The researchers developed the ICCTUS score based on the SOFA (Sequential Organ Failure Assessment) score, which had previously demonstrated the ability to predict delayed infarctions after spontaneous subarachnoid hemorrhage (SAH). In this retrospective study, they evaluated 430 patients with SAH in a neurosurgical ICU over 10 years (68.14% female, mean age 56.8 ± 12.5 years) for whom data were available to calculate SOFA and ICCTUS scores. The median of both scores was 5, and the outcome was assessed by the modified Rankin scale (mRS) at 6 months. The SOFA score had an AUC of 0.76 in predicting adverse outcome, the WFNS AUC of 0.71, and the Hunt-Hess AUC of 0.64. The ICCTUS score, based only on central nervous, cardiovascular, and respiratory system parameters, achieved an AUC of 0.8 with a sensitivity of 0.74, specificity of 0.74, positive predictive value of 0.83, and negative predictive value of 0.62. Youden's index was 0.48 at the threshold of ≥ 3 points. The ICCTUS score was equal to or better than the standard score in predicting adverse outcome after SAH and may serve as an additional tool in the diagnosis of at-risk patients.