The principles we espouse on Science-Based Medicine are vitally important, but some of the subjects we address are not so important in the big scheme of things. Homeopathy and electrodermal diagnostic devices don’t actually harm very many people. For today’s post, I’m going to follow the Willie Sutton rule and go where the money is, so to speak.
Smoking is the leading preventable cause of death. No prospective double blind randomized controlled studies have been done, or ever could be done; but a mountain of evidence converging from many avenues has established the health dangers of smoking beyond any doubt. Hill’s criteria of causation have been amply fulfilled. Smoking causes 90% of all deaths from lung cancer and chronic obstructive pulmonary disease (COPD). It increases the risk of coronary heart disease, stroke, several types of cancer, infertility, stillbirth, sudden infant death syndrome (SIDS), osteoporosis, and premature skin aging (wrinkles). The dangers of second-hand smoke have been amply documented, and where smoke-free laws have been passed there has been a drop in the incidence of heart attacks and of emergency room visits for children with asthma.
Two new studies published in The New England Journal of Medicine reinforce what we already knew and offer both good news and bad news. (more…)
Ever since news of the harmful effects of tobacco smoke hit the public consciousess around the middle of the 20th century the tobacco industry and others have been looking for a “healthy” alternative. Are e-cigarettes just latest in a list of failed attempts to make smoking safe?
In case you are a new visitor to our planet (welcome) using tobacco products has been determined to be a significant risk factor in developing certain kinds of lung cancer and vascular disease, including strokes and heart attacks (the top three killers). The tobacco industry initially tried desperately to deny or downplay the scientific evidence for the health risks of smoking, engaging in a campaign of doubt and confusion, but those efforts ultimately failed.
Some companies marketed light, low tar, and filtered cigarettes with the claim, direct or implied, that they were a more healthful alternative to regular cigarettes. However, there has never been convincing evidence that such cigarettes are less of a health risk. Still, the marketing stuck and now 90% of all cigarettes sold are filtered.
Three kids on the same block were diagnosed with leukemia last year. That couldn’t happen just by chance, could it? There MUST be something in the environment that caused it (power lines, the chemical plant down the street, asbestos in their school, iPods, Twinkies?). Quick, let’s measure everything we can think of and compare exposures to other blocks and find an explanation.
That may be the common reaction, and it may seem plausible to the general public, but it’s not good science.
I have just read a book that does a great job of elucidating the pitfalls of epidemiologic studies, the problematic interface between science and emotion-laden public concerns, and the way environmental hazards have been hyped far beyond the evidence. Hyping Health Risks: Environmental Hazards in Daily Life and the Science of Epidemiology by Geoffrey C. Kabat.
He covers the uses, strengths and limitations of epidemiology, discusses the pros and cons of different study designs, and explains how to judge whether an association is causal.