Investigation Reveals that CDC Scientists had Serious Concerns about Claim that Obesity was Overtaking Tobacco as Leading Cause of Preventable Death

An internal review of the process by which a March 2004 JAMA article by Centers for Disease Control and Prevention (CDC) authors was reviewed by the agency prior to publication has revealed that at least two senior CDC scientists had "serious concerns" about the scientific validity of the paper that were not adequately addressed prior to publication. More concerning, however, was the suggestion of one investigation committee member that "political pressure" was what led to "insufficient attention given to legitimate criticisms" made by CDC officials who reviewed the paper prior to its submission for publication.

A paper published by authors from CDC, UC Berkeley, and the National Cancer Institute in an April 2005 issue of JAMA reported that obesity causes an estimated 112,000 deaths per year in the United States, down markedly from the estimate of 400,000 reported in the March 2004 article. That 2004 article claimed that "poor diet and physical inactivity may soon overtake tobacco as the leading cause of death." Not surprisingly, the media as well as medical and public health organizations widely disseminated this conclusion as being the main finding of the research.

The CDC's internal review concluded that: "some serious concerns [among senior CDC scientists] remained but at least two of them indicated that they did not push further because, given the prominence and reputation of the authors, they did not feel that it would make any difference. While there does not appear to be any overt or subtle pressure placed on the scientists, the fact that senior scientists had this perception and behaved this way needs to be addressed more explicitly in CDC policies and practices. ... The scientists expressed concerns and did meet with some of the authors but they were not convinced that their perspectives were listened to or that requests for data were acknowledged. Thus, although the authors complied with the clearance policy, the concerns of the center scientists were not addressed as well as they could have been."

One individual investigation team member wrote that: "given the broad and important policy implications of this paper, I am concerned that there may have been insufficient attention given to legitimate criticisms and suggestions made by other CIOs and staff internal to the NCCDPHP. The authors were under some political pressure to get this paper out, but, in hindsight, I believe the paper and its message would have been enhanced by a fuller and more careful consideration of this input."

Another team member concluded that: "The clearance process appeared to have been begun in good faith, though given the dissent, it veered off the path. This likely happened since the Director is a co-author and presumably approved the paper. I think if the scientists had believed that their concerns were being considered, the issue of clearance may not have arisen."

After defending its original paper with its acknowledged scientific inaccuracies for quite some time, CDC has finally admitted that the original estimates were not sound and has updated its estimate of annual obesity-related deaths in the U.S. from 365,000 to 112,000. The agency is also making changes in its clearance policies to help avoid the problems identified by the investigation team in the future.

The Rest of the Story

While scientific inaccuracies and weaknesses are part of research and I do not question the basic merit of the original JAMA article, the results of the internal investigation do raise some serious concerns about whether CDC disregarded legitimate and important scientific concerns for political reasons. It appears that at least some senior scientists had identified significant scientific issues that warranted further discussion, but that these concerns were not pursued adequately prior to submission of the article for publication, either because of the stature of the co-authors (the CDC Director was a co-author) or because of a perception that there was "political pressure to get this paper out" (or both).

What I find most concerning is that there apparently exists within CDC a perception that political factors (including, perhaps, the stature of article authors) overrides legitimate concerns over the scientific integrity of a paper and its conclusions.

It is not entirely clear whether this perception was even correct - had the dissenting reviewers actually pushed further, it is quite possible that the authors (including the CDC Director) might well have revised the paper to incorporate their comments or at least entertained a discussion that addressed, in some satisfactory way, their concerns. But the mere presence of the perception that political factors may trump scientific interests at an agency with a high reputation for the quality of its public health science is alarming.

The investigation also reveals that the authors of the paper were aware of some of the significant concerns regarding the paper methodology and conclusions. Given the uncertainty of the mortality estimates, it is therefore surprising that the authors would have put such stock in the findings that they would take public responsibility for making such a specific and quantitatively precise claim that "poor diet and physical inactivity may soon overtake tobacco as the leading cause of death."

And it is perhaps even more surprising that the CDC Director would have, in the face of apparent awareness of the paper's scientific limitations pointed out by her own senior scientists, proclaimed to the media that one of the paper's findings was in fact that obesity was overtaking tobacco as the leading preventable cause of death. The CDC Director was quoted in the Washington Post as stating that: "Obesity is catching up to tobacco as the leading cause of death in America. If this trend continues it will soon overtake tobacco."

The media clearly perceived the paper's main message as, expressed in the lead sentence of the Post article: "America's weight problem is rapidly overtaking cigarette smoking as the leading cause of preventable deaths, federal health officials reported yesterday." While I know from my own experience that researchers cannot control the way reporters frame a scientific article, it would be difficult to believe that the widespread media framing of the article's conclusions in this rather specific way was not influenced at all by statements made by the paper's senior author.

The rest of the story reveals that this story is less about the number of tobacco- versus obesity-attributable deaths in the U.S. (both are clearly important public health problems, regardless of the numbers) than it is about the integrity of the scientific process and the importance of protecting science from political concerns, even those concerns that may be more perceived than real.