Tobacco Documents Online

Smoking and heart disease. The missing link. Does smoking cause heart disease? If we asked 100 people that question it is a pretty safe bet that a majority would answer 'yes' without much hesitation. After all, most people are aware of research studies that report a statistical correlation between smoking and heart disease. And [illegible text] there, it's easy to jump to the "logical" conclusion that smoking must cause the disease. But scientists know better. Because scientists know that the chains which connects a cause to an effect must be made from solid proof. And of all the links in such a chain, statistics are the weakest. Statistics Are Not proof. First of all, statistics simply cannot prove cause and effect. This is a principle that is accepted by virtually every scientists today. Second, heart disease is statistically correlated not just with smoking but also with many other risk factors, including stress, aging, cholesterol levels, hypertension and aging. Which of these factors if any, is casually related to heart disease has yet to be determined. And most important, there are many statistical studies which contradict the findings that supposedly associate heart disease with smoking. You may not be aware of these studies, since they usually get little coverage in the media. And you may be suspicious that they are being brought to your attention by a tobacco company. But a no less independent authority than the American Heart Journal reviewed the scientific literature on the issue in 1980 and wrote in an editorial: (T)here is not established proof that cigarette smoking is causally related to coronary heart disease. More Recent Findings. "Perhaps," the skeptics might reply. "But that 1980 editorial is ancient history. A lot could have happened since then." Indeed, a good deal has been published on the subject on the subject since 1980. But much of the material casts even greater doubt on the theory that smoking causes heart disease. One example: in 1982, results were published from a federal government study involving 120,000 men who were thought to have a high risk of heart disease because of three factors---smoking habits, high blood pressure, and high cholesterol levels. But after 10 years and $115 million, this Multiple Risk Factor Intervention Trial (MRFIT) showed that reducing those factors did not reduce the risk of heart disease. In another study, researchers who followed 2,800 American women over 20 years reported in 1981 that those who smoked ran no greater risk of getting coronary disease or stroke than those who did not smoke. Nor have experiments in the laboratory been able to show that smoking is a cause of heart disease. Not even when rabbits were subjected to doses of nicotine equivalent to 1,200 cigarettes per day, and not even when human subjects were confined in sealed smoke filled chambers, were researchers able to show any effects that would link smoking with cardiovascular disease. The Smoker and Smoking. We think fair minded people who look at evidence like this might seriously question whether smoking causes heart disease. But that conclusion would still leave a key question unanswered. How else can you explain the statistical correlation? There is one explanation that is attracting the attention of many researchers today. It is called the "constitutional hypothesis." This theory states that there may be hereditary factors which make some people more likely both to get heart disease and to engage in certain kinds of behavior---like smoking. Doctors already know that coronary disease is influenced by heredity; many of us know families in which the disease appears in two or more generations. So it may turn out that the connection between smoking and heart disease lies not in the smoking, but in the smoker. In Search Of Solutions. We're not saying we've proved that smoking doesn't cause heart disease. We're saying our critics have failed to prove that it does. And without such proof, the chain that some say connects smoking with heart disease is missing vitally important link. Independent research into these complex questions will of course go on. And we at R. J. Reynolds will go on providing funds for such research, because no one has a greater interest in the truth than we do. Meanwhile, we can only emphasize that the state of smoking and health remains an open controversy. And we encourage everyone to keep an open mind. R. J. Reynolds tobacco Company.