Clinical Significance of Serial Measurements of Interleukin-6 and High-Sensitivity C-Reactive Protein as Early Predictor of Poor Neurological Outcome in Aneurysmal Subarachnoid Haemorrhage

Introduction: The inflammatory events are implicated in the pathophysiology of subarachnoid haemorrhage (SAH) and secondary brain injury. The goal of this study was to determine the role of interleukin-6 (IL-6) and high-sensitivity C-reactive protein (hsCRP) as an early predictor of the poor neurological outcome at 6 months in individuals with SAH. Methods: In this prospective, observational study of consecutive patients with aneurysmal SAH included over 1 year. Peak IL-6 and hsCRP were used as an indicator of the inflammatory response. Initial IL-6 and hs-CRP levels were collected within 12 h from admission and then for the next consecutive 7 days. The primary outcome was neurological status at 6-month follow-up assessed with the Modified Rankin Scale (0–6) with a score with or higher than 3 labelled as poor outcome. Logistic regression analyses were used to evaluate the associations between the peak serum IL-6 and hs-CRP levels and the neurological outcome. Results: The median peak levels of both markers were significantly higher in the poor outcome group on all 7 days. A significant correlation was seen between peak IL-6 and poor Hunt and Hess grade (P = 0.006), infarction (0.033) and systemic infection (0.03), whereas peak hsCRP had a correlation with rebleed (P = 0.017) and clipping (P = 0.032). Significant risk factors for the poor outcome were poor Hunt and Hess grade (P < 0.000) and high Fisher grades (P = 0.021) and peak IL-6 levels (P = 0.014) on regression analysis. Conclusion: The serial measurements of inflammatory markers IL-6 and hsCRP may be used to predict the neurological outcome in aSAH patients. The peak IL-6 levels correlated significantly with poor neurological outcome. Although hsCRP was elevated in patients with the poor outcome, it was statistically non-significant, suggesting a non-specific inflammatory stress response.