A population-based study of the incidence and case fatality of non-aneurysmal subarachnoid hemorrhage.

BACKGROUND

There is a paucity of reliable and recent data regarding epidemiology of non-aneurysmal subarachnoid hemorrhage (SAH) in population-based studies.

OBJECTIVES

To determine the incidence and case fatality of non-aneurysmal SAH using a population-based design.

METHODS

Medical records and angiographic data of all patients from Stearns and Benton Counties, Minnesota, admitted with SAH were reviewed to identify incident case of non-aneurysmal SAH. Patients with a first-time diagnosis of non-aneurysmal SAH (based on two negative cerebral angiograms performed ≥7 days apart) between June 1st, 2012 and June 30th, 2014 were considered incident cases. We calculated the incidences of non-aneurysmal and aneurysmal SAH adjusted for age and sex based on the 2010 US census.

RESULTS

Of the 18 identified SAH among 189,093 resident populations, five were true incident cases of non-aneurysmal SAH in this population-based study. The age- and sex-adjusted incidence of non-aneurysmal SAH were 2.8 [95 % confidence interval (CI) 2.7-2·9] per 100,000 person-years which was lower than aneurysmal SAH incidence of 7.2 [95 % CI 7.1-7.4] per 100,000 person-years. The age-adjusted incidence of non-aneurysmal SAH was similar (compared with aneurysmal SAH) among men; 3.2 [95 % CI 3.1-3.3] per 100,000 person-years versus 2.2 [95 % CI 2.1-2.3] per 100,000 person-years, respectively. The age-adjusted case fatality rate at 3 months was 4.46 and 0.0 per 100,000 persons for aneurysmal and non-aneurysmal SAH, respectively.

CONCLUSIONS

The incidence of non-aneurysmal SAH was higher than previously reported particularly among men.