Comment This is why I hate academia (Score 1) 220
Ok first, even though as about 20 people have posted "correlation does not equal causation", the authors are also aware of this and therefore control for many other things. So whenever you doubt the causual relationship claimed by a study, it's always good to actually read the paper.
However in this case, the "correlation does not equal causation" crowd were right, and the authors even admit it
Fourth, residual confounding may still exist even though we adjusted for all the potential confounders available in the present study. Smoking is likely to be one of the most important factors to cause residual confounding in this investigation. We therefore stratified the analysis by smoking status and the results are shown in Supplemental Figures 1 and 2, available online at http://www.mayoclinicproceedings.org./ We did not [my emphasis] observe the significant association between coffee consumption and all-cause mortality both in current smokers and non-current smokers.
Not only do they find that the relationship goes away once you look at just smokers, or just non-smokers, but they hide this fact in a single sentence, and don't even comment on this result.