Buffalo, N.Y. -- A new University at Buffalo study of publications in the
world's top five general medical journals finds that when clinical trials do not
account for participants who dropped out, results are biased and may even lead
to incorrect conclusions.
Published recently in the British Medical Journal, the methodological study
open access at http://www.bmj.com/content/344/bmj.e2809
consisted of a systematic analysis of 235 clinical trials published in the world's top five general medical journals between 2005 and 2007 that claimed a statistically significant effect.
"We found that in up to a third of trials, the results that were reported as positive -- in other words, statistically significant -- would become negative -- not statistically significant, if the investigators had appropriately taken into consideration those participants who were lost to follow-up," says Elie A. Akl, MD, MPH, PhD, lead author, and associate professor of medicine, family medicine and social and preventive medicine at the University at Buffalo School of Medicine and Biomedical Sciences and School of Public Health and Health Professions. He also has an appointment at McMaster University.
"In other words, one of three claims of effectiveness of interventions made in top general medical journals might be wrong," he says...