Understanding the risks

I'm a stats junkie, and I love to go to the source whenever there's news about research. The Web makes it easy to go deeper than the headlines and sound bites -- and too often, a little digging turns up the real news: That the reporter didn't really understand what the researcher had discovered. Oversimplification takes a toll.

That's why I like the innovative charts that accompany a paper published in the June Journal of the National Cancer Institute. They provide a broader perspective than most risk calculators, covering 10 different causes of death while differentiating between nonsmokers, smokers and former smokers -- at various ages -- and by gender.

With this method, it's apparent that a 35-year-old male smoker is seven times as likely to die of heart disease as a nonsmoker the same age. Of course, some hardy smokers will manage to survive into their 70s, and by age 75 smokers and nonsmokers have nearly the same risk of death from heart disease. For women who have never smoked, the magnitudes of the 10-year risks of death from breast cancer and heart disease are similar until age 60; from this age on, heart disease represents the single largest cause of death. For women who smoke, the chance of dying from heart disease or lung cancer exceeds the chance of dying from breast cancer from age 40 on (and does so by at least a factor of 5 after age 55). This is especially significant given that cancer risk generally increases with age.

Paper co-author Lisa M. Schwartz, an associate professor of medicine at Dartmouth University, said the the 10-year risk increments of the charts are especially informative. “Often numbers are presented as lifetime statistics, which make the risk look too large, or as one-year statistics, which make the risk look too small. The charts provide the information you need to understand a risk, and whether to consider taking some action to reduce it.”