ORIGINAL ARTICLE - VASCULAR
Regional differences in the incidence of aneurysmal
subarachnoid haemorrhage in Finland
Received: 24 January 2017 /Accepted: 7 June 2017 /Published online: 11 July 2017
Springer-Verlag GmbH Austria 2017
Background Over the years, the consensus has generally been
that Finland is a country with a significantly high incidence of
aneurysmal subarachnoid haemorrhage (SAH) when compared
to the rest of the world, excluding Japan. Most of the tradition-
ally cited Finnish incidence studies are several decades old and
have clear differences in their methodology and study design.
The objective of this study was to determine the hospital-
admitted incidence of aneurysmal SAH at Tampere
University Hospital between 1990 and 2014. We also com-
pared the incidence to other geographical regions in Finland.
Methods The material for this study consists of patients ad-
mitted to Tampere University Hospital between 1990 and
2014 with the presentation of aneurysmal SAH. There was a
total of 1965 patients with aneurysmal SAH in our data.
Results The mean hospital-admitted aneurysmal SAH inci-
dence over the period was 7.41 per 100,000 person-years.
The hospital-admitted aneurysmal SAH incidence in the
Eastern Finland region was two-thirds greater than in the
Tampere University Hospital region.
Conclusions We observed a relatively steady hospital-
admitted incidence of aneurysmal SAH (7.41 per 100,000
person-years) in the Tampere University Hospital region.
This result is parallel to a recent study looking into the inci-
dence of aneurysmal SAH for the whole of Finland.
Compared to the Tampere University Hospital region, the in-
cidence was 64% greater in the Eastern Finland region.
Aneurysmal subarachnoid haemorrhage (SAH) is caused by
the rupture of an intracranial aneurysm. It has a high case
mortality and morbidity, and the peak incidence affects the
working age population, causing high socio-economical
losses to the community [2, 9, 12, 25].
Generally the incidence of aneurysmal SAH has been report-
ed to be around 8–12 cases per 100,000 person-years [5, 30, 31,
33]—overall about 9 per 100,000 person-years —with the
exception of Finland and Japan, were the incidence figures have
been much higher, as high as 19–30 cases per 100,000 person
years [7, 13, 21, 22, 28]. The two commonly cited Finnish stud-
ies by Sarti et al.  and Fogelholm  are somewhat dated,
being published in 1991 and 1981, respectively.
A recent register-based Finnish study showed a significant
trend of decreased total incidence of aneurysmal SAH in
Finland over the 1998–2012 period, matching the European stan-
dard population incidence of 8.9 per 100,000 person-years be-
tween2010and2012. Most aneurysmal SAH incidence
studies in Finland are based on geographically small areas and
are extrapolated to cover the national population [7, 28].
It has previously been observed that the incidence of
cardiovascular diseases varies significantly in the different
regions of Finland [17, 23, 27]. There have been signs of
differences in arterial wall thickness and the workings of
arterial intima between subjects from Eastern Finland and
those from Western Finland . In the patient material of
rysmal SAH incidence similar to the difference in cardio-
vascular disease incidence. It has also previously been
* Iiro Jalava
University of Tampere, Pellervonkatu 23 A 33,
33540 Tampere, Finland
Acta Neurochir (2017) 159:1657–1662