Publication bias in pediatric hematology and oncology: analysis of abstracts presented at the annual meeting of the American Society of Pediatric Hematology and Oncology.

Publication bias (PB) is a threat to the validity of medical literature, and has not been studied in the field of pediatric hematology/oncology. We analyzed the abstracts presented at the 2005 American Society of Pediatric Hematology/Oncology annual meeting to assess for PB. Abstracts were categorized by type of research, number of centers, funding status, presentation format, sample size, statistical significance, and the direction of results. Publication status was determined by searching PubMed. Thirty nine abstracts (51%) were categorized as clinical studies, 67 (36%) as basic research, and 24 (13%) as others. One hundred and twenty three abstracts (67%) were considered to have positive results, 14 (8%) negative results, and 47 (25%) with neutral or not stated results. About 62% of the abstracts were published in peer-reviewed journals at a median time to publication of 19 months (IQR = 11-29 months). Abstracts with positive results were more likely to get published than others (combined negative and neutral results) (P = .002). Factors like sample size, number of centers, or statistical significance reporting did not affect the publication rate. Our data suggests the existence of PB in the field of pediatric hematology/oncology. Still, further analysis of other international meetings is needed to validate our findings.