Accurate information on harms of medical interventions is essential for evidence-based practice. Most newly introduced treatments usually have small, incremental benefits, if any, against already available interventions, and differences in the profile of harms should play a key role on treatment choice.

So leads an editorial in today's edition of the Archives of Internal Medicine by John P.A. Ionannidis, the Greek physician-researcher most famous for his 2005 article in PLoS Medicine that explained "why most research findings are false." His editorial was in response to a new study showing how authors in major medical journals often ignore risk information when reporting clinical trial results. The study, reported by MedPage Today here, found 47 percent of 133 trials reported in journals like the New England Journal of Medicine, the Journal of the American Medical Association, the British Medical Journal and Lancet omitted numbers of study withdrawals because of adverse effects, while 27 percent failed to describe the seriousness of the adverse effects that were observed.

Why? "Perhaps conflicts of interest and marketing rather than science have shaped even the often accepted standard that randomized trials study primarily effectiveness," Ionannidis concludes, "whereas information on harms from medical interventions can wait for case reports and nonrandomized studies."

That just won't do, he says. "Nonrandomized data are very helpful, but they have limitations, and many harms will remain long undetected if we just wait for spontaneous reporting and other nonrandomized research to reveal them. In an environment where effectiveness benefits are small and shrinking, the randomized trials agenda may need to reprogram its whole mission, including its reporting, toward better understanding of harms."