Trends in Hospitalization and Mortality for Subarachnoid Hemorrhage and Unruptured Aneurysms in the United States

Objective: During the past decade, endovascular obliteration of intracranial aneurysms and new treatments for vasospasm and cerebral ischemia have been introduced. To analyze the effectiveness of these new strategies, we evaluated changes in morbidity and mortality rates in patients at least 18 years of age who were hospitalized for ruptured and unruptured intracranial aneurysms during the past 16 years.

Methods: National estimates of hospitalization for subarachnoid hemorrhage (SAH) and unruptured intracranial aneurysms and associated in-hospital outcomes and mortality were obtained from National Hospital Discharge Survey data. All the variables pertaining to hospitalization were compared for three distinct time periods: 1986-1990, 1991-1995, and 1996-2001.

Results: There were 94,692, 104,746, and 133,269 admissions for SAH during the periods 1986-1990, 1991-1995, and 1996-2001, respectively. Mortality rates for hospitalizations related to SAH demonstrated no significant change in mortality during the periods 1986-1990, 1991-1995, and 1996-2001 (27.6%, 24.6%, and 26.3%, respectively. Procedures performed for SAH from 1996 to 2001 included surgical clipping (28%), endovascular/wrapping (2%), and no procedure (70%). The number of admissions for unruptured intracranial aneurysms was 23,481 from 1986 to 1990, 28,017 from 1991 to 1995, and 51,904 from 1996 to 2001. There was an overall trend (P = 0.07) toward reduced in-hospital mortality during the three periods: 5.9%, 6.3%, and 1.4% for 1986-1990, 1991-1995, and 1996-2001, respectively.

Conclusion: The mortality rate for unruptured intracranial aneurysms demonstrates a significant trend of reduction during the past 16 years. The mortality rate for SAH demonstrates limited change during the same period; it is presumed that this is attributable to the multitude of factors that influence outcome.