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Original research
Mapping geographic disparities in treatment and clinical outcomes of high-grade aneurysmal subarachnoid hemorrhage in the United States


Background and objective Although high-grade (Hunt and Hess 4 and 5) aneurysmal subarachnoid hemorrhage (aSAH) typically portends a poor prognosis, early and aggressive treatment has previously been demonstrated to confer a significant survival advantage. This study aims to evaluate geographic, demographic, and socioeconomic determinants of high-grade aSAH treatment in the United States.

Methods The National Inpatient Sample (NIS) was queried to identify adult high-grade aSAH hospitalizations during the period of 2015 to 2019 using the International Classification of Diseases, 10th Revision, Clinical Modification (ICD) codes. The primary clinical endpoint of this analysis was aneurysm treatment by surgical or endovascular intervention (SEI), while the exposure of interest was geographic region by census division. Favorable functional outcome (assessed by the dichotomous NIS-SAH Outcome Measure, or NIS-SOM) and in-hospital mortality were evaluated as secondary endpoints in treated and conservatively managed groups.

Results Among 99 460 aSAH patients identified, 36 795 (37.0%) were high-grade, and 9210 (25.0%) of these were treated by SEI. Following multivariable logistic regression analysis, determinants of treatment by SEI included female sex (adjusted OR (aOR) 1.42, 95% CI 1.35 to 1.51), transfer admission (aOR 1.18, 95% CI 1.12 to 1.25), private insurance (ref: government-sponsored insurance) (aOR 1.21, 95% CI 1.14 to 1.28), and government hospital ownership (ref: private ownership) (aOR 1.17, 95% CI 1.09 to 1.25), while increasing age (by decade) (aOR 0.93, 95% CI 0.91 to 0.95), increasing mortality risk (aOR 0.60, 95% CI 0.57 to 0.63), urban non-teaching hospital status (aOR 0.66, 95% CI 0.59 to 0.73), rural hospital location (aOR 0.13, 95% CI 0.7 to 0.25), small hospital bedsize (aOR 0.68, 95% CI 0.60 to 0.76), and geographic region (South Atlantic (aOR 0.72, 95% CI 0.63 to 0.83), East South Central (aOR 0.75, 95% CI 0.64 to 0.88), and Mountain (aOR 0.72, 95% CI 0.61 to 0.85)) were associated with a lower likelihood of treatment. High-grade aSAH patients treated by SEI experienced significantly greater rates of favorable functional outcomes (20.1% vs 17.3%; OR 1.20, 95% CI 1.13 to 1.28, P<0.001) and lower rates of mortality (25.8% vs 49.1%; OR 0.36, 95% CI 0.34 to 0.38, P<0.001) in comparison to those conservatively managed.

Conclusion A complex interplay of demographic, socioeconomic, and geographic factors influence treatment patterns of high-grade aSAH in the United States.

  • Aneurysm
  • Hemorrhage
  • Subarachnoid

Data availability statement

The data used in this analysis as well as a comprehensive list of billing codes used to define the clinical variables in this study (other than those explicitly denoted in the body of the methods section of this manuscript) are available upon reasonable request of the corresponding author following completion of onboarding and verification procedures as specified by the Healthcare Cost and Utilization Project (HCUP).

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