Public Release: 

Methods used in reporting results of new treatments may be misleading

University of California - Davis Health System

(SACRAMENTO, Calif.) -- Articles appearing in five top medical journals often present results in a way that may be misleading, according to two UC Davis School of Medicine researchers.

"The public expects advertisers to use the most flattering statistics to bolster claims of effectiveness in promoting products," said UC Davis research and family physician Jim Nuovo. "However, most of us expect that medical journals will provide complete reporting of all important aspects of research on a new treatment. Without more comparative data, readers may be basing their decisions to use a new treatment on incomplete information."

Nuovo and family physician Joy Melnikow, who are both faculty in UC Davis School of Medicine's Department of Family and Community Medicine, reviewed 359 articles involving new treatments published between 1989 and 1998 in the frequently cited journals: the Annals of Internal Medicine, British Journal of Medicine, Journal of American Medical Association, The Lancet and the New England Journal of Medicine. Results of the UC Davis review are published as a brief report in the June 5 edition of JAMA.

"Our review of the literature showed that, in the majority of cases, only the most favorable statistic -- the relative-risk reduction -- was used when reporting the results of these studies," Nuovo said.

Of the 359 articles discussing the results of randomized trials -- considered the gold standard for assessing new treatments -- only eight reported a more explicit statistic, the "number needed to treat," and only 18 used "absolute-risk reduction."

Number needed to treat is the statistical number of patients who may be subjected to a bad outcome, such as death, stroke or heart attack, before the new treatment prevents a bad outcome. For example, if a drug has a number needed to treat of five, it means physicians would statistically have to treat five people with the drug before preventing a bad outcome.

"Absolute-risk reduction" measures the actual difference between the treatment results compared to the placebo group. "Relative-risk reduction" is the percentage difference between the treatment results and the placebo group, and typically is the most favorable statistic.

"These additional measurements are important because we know that the way that information is presented affects the acceptance of treatment for both patients and physicians," Nuovo said.

Nuovo also suggested that medical journals should require their authors to follow the established guidelines that include these additional measurements. Number-needed-to-treat and absolute-risk reduction are part of the Consolidated Standards of Reporting Trials statement, which medical journals are to follow in publishing research.

"No single number can entirely explain the results of a trial," Nuovo said, "so it would be in the best interest of physicians and their patients to require complete reporting of the potential benefits and the potential risks of any new treatment. Doing so should increase the chance of the appropriate implementation of research on new treatments."


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