SoylentNews

martyb writes:

Smokers and Hypertensive Individuals have Higher Risk of Sudden Death from Brain Bleed:

Contrary to the previous data, a Finnish study clarifies that smoking and high blood pressure do not protect from death in patients suffering from subarachnoid haemorrhage, the most lethal stroke subtype. In fact, subarachnoid haemorrhage kills smokers and hypertensive individuals already before they reach hospitals, and therefore studies that cannot include these outside hospitals deaths in analyses may reach erroneous conclusions.

Subarachnoid haemorrhage is a severe stroke subtype that is caused by a rupture of a brain aneurysm, an enlargement in the brain vessel wall. Up to one in four subarachnoid haemorrhage patients die quickly after the bleed at home, on the road to a hospital, or in an emergency room. These patients never reach hospital wards and are often incorrectly diagnosed. In many countries, these sudden deaths are classified as sudden cardiac deaths since routine autopsies are rarely conducted outside Nordic countries.

If only patients who survive the initial bleed and reach hospital wards are included in studies on risk factors of subarachnoid haemorrhage, such studies are very likely biased, because they are unable to study risk factors relating to the most devastating outcome, namely sudden death.

Two recent hospital-based studies, that excluded patients who died before reaching hospital wards, reported that smokers and hypertensive individuals have better chances to survive from subarachnoid haemorrhage than non-smokers and those with normal blood pressures.

These findings puzzled researchers and clinicians because they contradicted earlier reports. For decades, the researchers and clinicians have known that smoking and high blood pressure are the two most important risk factors for subarachnoid haemorrhage, but now the studies suggest that the same factors would paradoxically protect from subarachnoid haemorrhage-related death.

A study, published in the distinguished Neurology journal, shows that when researches[sic] are able to include those people who die before reaching hospital wards, the paradoxical protective effect of smoking and high blood pressure is reversed. Specifically, the study showed that smokers and hypertensive individuals die more frequently before they reach hospital wards than non-smokers and those with normal blood pressure. When these heavy smokers and hypertensive people are left out from statistical analyses, the results are misleading.

Journal Reference:
Joni V. Lindbohm, Jaakko Kaprio, Miikka Korja. Survival bias explains improved survival in smokers and hypertensive individuals after aSAH^$. Neurology, 2019; 10.1212/WNL.0000000000008537 DOI: 10.1212/WNL.0000000000008537

Original Submission