Risk of Shunting after Aneurysmal Subarachnoid Hemorrhage: A Collaborative Study and Initiation of a Consortium

Background and Purpose - Shunt dependent hydrocephalus after aneurysmal subarachnoid hemorrhage (aSAH) is a common sequela that may lead to poor neurological outcome and predisposes to various interventions, admissions, and complications. We reviewed post-aSAH shunt dependency in a population-based sample and tested the feasibility of a clinical risk score to identify subgroups of aSAH patients with increasing risk of shunting for hydrocephalus. Methods - A total of 1533 aSAH patients from the population-based Eastern Finland Saccular Intracranial Aneurysm Database (Kuopio, Finland) were used in a recursive partitioning analysis to identify risk factors for shunting after aSAH. The risk model was built and internally validated in random split cohorts. External validation was conducted on 946 aSAH patients from the Southwestern Tertiary Aneurysm Registry (Dallas, TX) and tested using receiver-operating characteristic curves. Results - Of all patients alive ≥14 days, 17.7% required permanent cerebrospinal fluid diversion. The recursive partitioning analysis defined 6 groups with successively increased risk for shunting. These groups also successively risk stratified functional outcome at 12 months, shunt complications, and time-to-shunt rates. The area under the curve-receiver-operating characteristic curve for the exploratory sample and internal validation sample was 0.82 and 0.78, respectively, with an external validation of 0.68. Conclusions - Shunt dependency after aSAH is associated with higher morbidity and mortality, and prediction modeling of shunt dependency is feasible with clinically useful yields. It is important to identify and understand the factors that increase risk for shunting and to eliminate or mitigate the reversible factors. The aSAH-PARAS Consortium (Aneurysmal Subarachnoid Hemorrhage Patients' Risk Assessment for Shunting) has been initiated to pool the collective insights and resources to address key questions in post-aSAH shunt dependency to inform future aSAH treatment guidelines.