ST. PAUL, Minn. – Stroke studies where the results are positive or neutral are more likely to get published than studies with negative results, according to an analysis of 45 years worth of studies published in the September 26, 2006, issue of Neurology, the scientific journal of the American Academy of Neurology.
"Science is best served when the results of all studies, whether positive or negative, are published in peer-reviewed journals," said author David S. Liebeskind, MD, of UCLA Stroke Center in Los Angeles, California, and a member of the American Academy of Neurology. "This is evidence of publication bias. Failure to publish negative results deprives doctors, patients, and future researchers of valuable data and intellectual discoveries."
The analysis looked at all studies for treatments for acute ischemic stroke. Eighty percent of strokes are ischemic; they are caused by sudden loss of blood flow to the brain. Only studies published in English were included in the analysis.
The analysis found that three out of four unpublished studies, or 75 percent, had negative, or harmful, results, while only six percent of the 178 published studies had negative, or harmful, results.
"Our analysis showed that in addition to these four known unpublished studies, there likely are more small studies with negative results that are not being published," Liebeskind said. "There is a conspicuous lack of small, negative studies, suggesting that publication bias has affected both corporate and non-corporate studies."
"Although the extent of publication bias detected was modest, it is concerning. Corporate profit incentives and academic concerns must be overridden by our ethical obligation to the people who participate in these studies, future patients and the scientific community. Rapid publication of negative studies may spare patients from exposure to useless or even harmful treatments, and from participation in futile studies."
Liebeskind said the findings support the need for registration of all clinical studies before they begin. Neurology requires investigators to register their clinical trials in a public trials registry.
The study was supported in part by a National Stroke Association Research Fellowship Award and by grants from the National Institutes of Health.
The American Academy of Neurology, an association of more than 19,000 neurologists and neuroscience professionals, is dedicated to improving patient care through education and research. A neurologist is a doctor with specialized training in diagnosing, treating, and managing disorders of the brain and nervous system such as Alzheimer's disease, epilepsy, Parkinson disease, multiple sclerosis, and stroke. For more information about the American Academy of Neurology, visit www.aan.com.
Journal
Neurology