Hunt and Hess classification of subarachnoid hemorrhage
The Hunt and Hess classification enables classification of the severity of a subarachnoid hemorrhage and predicts its mortality.
Research authors: Hunt WE, Hess RM
Details Formula Study characteristics Files & References
Model author
Model ID
Revision date
MeSH terms
  • Clinical Prediction Rule
  • Mortality
  • Hemorrhage, Subarachnoid
  • Model type
    Custom model (Conditional)
    Condition Formula

    Additional information

    The patient characteristics of the 275 consecutive cases of intracranial aneurysm included in this study (Hunt & Hess, 1967) could not be retrieved. All cases were treated at the Ohio State University and affiliated hospitals over a 12-year period. Almost al cases were graded according to the modified Botterell's classification at admission and again just prior to operation.  

    Study Population

    Total population size: 275
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    Females: {{ model.numberOfFemales }}

    Categorical characteristics

    Name Subset / Group Nr. of patients
    Risk grade (modified from Botterell's classification) Grade I 61
    Grade II 88
    Grade III 79
    Grade IV 35
    Grade V 12
    Number of hemorrhages per patients Bled at least once 245
    Bled more than once 116
    Bled two times 73
    Bled three times 35
    Bled four or more times 8
    Hunt and Hess classification of subarachnoid hemorrhage
    Refer to Intended Use for instructions before use
    Evidencio B.V., Irenesingel 19, 7481 GJ, Haaksbergen, the Netherlands

    Related files

    Hunt & Hess risk score:

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    Hunt & Hess risk score: points

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    Outcome stratification

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    Conditional information

    Result interpretation


    Model performance:
    • In a study bij Hunt & Huss (1968) including 275 cases, the mortality was 20% for patients admitted to the hospital at grade I or II, whereas in patients who reached the operating room for any procedure whatever at grade I or II, it was 14%. The difference in mortality was due to a number of instances of early fatal rebleeding. 
    • Worldwide, different scales are used to assess the clinical condition on admission after aneurysmal subarachnoid hemorrhage. In addition to the prognostic value, the inter-rater variability should be taken into account when deciding which scale preferably should be used.
    • In a validation study by Degen et al (2011) including 50 subarachnoid hemorrhage patients, the Hunt and Hess scale showed moderate interobserver agreement (weighted kappa value: 0.48; 95% CI, 0.36–0.59). The World Federation of Neurological Surgeons and the Prognosis on Admission of Aneurysmal Subarachnoid Hemorrhage scales both showed good interobserver agreement (0.64 and 0.60 respectively) with overlapping CI. 

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    Calculations alone should never dictate patient care, and are no substitute for professional judgement. See our full disclaimer.

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