CV biomarker study finds evidence of bias, exaggeration in the field

Scanning the field of biomarker research for cardiovascular disease, a group of investigators has found some compelling data that suggest the effect of the biomarkers is regularly exaggerated, with signs of bias in the reports. And that clearly could be hurting the medical field's understanding of the biomarkers' significance.

The investigators identified 59 available meta-analyses for review with 49 claiming statistically significant results, according to a report in Cardiology Today. But the largest studies with the most subjects had the smallest effects, with a host of smaller studies claiming the most dramatic results. And that indicates bias in the selection of which reports were published, tilting the field toward the positive and away from the negative. 

"We found strong evidence to suggest the effect of biomarkers is exaggerated because the largest studies, which one would expect to produce the most stable estimates, consistently showed smaller effects," researcher Ioanna Tzoulaki wrote. "In most meta-analyses, too many single studies had reported 'positive' results compared with what would be expected on the basis of the results of the largest study. This suggests that small studies with 'negative' results remain unpublished or that their results are distorted during analysis and reporting to seem more prominent."

Steven Nissen

Cardiology expert Steven Nissen concluded that the bias was clear.

"In a few cases, the evidence for publication bias was extreme," Nissen noted in an editorial. "For example, routine measurement of carotid intima-medial thickness has been advocated as a means to predict CV risk and select patients for treatment, but the current analysis demonstrates a greater than 12-fold excess in the number of favorable studies compared with what would be predicted … We must emphasize to colleges and trainees that all studies contribute to scientific understanding."

- here's the report from Cardiology Today