Full publication of clinical trials presented at a national maternal-fetal medicine meeting: is there a publication bias?

Abstract

We sought to determine the rate and timing of full publication of clinical trials initially presented as abstracts at a national maternal-fetal medicine (MFM) research meeting and identify factors associated with publication status. All abstracts presented over a 3-year period (2000 to 2002) at the Society of MFM Annual Meeting were reviewed. Abstracts reporting outcomes for prospective, interventional research studies with human subjects were included. Multiple electronic databases were searched for evidence of full publication with a minimum of 5-year follow-up. The reporting characteristics of abstracts that were published as full research reports were compared with those not published. During the study period, 2012 abstracts were presented and 90 met all study criteria (4.5%). Of these, 55.6% (n = 50) were subsequently published as full research reports. There were no differences in the use of placebo, randomization, or blinding. Studies reaching full publication had larger sample size (median 174 [12 to 4165] versus 96 [22 to 1039]; p = 0.02) and were more likely to report treatment differences (60% versus 32.5% p = 0.009). After adjusting for confounding factors, the reporting of treatment differences remained associated with full publication (odds ratio 3.3 [95% confidence interval 1.3 to 8.0]; p = 0.01). Full publication of clinical trials occurred more often if treatment differences were present. Positive publication bias exists in MFM research.