Systematic reviews of the published medical literature may often be unreliable due to chronic publication bias, according to a study in PLOS One.
A team of German, Swiss and American researchers compiled a list of studies that had been approved by research ethics committees (RECs) or included in trial registries, and sought to determine what percentage of these had been subsequently published, and what if any patterns were detectable in whether they’d been published.
“Overall, only about half of clinical and preclinical studies approved by RECs or included in trial registries are published as full journal articles,” the researchers wrote. “We also found evidence for dissemination bias in that studies with statistically significant results were more likely to be published than those without.”
(Full text) (Schmucker, Christine et al. Extent of Non-Publication in Cohorts of Studies Approved by Research Ethics Committees or Included in Trial Registries. PLOS One. December 23, 2014. DOI: 10.1371/journal.pone.0114023)