Prognostication Following Aneurysmal Subarachnoid Hemorrhage: The Modified Hunt and Hess Grading Scale

Area of Science:

• Neurosurgery
• Neurology
• Critical Care Medicine

Background:

• Aneurysmal subarachnoid hemorrhage (aSAH) requires accurate prognostication for optimal patient management.
• The traditional Hunt and Hess (tHH) scale is a standard but may lack precision in differentiating the most severe cases.
• Brainstem dysfunction, indicated by low Glasgow Coma Scale (GCS) scores, significantly impacts aSAH outcomes.

Purpose of the Study:

• To introduce and validate a modified Hunt and Hess (mHH) grading scale for improved prognostication in aSAH.
• To enhance the differentiation of severe aSAH patients by incorporating GCS scores into the tHH scale.
• To compare the diagnostic performance of the mHH scale against the tHH scale for predicting poor outcomes in aSAH.

Main Methods:

• Retrospective analysis of weighted aSAH hospitalizations from the National Inpatient Sample (2015-2019).
• Stratification of patients by tHH and the proposed mHH grades, with mHH grade 5 defined by tHH grade 5 and GCS 3-5.
• Comparison of diagnostic performance measures, including discrimination (c-statistic), specificity, and positive predictive value (PPV), using the NIS-SAH Outcome Measure (NIS-SOM).
• External validation of the mHH scale using a prospectively maintained aSAH registry.

Main Results:

• Among 6130 aSAH hospitalizations, 36% were tHH grade 5, with 35% of these meeting mHH grade 5 criteria (GCS 3-5).
• The mHH scale demonstrated superior discrimination for poor outcomes compared to the tHH scale (c-statistic 0.793 vs. 0.780).
• mHH showed significantly improved specificity (0.929 vs. 0.304) and PPV (0.949 vs. 0.827) over tHH.
• External validation confirmed excellent discrimination for mHH (c-statistic 0.835) with high specificity (0.950) and PPV (0.905).

Conclusions:

• The modified Hunt and Hess (mHH) scale offers a more accurate and specific method for prognostication in aneurysmal subarachnoid hemorrhage.
• The mHH scale effectively differentiates high-severity aSAH patients, particularly those with brainstem dysfunction.
• This enhanced grading system may improve clinical decision-making and patient outcomes in severe aSAH cases.