CDC Report Details Causes of Improper Release of Study on Obesity

A CDC study published in March 2004 that might have overstated the number of annual obesity-related deaths in the United States was improperly released because of "miscommunication, bureaucratic snafus and acquiescence from dissenting scientists," according to a report posted on Wednesday on the agency Web site following an internal investigation, the Los Angeles Times reports (Mestel, Los Angeles Times, 2/10). The study, which was published in the Journal of the American Medical Association, found that annual obesity-related deaths increased by 100,000 between 1990 and 2000 to 400,000.

For the study, Ali Mokdad, chief of the behavioral surveillance branch at CDC, and colleagues reviewed U.S. mortality data from 2000 and studies on the role that lifestyle factors have on the development of conditions such as diabetes or stroke to estimate the number of deaths attributable to lifestyle. Researchers also compared their data with a similar study conducted with U.S. mortality data from 1990. The study found that an estimated 400,000 U.S. residents died from causes related to dietary habits and sedentary lifestyles -- 33% more than in 1990, when obesity contributed 300,000 deaths. In comparison, the study found that 435,000 U.S. residents died from smoking or exposure to tobacco in 2000, compared with 400,000 in 1990.

Researchers concluded that obesity would become the leading cause of preventable death by this year. The study led to an HHS campaign against obesity and an increased focus on obesity research at NIH. However, according to a letter from researchers published last month in JAMA, a computer error caused the study to overstate by about 35,000 the number of annual obesity-related deaths in the United States in 2000. The letter also said that obesity will not overtake tobacco as the leading cause of preventable death by this year (California Healthline, 1/19).

After publication last March, critics contended that that the study overstated the number of annual obesity-related deaths in the United States as a result of improper methodology. In response, CDC launched an internal investigation, the conclusions of which appear in the report posted on Wednesday. The report found that three agency research centers had initially refused to approve the study for publication.

In addition, the report found that researchers "incorrectly assumed that objections to their work had disappeared when they didn't hear back from certain critics," the Times reports. Some scientists who objected to the study said 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."

The report recommended that CDC revise policies and practices to encourage scientists who object to studies to express their opinions, improve procedures used to approve studies for publication and improve methods used to calculate causes of death. CDC spokesperson Tom Skinner said that the report "led us to the realization that there are a number of steps we can take to improve our clearance process at the CDC, which is only going to strengthen and enhance our science" (Los Angeles Times, 2/10).