Association between time interval to publication and statistical significance

Abstract

Context: Studies have shown that reports from clinical trials with statistically significant results tend to be submitted and published more rapidly than reports from studies with null or insignificant findings.

Methods: We wanted to determine whether manuscripts reporting positive results from controlled clinical trials are published more quickly than those reporting negative results. We tracked manuscripts from submission to JAMA until the publication decision. We classified results as positive if a statistically significant difference was reported for the primary outcome. Manuscripts were further classified according to indicators of methodologic quality and other study characteristics. We included manuscripts if they were submitted from February 1996 through August 1999, reported results of a prospective study in which participants were assigned to a treatment or comparison group, used statistical tests to compare differences between groups, and were accepted for publication.

Results: One hundred thirty-three manuscripts met our inclusion criteria, 78 (59%) reported positive results, 51 (38%) reported negative results. We were unable to classify the direction of results for 4 articles (3%). The time interval between submission and publication was not associated with positive results: median time between submission and publication was 7.8 months for reports with positive vs 7.6 months for reports with negative results (P =.44). Time to publication also was not associated with any marker of study quality or study characteristic.

Conclusions: Among 133 published controlled trials, time to publication was not associated with statistical significance, methodologic quality, or other study characteristics.