====== Aneurysmal subarachnoid hemorrhage epidemiology ======

[[Aneurysmal subarachnoid hemorrhage]] (aSAH) accounts for only 3-5% of all [[stroke]]s.

Estimated annual rate of aneurysmal [[subarachnoid hemorrhage]] in most western populations: 6-9 per 100,000 population per year
((Dehdashti AR, Rilliet B, Rufenacht DA, de Tribolet N: Shunt-dependent hydrocephalus after rupture of intracranial aneurysms: a prospective study of the in uence of treatment modality. J Neurosurg 101:402–407, 2004))
((Zacharia BE, Hickman ZL, Grobelny BT, DeRosa P, Kotch- etkov I, Ducruet AF, et al: Epidemiology of aneurysmal sub- arachnoid hemorrhage. Neurosurg Clin N Am 21:221–233, 2010)).

===== Gender =====
Aneurysmal subarachnoid hemorrhage (aSAH) is more common in women than in men.

Women outnumbered men among aSAH patients, especially along increasing age strata, and had increased global disease severity on admission. No other significant differences between genders were found
((De Marchis GM, Schaad C, Fung C, Beck J, Gralla J, Takala J, Jakob SM.
Gender-related differences in aneurysmal subarachnoid hemorrhage: A hospital
based study. Clin Neurol Neurosurg. 2017 Apr 6;157:82-87. doi:
10.1016/j.clineuro.2017.04.009. [Epub ahead of print] PubMed PMID: 28456071.
)).


===== China =====
The age and gender information of 4,895 cases of aneurysmal SAH (3,016 females, 1,879 males) were collected retrospectively from eight institutions in mainland [[China]]. The [[prevalence]] of aneurysmal SAH of men and women at different ages was analyzed.

The data showed women had a higher incidence of aneurysmal SAH than men starting at late thirties, and men might have a higher incidence of aneurysmal SAH than women only before 37-year-old.

Menopause may not be the only dominant factor causing higher incidence of aneurysmal SAH in women than in men
((Wáng YX, He J, Zhang L, Li Y, Zhao L, Liu H, Yang L, Zeng XJ, Yang J, Peng GM,
Ahuja A, Yang ZH. A higher aneurysmal subarachnoid hemorrhage incidence in women 
prior to menopause: a retrospective analysis of 4,895 cases from eight hospitals 
in China. Quant Imaging Med Surg. 2016 Apr;6(2):151-156. PubMed PMID: 27190767.)).

===== South Korea =====
Trends in the [[incidence]]s of newly detected [[unruptured aneurysm]]s (UA) and [[SAH]] and trends in the treatment modalities used were assessed from 2005 to 2015 using the nationwide database of the Korean National Health Insurance Service in [[South Korea]]. They also evaluated the influence of demographic characteristics including socioeconomic factors on the incidence and treatment of UA and SAH.

The marked increase in the detection and treatment of UA might have contributed to the decreasing incidence of SAH, though levels of contribution depend on socioeconomic status despite universal medical insurance coverage
((Lee WK, Oh CW, Lee H, Lee KS, Park H. Factors influencing the incidence and
treatment of intracranial aneurysm and subarachnoid hemorrhage: time trends and
socioeconomic disparities under an universal healthcare system. J Neurointerv
Surg. 2018 Jun 22. pii: neurintsurg-2018-013799. doi:
10.1136/neurintsurg-2018-013799. [Epub ahead of print] PubMed PMID: 29934441.
)).
===== United States =====

In the United States alone, there are up to 30,000 new cases of aSAH per year
((Zacharia BE, Hickman ZL, Grobelny BT, DeRosa P, Kotchetkov I, Ducruet AF, et al: Epidemiology of aneurysmal subarachnoid hemorrhage. Neurosurg Clin N Am 21:221–233, 2010)).

Only 8 studies have investigated the [[Aneurysmal subarachnoid hemorrhage epidemiology]] in the [[United States]]. 
In the first investigation in [[Indiana]], which has some of the highest rates of [[tobacco]] [[smoking]] and [[obesity]] in the nation. Ziemba-Davis et al. prospectively identified 441 consecutive patients with aSAH from 2005 to 2010 at 2 [[hospital]]s where the majority of cases are treated. [[Incidence]] calculations were based on US Census populations. Epidemiologic variables included [[demography]]; [[risk factor]]s; Hunt and Hess scale; Fisher grade; number, location, and size of aneurysms; treatment type; and complications. The overall incidence was 21.8 per 100,000 population. Incidence was higher in women, increased with age, and did not vary by race. One third to half of the patients were hypertensive and/or smoked cigarettes at the time of [[ictus]]. Variations by count were partially explained by Health Factor and Morbidity Rankings. Complications varied by treatment. These findings deviate from estimates that 6-16 per 100,000 people in the United States will develop aSAH and are double the incidence in a [[Minnesota]] population between 1945 and 1974. The results also deviate from the worldwide estimate of 9.0 aSAHs per 100,000 person-years. The predictive value of variations in Health Factor and Morbidity Rankings implicates the importance of future research on multivariate biopsychosocial causation of aSAH
((Ziemba-Davis M, Bohnstedt BN, Payner TD, Leipzig TJ, Palmer E, Cohen-Gadol AA.
Incidence, epidemiology, and treatment of aneurysmal subarachnoid hemorrhage in
12 midwest communities. J Stroke Cerebrovasc Dis. 2014 May-Jun;23(5):1073-82.
doi: 10.1016/j.jstrokecerebrovasdis.2013.09.010. Epub 2013 Oct 19. PubMed PMID:
24144595.
)).