TUESDAY, May 31 (HealthDay News) -- A bevy of studies linking genes, proteins and other so-called "biomarkers" with certain diseases has vastly overrated the connections, new research suggests.
Analyzing 35 of the most frequently cited studies published between 1991 and 2006 in 10 renowned biomedical journals, study authors found that fewer than half of the biomarkers studied revealed statistically significant links to disease in larger follow-up trials.
Only 20 percent of the selected associations increased a patient's relative risk for a condition by more than 35 percent, the researchers found.
"I'm not terribly surprised because I had seen on a case-by-case basis these highly cited biomarkers that were not keeping the promises that had been made," said study author Dr. John Ioannidis, chief of the Stanford Prevention Research Center in Palo Alto, Calif. "I think the key message for researchers is that one should not depend on the results of a single study, no matter how spectacular the results are. We need to see replication and look at the bigger picture."
The study is published in the June 1 issue of the Journal of the American Medical Association.
The studies, each of which had been referenced in at least 400 later papers, looked at the links between biomarkers -- including specific genes or germs, levels of blood proteins and other molecules -- and the likelihood of developing conditions such as cancer and heart disease.
Because of the common scientific practice of citing previous supporting research in new studies, landmark research is often repeatedly referenced, making its results appear incontrovertible, Ioannidis said. But larger subsequent trials often report less spectacular or even statistically insignificant links between the same biomarkers and certain diseases.
Ioannidis noted that studies with larger numbers of patients, or
All rights reserved