- The Washington Times - Tuesday, July 12, 2005

CHICAGO (AP) — Here’s some medical news you can trust: A new study confirms that what doctors once said was good for you often turns out to be bad — or at least not as great as initially thought.

Researchers reviewed 45 highly publicized studies, which appeared in three influential medical journals from 1990 to 2003, that initially said a drug or other treatment worked.

Subsequent research contradicted results of seven studies — 16 percent — and reported weaker results for seven, an additional 16 percent. That means nearly one-third of the original results did not hold up, according to the study in today’s Journal of the American Medical Association.

“Contradicted and potentially exaggerated findings are not uncommon in the most visible and most influential original clinical research,” said study author Dr. John Ioannidis, a researcher at the University of Ioannina in Greece.

Specialists say the study is a reminder to doctors and patients that they should not put too much stock in a single study and should understand that treatments often become obsolete with medical advances.



“A single study is not the final word, and that is an important message,” said editors at the New England Journal of Medicine.

The refuted studies dealt with a wide range of drugs and treatments. Hormone pills once were thought to protect menopausal women from heart disease but later were shown to do the opposite. Contrary to initial results, vitamin E pills have not been shown to prevent heart attacks.

Contradictions also included a study that found nitric oxide does not improve survival rate among patients with respiratory failure, despite earlier assertions. And a study suggested that an antibody treatment did not improve survival chances in certain sepsis patients; a smaller previous study found the opposite.

Dr. Ioannidis had an important but not reassuring caveat: “There’s no proof that the subsequent studies … were necessarily correct.”

But he noted that in all 14 cases in which results were contradicted or weakened, the subsequent studies were either larger or better designed. Also, none of the contradicted treatments is currently recommended by medical guidelines.

Dr. Ioannidis’ study examined research in the New England Journal of Medicine, Lancet and JAMA.

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