German scientists trade barbs over noise study

Researcher denies manipulating published data linking noise to heart attack

By | January 18, 2006

Two research teams used different methods to analyze the same set of data, now one is accusing the other of fraud. The accused, Stefan Willich, a scientist at Europe?s largest medical school, Germany?s Berlin Charité, denies manipulating research data for an article in the European Heart Journal linking high noise levels with an increased risk of heart attacks. ?Our research and conclusions were based on high international scientific standards,? Willich, director of Berlin Charité?s Institute for Social Medicine, Epidemiology, and Health Economics, told The Scientist. In January 2005, Wolfgang Babisch, a scientist at Germany?s Federal Environmental Agency (UBA), published an article in the journal Epidemiology using the same data as Willich ? but finding very different conclusions. Willich and his team concluded that high noise levels increased the risk of heart attacks by 50% in men, and 200% in women. Babisch?s team, in contrast, concluded that high noise levels increased the risk of heart attacks in men by about 30%, and had basically no effect on women. Babsich told The Scientist that Willich?s conclusions are based on ?bad science.? He noted that the two teams originally planned to publish a joint article on the research, but after the disagreement, this no longer became possible. Both studies used data from a case-control study of 4115 patients (3054 men) admitted between 1998 to 2001 to major hospitals in Berlin. Approximately half of the patients were diagnosed with heart attack, and the researchers analyzed all participants? exposure to noise at work and home. Willich was principal investigator and responsible for the design, conduct, and analysis of the study. Last week, the UBA and the Federal Institute for Occupational Safety and Health (BAuA) issued a press release denouncing Willich?s article. Babsich has also submitted a letter to the editor of the European Heart Journal, in which he says Willich and his team ?have seriously mistreated our noise data, which results in a false interpretation of the findings.? Willich said he is crafting a letter in response to Babisch?s. A spokeswoman for the European Heart Journal said she believed Willich?s paper was reviewed by two peer reviewers and the journals?s statistician, and received a ?very favorable review.? She noted in an Email that both letters to the editor would be published in early March. The relationship between Babisch and Willich soured in 2004 when the scientists disagreed on how to analyze the data about noise pollution?s effect on cardiovascular health. Some 40% of total study participants lived on Berlin?s major noisy traffic arteries (over 60 decibels), 10% on side streets near busy streets, and 50% on side streets not near busy streets. The core of the researchers? dispute centers on the analysis of data from the participants who live on side streets away from busy roads. Since no official traffic noise maps provide data for people living on side streets away from busy roads, Willich?s group used the 10% in side streets near major streets as the study?s reference group, and reported the people living on side streets without noise readings as a separate group with missing values. Babisch, however, estimated that people living away from busy roads experience noise levels below 60 decibels, and his team combined all people living on side streets ? near and far from high-trafficked streets ? into one reference group. He alleges that Willich excluded the people living away from busy roads from the reference group in order to manipulate the data, and show that high noise levels greatly increase the risk of heart attacks in both men and women. Willich, however, said he made the right decision. ?How can you use a reference group for which you don?t know the true noise exposure? It?s like putting on a blindfold, and that is not good science.? By Ned Stafford e-mail: Links within this article Stefan Willich Berlin Charité S. N. Willich et al, ?Noise burden and the risk of myocardial infarction,? European Heart Journal, November 24, 2005. PM_ID: 16308324. W. Babisch et al, ?Traffic noise and risk of myocardial infarction,? Epidemiology, January 2005. PM_ID: 15613943 Federal Environmental Agency Federal Institute for Occupational Safety and Health UBA and BAuA joint press release, January 2006. Loud noise linked to high blood pressure and heart attacks

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