases identified from 2005 to 2013 were included in the analysis. New-onset hydrocephalus was defined as at least 2 medical claims with code G91 of the International Classification of Diseases, 10th revision. Participants: A total of 17 331 patients diagnosed with TBI or HS were matched with 86 655 controls using propensity score matching. Design: A retrospective cohort study comparing patients with TBI or HS to matched controls. Main Measures: Crude incidence rates (IRs), incidence rate ratios (IRRs), and adjusted hazard ratios were estimated using time-stratified Cox models over a 9-year follow-up period. Results: The incidence of hydrocephalus was significantly higher in the case group (IR, 1.88 per 1000 person-years) than in the control group (IR, 0.10). The overall IRR was 19.64 (95% confidence interval [CI], 13.30-29.00). Stratified analyses showed an IRR of 8.21 (95% CI, 5.32-12.68) for TBI and 35.49 (95% CI, 20.53-61.36) for HS. The adjusted hazard ratios declined over time but remained elevated for up to 6 years post-diagnosis. Risk was high in younger individuals, smokers, and alcohol users. Conclusion: TBI and HS are associated with a substantially increased long-term risk of hydrocephalus, especially in the early years following diagnosis. HS confers a greater risk than TBI. These findings underscore the need for prolonged surveillance in high-risk individuals and appropriate management of hydrocephalus.