Can one cigarette a day cause cardiovascular disease? To answer this question, Hackshaw, et al (2018), conducted a meta-analysis of well-powered, prospective cohort studies that reported relative risks (using regression analysis) of persons who smoked 1, 5, 10 or 20 cigarettes per day, compared with never smokers in terms of age specific incidence of coronary heart disease or stroke. The results were surprising. After adjusting for age and additional confounding variables, a relative risk factor could be established between the number of cigarettes smoked per day and the risk for coronary disease and stroke.
Smoking and Heart Disease
Among men, after adjusting for confounding variables, the relative risk for coronary heart disease was 1.74 for those who smoked one cigarette per day and 2.27 among those who smoked 20 cigarettes per day.
Among women, the relative risk for coronary heart disease was 2.19 for those who smoked one cigarette per day and 3.95 among those who smoked 20 cigarettes per day.
Smoking and Stroke
For men, after adjusting for multiple variables, the relative risks were 1.30 and 1.56 for smoking one versus 20 cigarettes per day.
For women, after adjusting for multiple variables, the relative risks were 1.46 and 2.42 for smoking one versus 20 cigarettes per day. Relative risks are generally for women than for men.
Clearly, no safe level of smoking exists for cardiovascular disease.
The CDC (2016) reports that 37.8 million adults in the United States currently smoke cigarettes and more than 16 million Americans currently have a smoking-related disease.
Forty-six million adults in the U.S. used both alcohol and tobacco in the past year, and approximately 6.2 million adults reported both an alcohol use disorder and smoking addiction. In 2004, Williams and Ziedonis found that between 50 to 90% of people with a mental illness or substance use disorder were also addicted smokers.
Smokers should be educated on these data by their health provider and advised and helped to quit because their life expectancy is at stake instead of attempting to simply cut down their use.
Hackshaw A, Morris JK, Boniface S, Tang JL, Milenković D.
Low cigarette consumption and risk of coronary heart disease and stroke: meta-analysis of 141 cohort studies in 55 study reports. BMJ. 2018 Jan 24;360:j5855. doi: 10.1136/bmj.j5855.