  Purpose: Rupture of an intracranial aneurysm is the most common cause of
subarachnoid haemorrhage (SAH), which is a life-threatening acute
cerebrovascular event that typically affects working-age people. This study
aims to investigate the aneurysmal SAH incidence rate in elderly population
than in middle aged population in China. Materials and methods: Aneurysmal SAH
cases were collected retrospectively from the archives of 21 hospitals in
Mainland China. All the cases collected were from September 2016 and backward
consecutively for a period of time up to 8 years. SAH was initially diagnosed
by brain computed tomography, and CT angiography (CTA) or digital subtraction
angiography (DSA) was followed and SAH was confirmed to be due to cerebral
aneurysm. When for cases multiple bleeding occurred, the age of the first SAH
was used in this study. The toltal incidence from all hospital at each age were
summed together for females and males; then adjusted by the total population
number at each age for females and males. The total population data was from
the 2010 population census of the People's Republic of China. Results: In total
there were 8,144 cases, with 4,861 females and 3,283 males. Our analysis shows
for both females and males the relative aneurysmal SAH rate started to decrease
after around 65 years old. The males the relative aneurysmal SAH rate might
have started to decrease after around 55 years old. Conclusion: In contrast to
previous reports, our data demonstrated a decreased aneurysmal subarachnoid
hemorrhage incidence rate in elderly population than in middle aged population.
Our data therefore support the hypothesis that aneurysms do not grow
progressively once they form but probably either rupture or stabilize and that
very elderly patients are at a reduced risk of rupture compared with atients
who are younger with the same-sized aneurysms.
