Smoking may play causal role in fatal subarachnoid hemorrhage
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Smoking may increase the risk for fatal subarachnoid hemorrhage and potentially affect the familial manifestation of this event, researchers found in an analysis of the Finnish Twin Cohort.
“Our study provides further evidence about the link between smoking and bleeding in the brain,” Ilari Rautalin, BM, 6th-year medical and PhD student at University of Helsinki, said in a press release.
Researchers analyzed data from 16,282 same-sex twin pairs from the Finnish Twin Cohort enrolled from 1976 to 2018. Surveys were conducted at baseline to collect information about hypertension, smoking, BMI, leisure-time physical activity, alcohol use and education. Validated questionnaires were also used to determine whether patients were monozygotic, dizygotic or of unknown zygosity.
Participants were categorized as smokers (occasional and current) or nonsmokers (never and former), in addition to concordant or discordant depending on whether one or both twins died from subarachnoid hemorrhage during follow-up. Researchers obtained follow-up mortality data through a nationwide cause-of-death registry.
There were 120 fatal subarachnoid hemorrhage events during 869,469 person-years of follow-up, of which four cases were in concordant twins and 116 cases were discordant. In the discordant pairs, 25 were considered monozygotic, 72 were dizygotic and 19 were of unknown zygosity.
In the entire cohort, participants who were occasional or current smokers had an increased risk for death from subarachnoid hemorrhage compared with those who never smoked or were former smokers (HR = 3.33; 95% CI, 2.24-4.95).
Researchers also performed pairwise analyses for discordant twin pairs, during which they found that the twin who smoked had a higher risk for fatal subarachnoid hemorrhage compared with the twin that did not smoke (HR = 6.33; 95% CI, 1.87-21.4).
“Our findings suggest that smoking may contribute to the familial manifestation of [subarachnoid hemorrhage] and is consistent with strong evidence for a causal effect,” Rautalin and colleagues wrote. “This finding is in line with the previously reported strong relationship between smoking and this life-threatening stroke type.”
In the press release, Rose Marie Robertson, MD, FAHA, deputy chief science and medical officer for the American Heart Association and co-director of the AHA Tobacco Center for Regulatory Science, said: “This long-term study in twins helps to confirm the link between subarachnoid hemorrhage and smoking. Not smoking, or quitting if you've already started, is an essential component of primary prevention.”
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