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I have shocking news. Smoking is very very bad for you.

In 1964 the US Surgeon General issued a report summarizing the known adverse health effects of smoking. At that time about 40% of American adults smoked. A widespread campaign followed informing Americans about the link between smoking and lung cancer, emphysema, stroke, and heart attacks. Federal law required the placement of health warnings on cigarette packages, and school children all learned about the adverse health effects of smoking.

By 2010 the prevalence of smoking decreased to 19% of American adults, mostly because of more people quitting (rather than fewer people starting). But from 2004 to 2010 the prevalence of smoking has changed little. We seem to have reached a steady state, a nadir of smoking despite the now well-known health hazards. And while smokers were much more representative of the general population in the 1960s, they are now disproportionately poor and less educated. Current smokers are also on average younger than non-smokers, since so many smokers quit as they get older.

This week the New England Journal of Medicine (NEJM) published two studies that attempted to quantify the differences in longevity between smokers and non-smokers. The studies followed hundreds of thousands of men and women and compared the information about their smoking status to their longevity and cause of death.

The results were fairly dramatic. On average, those who never smoked live over 10 years longer than those who continue to smoke their whole lives. For those between 25 and 79 years old, the death rate for smokers is three times that of those who never smoked. Those who quit also did much better than those who didn’t. Those who quit between the ages of 25 and 34 lived 10 years longer than those who continued smoking, almost reaching the longevity of those who never smoked. The benefit of quitting decreased with increasing age, but never disappeared. Smokers who quit between the ages of 55 and 64 still lived 4 years longer than those who kept smoking.

My regular readers will recognize that these are not randomized studies, and they therefore deserve some skepticism. That’s true. One study was controlled for alcohol use, educational level, and body mass index, but one can easily imagine other confounding factors (poverty, poor access to health care) that may be more prevalent among smokers and independently increase the risk of death. So we can’t be certain that the effect of smoking is as large as the study suggests. Still, the studies add to a mountain of evidence that has already established the risk of smoking. And a randomized study will never be done, so we will never be able to measure the risk exactly.

The bottom line is that smoking is likely to cut your life short. Quitting at any age has benefits. Sooner is better.

The author of an accompanying editorial in the same NEJM issue concludes with this concern.

Because smoking has become a stigmatized behavior concentrated among persons of low social status, it risks becoming invisible to those who set health policies and research priorities. Yet, the need for greater attention to the policies known to reduce the prevalence of smoking remains urgent. As former Australian Health Minister Nicola Roxon has said, “We are killing people by not acting.”

But the increasing “invisibility” and disenfranchisement of smokers seems to me inevitable. For half a century we have very successfully educated people about the risks of smoking. We have waged a campaign that has made it clear that smoking is hazardous and we have tried to make it uncool. We cannot simultaneously applaud our important success while being surprised that those most resistant to the message are those whom information and solid judgment are least likely to reach.

All diseases that are predominantly acquired through behaviors, like HIV or cervical cancer, follow the same pattern over time. As education about prevention of the disease spreads, those who have access to information and value their health will stop contracting the disease. A generation later those who are still engaging in the risky behaviors are very difficult to reach. Few problems are more intractable than people in free societies choosing to harm themselves.

Further progress in decreasing the prevalence of smoking is likely to be incremental and slow. I suspect further attempts at addressing this problem through policy will involve tradeoffs, not solutions.

Learn more:

Smokers Lose 10-Plus Years of Life, Studies Find (Wall Street Journal)
Quitting smoking prolongs life at any age (LA Times)
Putting a Number on Smoking’s Toll (NY Times)
21st-Century Hazards of Smoking and Benefits of Cessation in the United States (NEJM article)
50-Year Trends in Smoking-Related Mortality in the United States (NEJM article)
New Evidence That Cigarette Smoking Remains the Most Important Health Hazard (NEJM editorial)

Tangential Miscellany

Seven years and over 300 posts ago I decided to start writing a weekly health news blog. Since then my posts have been republished in half a dozen publications, started some fascinating debates, and I hope educated and stimulated you. Thank you for reading. I promise to try not to bore you in the next seven years.