HealthDay News — Smoking 1 cigarette per day is still associated with a significant increased risk of coronary heart disease and stroke, according to research published online in The BMJ.

Allan Hackshaw, PhD, from Cancer Research UK in London, and colleagues quantified the risk of coronary heart disease and stroke associated with light smoking. The relative risks were pooled in a meta-analysis; 55 publications with 141 cohort studies were included in the meta-analysis.

The researchers found that the pooled relative risk for coronary heart disease was 1.48 and 2.04, respectively, for smoking one and 20 cigarettes per day for men, using all studies, and 1.74 and 2.27, respectively, in studies in which the relative risk [RR] was adjusted for multiple confounding variables. 

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For women, the corresponding RR were 1.57 and 2.84 for one and 20 cigarettes per day, and 2.19 and 3.95, respectively, after multivariable adjustment. Men and women who smoked 1 cigarette per day had 46% and 31%, respectively, of the excess RR of smoking 20 cigarettes per day (53% and 38%, respectively, using RR adjusted for multiple variables). For stroke, the excess risk associated with one versus 20 cigarettes per day was 41% and 34% for men and women, respectively (64% and 36%, respectively, using relative risks adjusted for multiple variables).

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“Smoking only about 1 cigarette per day carries a risk of developing coronary heart disease and stroke much greater than expected,” the authors write.


Hackshaw A, Morris JK, Boniface S, Tang JL, Milenković D. Low cigarette consumption and risk of cornary heart disease and stroke: meta-analysis of 141 cohort studies in 55 study reports. BMJ. 2018;360:j5855.