Sunday, March 13, 2011

Big Fat Funnel Plot?

I received this link from a friend this weekend, a very interesting article by Kristin Wartman:

This article highlights the changes in opinion that some nutrition researchers have had lately, now that better data are starting to come in.  And, it is actually coming from some of the Harvard boys!  Shocking!
Here's a paper by Frank Hu, a prominent Harvard researcher who has been changing the tune lately:
And the clif notes for people who hate to read studies:

1.  We did a study where we looked at a bunch of studies done by other people regarding saturated fat and heart disease risk.
2.  We didn't find anything
3.  Oh, wait, we did find something.  We found publication bias!  We left that tidbit out of the abstract.

What's publication bias????  Well, they showed a fancy funnel plot, and it failed to look like a funnel, but what that really means is that researchers who found a positive correlation between saturated fat and CVD risk were more likely to get their papers published.  Why?  Probably because the biased "peers" who controlled entry into the top journals wouldn't let the other studies in.

It is really interesting to see Dr. Hu changing his position.  He has other studies like this one:
This study was blasted by others, and for the way the media handled it.  This is another one of the observational epidemiological studies some can mis-use when they confuse correlation with cause.  The media picked this up and inaccurately reported that if you eat less meat you will have less disease.

Here's a nice article about the whole messy saturated fat/heart disease debate, and some additional links.  An especially good link is to the Dr. Eades blog, where he uncovers the reporting bias by the media.  Dr. Eades has a number of blog posts describing the widespread incidence of reporting bias. And I think it is pretty interesting stuff to read.  I'd bet that if the media reports could be meta-analyzed, they would show no funnel shape either.  Here's the link:

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