Publication bias in gastroenterological research – a retrospective cohort study based on abstracts submitted to a scientific meeting

Antje Timmer, Robert J Hilsden, John Cole, David Hailey, Lloyd R Sutherland

The aim of this study was to examine the determinants of publication and whether publication bias occurred in gastroenterological research. A random sample of abstracts submitted to DDW, the major GI meeting (1992-1995) was evaluated. The publication status was determined by database searches, complemented by a mailed survey to abstract authors. Determinants of publication were examined by Cox proportional hazards model and multiple logistic regression. The sample included abstracts on 326 controlled clinical trials (CCT), 336 other clinical research reports (OCR), and 174 basic science studies (BSS). 392 abstracts (47%) were published as full papers. Acceptance for presentation at the meeting was a strong predictor of subsequent publication for all research types (overall, 54% vs. 34%, OR 2.3, 95% CI 1.7 to 3.1). In the multivariate analysis, multi-center status was found to predict publication (OR 2.8, 95% CI 1.6-4.9). There was no significant association between direction of study results and subsequent publication. Studies were less likely to be published in high impact journals if the results were not statistically significant (OR 0.5, 95 CI 95% 0.3-0.6). The author survey identified lack of time or interest as the main reason for failure to publish. Abstracts which were selected for presentation at the DDW are more likely to be followed by full publications. The statistical significance of the study results was not found to be a predictor of publication but influences the chances for high impact publication.