One of the most devastating cerebrovascular catastrophes causing death in 40 to 50% of the cases is subarachnoid haemorrhage (SAH). The most common cause of SAH is a rupture of an intracranial aneurysm. If the aneurysm is found, it can be treated before the possible rupture. However, some intracranial aneurysms will never rupture - the problem is that the doctors don't know which aneurysms will and which will not. So, they don't know which patients should be treated and who can safely be left untreated.
A long-term, population-based Finnish study on SAH, which is based on the FINRISK health examination surveys, and published in PLOS ONE
on 9th September, shows that the risk of SAH depends strongly on the combination of certain risk factors. The SAH incidence was shown to vary from 8 up to 171 per 100 000 person-years, depending on whether people had multiple risk factors for SAH - such as smoking, hypertension and female sex - or not.
Such an extreme risk factor -dependent variation in the incidence of any cardiovascular disease is exceptional, and may have significant clinical implications, says one of the main authors, Associate Professor Miikka Korja from the Helsinki University Central Hospital and Australian School of Advanced Medicine.
If smoking women with high systolic blood pressure values have 20 times higher rate of these brain bleeds than never-smoking men with low blood pressure values, it may very well be that these women diagnosed with unruptured intracranial aneurysms should be treated. On the other hand, never-smoking men with low blood pressure values and intracranial aneurysms may not need to be treated at all.