Inter-Rater Reliability of Subarachnoid Hemorrhage Radiological Grading Scales: A Systematic Review and Meta-Analysis

Background: Subarachnoid hemorrhage (SAH) has high mortality and disability rates. The timely and precise assessment of SAH severity is of critical importance in predicting life-threatening complications. Several CT-based radiological grading systems have been proposed, but a comprehensive meta-analysis of their inter-rater reliability (IRR) has not been conducted. Methods: This study followed the guidelines of Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA). Two authors performed a systematic search of original articles in the PubMed database. Methodological quality of the studies was assessed using the Quality Appraisal of Reliability Studies (QAREL). Meta-analyses of Cohen's kappa and intra-class correlation coefficient (ICC) were performed using R packages "metafor" and "meta". Results: A systematic literature analysis was performed for twenty articles that met the inclusion criteria. The methodological quality was moderate in 14 of 20 studies; five studies were of low quality. Only eight articles were suitable for meta-analysis. Cohen's kappa of the binarized Fisher scale was 0.85 (95% CI 0.70-0.93), though it was based on only two studies and 109 patients. The Hijdra scale had an ICC of 0.75 (95% CI 0.29-0.93). The original and modified Graeb scales proposed for the assessment of concomitant intra-ventricular hemorrhage demonstrated ICC of 0.83 (95% CI 0.59-0.94) and 0.93 (95% CI 0.84-0.97), respectively. For other scales, meta-analysis was not possible due to incomplete reporting or single evaluations. Conclusions: The current evidence on IRR of radiological grading scales for SAH is limited, emphasizing the need for further high-quality research to validate their reliability and clinical applicability.