Smoking and Stroke – A Critical Connection on World No Tobacco Day 2024

Today, on World No Tobacco Day 2024 initiated by the WHO, we want to highlight the critical connection between smoking and stroke, two significant public health concerns.

Cigarette smoking is a well-established risk factor for all forms of stroke being clearly identified as one of the main preventable risk factors for cerebrovascular events. According to the Centers for Disease Control and Prevention, 47.1 million US adults reported using any form of commercial tobacco/nicotine products. In 2021, 28.3 million U.S adults reported smoking cigarettes, 7% of total cerebrovascular disease deaths worldwide being linked to tobacco smoking^1–3.

Tobacco smoking contributes to an increased risk of stroke through various mechanisms including carboxyhemoglobinemia, prothrombotic effect, vasomotor dysfunction, inflammation, modification of lipid profile and direct toxic effects of vapour compounds, both primary and environmental tobacco smoke exposure being linked to atherosclerosis and arterial damage⁴.

Atherosclerosis predisposes individuals to small-vessel disease, mainly caused by endothelial dysfunction, inflammation, impaired endogenous fibrinolysis and reduced blood flow caused by secondary vasoconstriction, all this contributing to lacunar strokes and white matter lesions.

In the Interstroke study, the authors have evaluated tobacco use and the risk of acute stroke in 32 countries. Current smoking was highly associated with an increased risk of all stroke types (odds ratio 1.64, 95% CI 1.46–1.84) having a stronger association with ischemic stroke when compared with intracerebral hemorrhage (ICH) (OR 1.85, 95% CI 1.61–2.11 vs. OR 1.19 95% CI1.00–1.41). In the same study, the authors have concluded that the strongest association of current smoking was seen with large vessel stroke subtype and undetermined cause. Regarding the environmental exposure to tobacco, all the studies have shown that the risk of stroke is dose-dependent, exposure for more than 10h/week increased the risk of all types of stroke ⁵. In a meta-analysis published in 2019 by Pan et al. there is a strong dose-dependent relationship between smoking and the risk of ischemic stroke, with 12% higher chances of an acute cerebrovascular event with every increment of 5 cigarettes per day ⁶

Ischemic stroke is not the only type of stroke associated with tobacco usage, an increased risk was also observed for ICH and subarachnoid hemorrhage (SAH). Kurth et al. observed that the risk of ICH and SAH in females smoking more than 15 cigarettes per day respectively in males smoking more than 20 cigarettes per day is significantly higher when compared with non-smokers ^7,8.

Several studies have shown that smoking cessation decreases the risk of stroke for former smokers when compared with current smokers by 34%. Former smokers who have maintained smoking cessation for more than 5 years presented an almost identical risk of stroke as that of lifetime non-smokers ⁹.  In a meta-analysis, the implementation of smoke-free legislation has reduced the number of admissions for cardiovascular events by 16%, lowering the mortality and morbidity secondary to cerebrovascular events s (RR 0.84, 95% CI 0.75–0.93) ¹⁰.

World No Tobacco Day serves as a crucial platform to educate and advocate for tobacco cessation. By raising awareness about the link between smoking and stroke, we can encourage individuals and communities to take proactive steps towards a smoke-free life, ultimately reducing the incidence of stroke and improving overall public health.

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References:

1. Geneva: World Health Organization. WHO report on the global tobacco epidemic 2021: addressing new and emerging products.
2. Feigin VL, Roth GA, Naghavi M, et al. Global burden of stroke and risk factors in 188 countries, during 1990-2013: a systematic analysis for the Global Burden of Disease Study 2013. Lancet Neurol 2016; 15: 913–924.
3. Cornelius ME, Loretan CG, Wang TW, et al. Tobacco Product Use Among Adults — United States, 2020. MMWR Morb Mortal Wkly Rep 2022; 71: 397–405.
4. Ambrose JA, Barua RS. The pathophysiology of cigarette smoking and cardiovascular disease: An update. J Am Coll Cardiol 2004; 43: 1731–1737.
5. Wang X, Liu X, O’Donnell MJ, et al. Tobacco use and risk of acute stroke in 32 countries in the INTERSTROKE study: a case–control study. EClinicalMedicine; 70. Epub ahead of print 1 April 2024. DOI: 10.1016/j.eclinm.2024.102515.
6. Pan B, Jin X, Jun L, et al. The relationship between smoking and stroke: A meta-analysis. Medicine; 98. Epub ahead of print 2019. DOI: 10.1097/MD.0000000000014872.
7. Kurth T, Kase CS, Berger K, et al. Smoking and the risk of hemorrhagic stroke in men. Stroke 2003; 34: 1151–1155.
8. Kurth T, Kase CS, Berger K, et al. Smoking and risk of hemorrhagic stroke in women. Stroke 2003; 34: 2792–2795.
9. Wolf PA, D’agostino RB, Kannel WB, et al. Cigarette smoking as a risk factor for stroke. The Framingham Study. JAMA 1988; 259: 1025–1029.
10. Tan CE, Glantz SA. Association between smoke-free legislation and hospitalizations for cardiac, cerebrovascular, and respiratory diseases: A meta-analysis. Circulation 2012; 126: 2177–2183.