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The frequency of Subarahhnoid haemorrhage in Mannheim has significantly decreased since the 1960s, indicating a meta-analysis. JAMA Neurology (2019; doi: 10.1001 / jamaneurol.2019.0006) to improve blood pressure control and reduce the number of smokers. One exception is Japan, where subarachnoid bleeding increases.
Most subarachnoid bleeding, which accounts for about 5% of all strokes, is caused by a rupture of the aneurysm at the base of the skull. Aneurysms are usually hereditary. They grow up in their lifetime until they "burst", that is, if half of those who suffered before the age of 55.
The cause of aneurysms is genetic, but their growth is influenced by external factors. This explains why the number of subarahhnoid haemorrhages has changed over time (faster than possible gene pool). The team, led by Nima Etminan from the University Medical Center in Mannheim, has evaluated 75 studies that reflect developments in 32 (richer) countries.
In most countries, the number of subarachnoid bleeding has decreased. In Europe, it fell by 40.6% between 1980 and 2010, by 46.2% in Asia and by 14.0% in North America. However, in Japan the frequency increased by 59.1%. 100,000 people arrived in 2006 27.9 Subarachnoidalblutungen. In Germany the same year there were 5.1 subarachnoid bleeding per 100,000 people. The reason for the increase cannot be explained in the study. However, according to Etmin, there is still a large number of smokers: 26.1% in Japan, compared with 19.3% worldwide.
Smoking is considered to be a significant risk factor to increase aneurysm size before it ruptures because smoking damages the walls of the blood vessels and accelerates atherosclerosis. The Etminan analysis confirms this: any decrease in 1% smoking prevalence was associated with a 2.4% reduction in subarachnoid haemorrhage (95% confidence interval from 1.6 to 3.3).
The second major risk factor is high blood pressure. Again, the figures show a clear relationship: with 1 mmHg of systolic blood pressure, the frequency of subarachnoid bleeding decreased by 7.1% (5.8-8.4%). Diastolic blood pressure of 1 mmHg was less associated with a decrease of 11.5% (8.8-14.3).
The prevalence of arterial hypertension has decreased (according to the results of other studies) in many western countries as more and more people control their blood pressure with antihypertensive drugs or prevent their development using statins.
Strictly speaking, the study cannot prove that better blood pressure control and smoking prevention are responsible for a reduction in subarachnoid bleeding. However, the results are an important indicator of Etminan. The expert refers to the ongoing PROTECT-U study, which randomized 776 patients with CT (usually random) to treat aneurysm with acetylsalicylic acid or intense blood pressure control. The end point of the study is the rate or rupture of aneurysm growth. The results could be available in October 2022.
The guidelines recommend ablation or surgical removal that exceeds the size of certain aneurysms. The number of these prophylactic therapies has increased in recent years. However, they have been too rarely made to explain the reduction in subarachnoid haemorrhage that has already occurred in the period when the diagnosis and treatment of aneurysms was still very rare. © warmth / aerzteblatt.de