Source: UCL Cancer Institute, University College London / BMJ
Summary: A review of the evidence concluded that smoking just one cigarette a day has a much higher risk of developing coronary heart disease and stroke than expected – about half the risk of smoking 20 per day.
Around 1 billion adults smoke worldwide, with high prevalence in developing countries, where 49% of men and 11% of women use tobacco. However the prevalence of current smokers has decreased over time but owing to population growth, the global absolute number of smokers has increased. People were successfully encouraged to quit smoking by using alternate aids such as nicotine replacement therapy and electronic cigarettes. Smoking few cigarettes is generally believed to be relatively safe or little harm but researchers from UCL Cancer Institute have found that smoking just one cigarette a day has a much higher risk of developing coronary heart disease and stroke than expected, about half the risk of smoking 20 per day. The study findings were published in the British Medical Journal.
The meta-analysis included 55 publications containing 141 cohort studies. Researchers found that men who smoked one cigarette per day had 46% of the excess risk of heart disease and 41% of the excess risk of stroke associated with smoking 20 cigarettes per day (much higher than the expected 5%). For women, those who smoked one cigarette per day had 31% of the excess risk of heart disease and 34% of the excess risk of stroke associated with smoking 20 cigarettes per day. They argue that smokers should stop completely instead of cutting down to significantly reduce their risk of heart disease and stroke. This study is a valuable reference that can be used to strengthen public health campaigns, and provide a strong health incentive for smokers to stop completely (particularly women).
The authors conclude: “No safe level of smoking exists for cardiovascular disease. Smokers should quit instead of cutting down, using appropriate cessation aids if needed, to significantly reduce their risk of these two common major disorders.”
More Information: Allan Hackshaw et al, “Low cigarette consumption and risk of coronary heart disease and stroke: meta-analysis of 141 cohort studies in 55 study reports”, British Medical Journal (2018). www.bmj.com/content/360/bmj.j5855