What is the clinical evidence from this study?

Study design: Observational. Population: Subarachnoid hemorrhage (n=433). Intervention: Time period (2010) vs. Time period (1988). Primary outcome: 30-day case-fatality rate (p=0.001).

October 22, 2016Neurology129 citations

Stable incidence but declining case-fatality rates of subarachnoid hemorrhage in a population

JMJason Mackey JKJane Khoury KAKathleen Alwell

Key Result

From 1988 to 2010, 30-day case-fatality rates for subarachnoid hemorrhage declined significantly from 46% to 25%, despite stable incidence rates.

Study Design

Type

Observational (n=433)

Multicenter

Yes

Structured PICO

Population

433 adults aged 20 and older with incident nontraumatic subarachnoid hemorrhage in the Greater Cincinnati/Northern Kentucky region across 5 time periods between 1988 and 2010.

Outcome

Incidence of SAH and all-cause case-fatality rates at 5, 30, and 90 days after initial SAHhard clinical

Population-based data from 1988 to 2010 demonstrate that while the incidence of subarachnoid hemorrhage has remained stable, short-term case-fatality rates have significantly declined, likely reflecting advances in medical and surgical management.

Main Result

Absolute Event Rate: 25% vs 46%

p-value: p=0.001

Limitations

Retrospective and descriptive observational design cannot establish causality for declining case-fatality rates.
Missing data from the 1988 cohort, including severity scores and baseline functional status.
Lack of consistent formal grading of SAH severity across time periods.
No data collected on aggressiveness of care or withdrawal of care.
Potential detection bias for smaller SAHs due to increasing use of sophisticated diagnostic imaging.
Inability to determine SAH etiology with certainty in a substantial portion of cases, especially in 1988.

Abstract

OBJECTIVE: To characterize temporal trends in subarachnoid hemorrhage (SAH) incidence and outcomes over 5 time periods in a large population-based stroke study in the United States. METHODS: All SAHs among residents of the Greater Cincinnati/Northern Kentucky region at least 20 years of age were identified and verified via study physician review in 5 distinct year-long study periods between 1988 and 2010. We abstracted demographics, care patterns, and outcomes, and we compared incidence and case-fatality rates across the study periods. RESULTS: The incidence of SAH in the 5 study periods (age-, race-, and sex-adjusted to the 2000 US population) was 8.8 (95% confidence interval 6.8-10.7), 9.2 (7.2-11.2), 10.0 (8.0-12.0), 9.0 (7.1-10.9), and 7.7 (6.0-9.4) per 100,000, respectively; the trend in incidence rates from 1988 to 2010 was not statistically significant (p = 0.22). Advanced neurovascular imaging, endovascular coiling, and neurologic intensive care unit availability increased significantly over time. All-cause 5-day (32%-18%, p = 0.01; for trend), 30-day (46%-25%, p = 0.001), and 90-day (49%-29%, p = 0.001) case-fatality rates declined from 1988 to 2010. When we included only proven or highly likely aneurysmal SAH, the declines in case-fatality were no longer statistically significant. CONCLUSIONS: Although the incidence of SAH remained stable in this population-based region, 5-day, 30-day, and 90-day case-fatality rates declined significantly. Advances in surgical and medical management, along with systems-based changes such as the emergence of neurocritical care units, are potential explanations for the reduced case-fatality.

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