Does this come as a surprise!
Over half of all supporting trials for FDA-approved drugs remained unpublished greater than 5 y after approval. Pivotal trials and trials with statistically significant results and larger sample sizes are more likely to be published. Selective reporting of trial results exists for commonly marketed drugs.
Reference: Public Library of Science
Comments from the author:
We found that there was indeed a pattern that favorable studies were more likely to be published than unfavorable trials,” said Ida Sim, associate professor of internal medicine at UCSF and the lead author.
Reference: Bloomberg Science
Further Reading: The Great Beyond, Bad Science, Respectful Insolence, Science Based Medicine
