Collider bias and the obesity paradox

Abstract

Obesity paradoxes have been reported in many diseases to date. As the wording "paradox" indicates, our intuition rejects the hypothesis that obese people have a better life expectancy or fewer cardiovascular events. One of the most plausible explanations for the obesity paradox is collider bias, but controversy about this is ongoing. If the findings of the original research are affected by collider bias, meta-analyses of that research will also be affected by the same bias. It is to be hoped that the use of appropriate analytical techniques will enable the true nature of the obesity bias to become clear.

Keywords: cardiovascular diseases; neoplasms; obesity; selection bias; systematic review.