Association between systemic inflammation biomarkers and outcomes in patients with aneurysmal subarachnoid hemorrhage

Aneurysmal subarachnoid hemorrhage (aSAH) is a devastating condition that is associated with cerebral and systemic inflammation. C-reactive protein (CRP) and neutrophil-to-lymphocyte ratio (NLr) are easily available biomarkers of systemic inflammation. Therefore, we aimed to assess the impact of elevated CRP and NLr on aSAH outcomes. This retrospective, single-center study included adult patients admitted with aSAH to the intensive care unit (ICU) from January 2007 to December 2023. We recorded serum CRP and NLr levels during the first 7 days of ICU stay. An unfavorable neurological outcome at 3 months was defined as a Glasgow Outcome Scale (GOS) score of 1-3. A total of 547 patients were included in the study; 250 (45.7%) experienced unfavorable outcomes (UOs), and 140 (25.6%) developed delayed cerebral ischemia (DCI). Patients with unfavorable outcomes had higher levels of CRP from days 2 to 7 after SAH (p = 0.001) and higher NLr (p = 0.06) than those with favorable outcomes (FOs). In a multivariate logistic regression model, the highest CRP value (OR: 1.003, 95% CI: 1.001-1.005) and the highest NLr value (OR: 1.025; 95% CI: 1.001-1.050) in the first 7 days after SAH were independently associated with the occurrence of unfavorable outcomes. The highest NLr value was also associated with the development of DCI (sHR: 1.02, 95% CI: 1.01-1.03). In conclusion, high CRP and NLr values have a significant prognostic role in aSAH patients, reinforcing the importance of inflammation as a potential mechanism of secondary brain injury.