Lower initial red blood cell count in cerebrospinal fluid predicts good functional outcome in patients with spontaneous subarachnoid haemorrhage

Abstract

Background and purpose: Red blood cell (RBC) degradation after subarachnoid haemorrhage (SAH) negatively affects functional outcome. Although the detection of RBCs in the cerebrospinal fluid (CSF) is a widely available part of neurological routine diagnostics, the prognostic value as a biomarker remains unclear. This study was undertaken to investigate whether CSF RBC count correlates with established radiological markers of SAH volume and whether the CSF RBC count can predict functional outcome in SAH patients.

Methods: A total of 121 consecutive spontaneous SAH patients were retrospectively analyzed. CSF was collected from external ventricular drain as part of routine diagnostic procedures. We used multivariable binary logistic regression to investigate associations between CSF RBC counts and functional outcome 3 months after SAH or hospital survival. Good functional outcome was defined as modified Rankin Scale ≤ 2.

Results: Patients' age was 60 ± 14 years, and the median admission Hunt & Hess grade (H&H) was 4. CSF samples were collected 2 days after intensive care unit admission. High CSF RBC counts positively correlated with radiological measurements for SAH volume, for example, modified Fisher score (p = 0.002) and Hijdra ventricle score (p = 0.016). Multivariable regression analysis adjusted for age, H&H grade, modified Fisher and Hijdra scores showed that low CSF RBC counts predicted hospital survival (per 100,000 CSF RBCs: adjusted odds ratio [adjOR] = 0.74, 95% confidence interval [CI] = 0.61-0.89, p = 0.001) and good functional outcome after 3 months (per 100,000 CSF RBC: adjOR = 0.76, 95% CI = 0.60-0.96, p = 0.020).

Conclusions: CSF RBC counts correlate with radiographic scores quantifying SAH volume and may serve as an early independent biomarker for hospital survival and good functional 3-month outcome in patients requiring ventriculostomy after SAH.

Keywords: cerebrospinal fluid; prognosis; red blood cells; subarachnoid haemorrhage.