In this study, we derived and validated a composite EBI risk score. In addition to confirming the importance of EBI in determining long-term SAH recovery, the risk score could be used for patient selection or risk stratification in future clinical trials. The score was derived and validated in 2 independent cohorts, highlighting its ability to perform across separate patient populations. Future studies should focus on validating the application of EBI in clinical settings, examining other biomarkers in addition to sST2, and deepening our understanding of the pathophysiologic factors that lead to EBI and impact patient outcomes.