Causality, Correlation, and Cardiac Disease

The dangers of cigarette smoking are not disputed and yet it remains a multibillion dollar industry.1 Despite their first-hand experience with complications of cigarette smoking, even the occasional physician continues to smoke.2 Furthermore, alternatives to traditional cigarette smoking, such as e-cigarette use, are on the rise.3 This illustrates the ongoing public appetite for smoking and reinforces the strong public interest in continuing to better understand relationships between smoking and disease. See Article by Nadruz et al Cigarette smoking can cause disease directly, but smoking is also associated with a suite of health behaviors and socioeconomic determinants of health.4 If we knew definitively that cigarettes caused heart failure, a public health campaign to reduce heart failure could have a precise and targeted mandate. On the contrary, if we knew definitively that cigarette smoking was merely a marker of a man or woman’s exposure to outdoor air pollution, access to healthcare, a healthy diet, or medication adherence then the public health approach might be much different. This is not meant to diminish the importance of smoking cessation. Smoking is known to cause many diseases, and cessation remains a vitally important pillar of public health, but it is important to try and understand where it fits into a complex, multifaceted, and nuanced understanding of disease causation.1 The importance of trying to understand causality is a core principle in epidemiology and can be complex. At a time when the world was convinced that improved life expectancy was a direct result of germ theory, antibiotics, and medical science, the microbiologist Rene Dubos demonstrated that mortality had been falling for several decades before these medical advances. …