Tuesday, April 14, 2009

Epi studies.. what do they mean?!

Commentary on:

“Get smart about science: Conflicting studies about health risks and benefits can drive you crazy. Here’s how to sort through the science”

By Trine Tsoudero, Chicago Tribune, February 16, 2009

The news abounds with stories such as “drinking coffee causes cancer”, “drinking coffee prevents cavities”, and even drinking coffee does not cause cancer or prevent cavities. What?! How can you sift through all of this? More importantly, why do the media report this stuff with such frequency and confidence?

This article brings to light an important fact about these epidemiologic studies: “sometimes findings that sound spectacular may be completely useless to you – though important to other scientists working on the bigger picture.” In other words, epidemiologic studies such as studying the link between drinking wine and heart disease are important to the larger body of science on the issue, but each individual study does not bring definitive answers.

One study this article examines involves investigating coffee drinkers versus non-coffee drinkers and their development of oral, pharyngeal, or esophageal cancers. Although coffee drinkers developed these cancers half as often as non-coffee drinkers, this finding delivers only the relative risk. Looking at the bigger picture, only a few people developed cancer out of this study, so drinking coffee may cut your risk from small to very small.

Second, researchers don’t always take into account other risk factors that may contribute to the finding. Coffee drinkers may have some other characteristic that decreases their risk. Perhaps coffee drinkers are those who can afford to buy coffee at a retail establishment and are therefore higher income level. Or perhaps non-coffee drinkers are more likely to sleep more and be more sedentary.

The bottom line is: realize that epidemiologic studies that you see reported frequently in the media are more likely to be contributing to larger unresolved questions in the scientific world than determining definitive answers for your health. Do more research before diving into that giant full-fat cappuccino every day.

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