The increased risk of stroke that comes with smoking may extend to nonsmokers who live in the same household and breathe in secondhand smoke, a U.S. study suggests.
Researchers found that never-smokers who had a stroke were nearly 50 percent more likely to be exposed to secondhand smoke at home than people who had never had a stroke.
During the study, stroke survivors exposed to secondhand smoke were also more likely to die from any cause compared to those without secondhand smoke exposure.
One in four nonsmokers (58 million people) in the U.S. are still exposed to secondhand smoke, according to the Centers for Disease Control and Prevention.
“While cigarette smoking has long been known to increase the risk of stroke, less is known about the relationship between secondhand smoke and stroke,” Lin said by email.
The researchers also looked at other factors that might influence stroke risk or likelihood of secondhand smoke exposure like race, sex, education and income level.
The people most likely to be exposed to secondhand smoke at home were black men with high alcohol intake and a history of heart attack who were living in poverty.
Among survey participants between 1999 and 2012, people exposed to high amounts of secondhand smoke, as measured by blood cotinine, were 46 percent more likely than those exposed to little or no smoke to have a history of past stroke.
In the 1988-1994 group, the results were different, and secondhand smoke exposure wasn’t linked to increased stroke risk. The study team writes in the journal Stroke that this difference requires further investigation.
Among all participants, however, stroke survivors who reported secondhand smoke exposure were about twice as likely to die of any cause, compared with stroke survivors not exposed to smoke.
This added risk of death among people with prior stroke increased along with the amount of smoke exposure.