Preliminary reports and the rates of publication of follow-up reports in peer-reviewed, indexed journals

Purpose. To test the hypothesis that articles published as "preliminary" or "pilot" reports are followed by more definitive publications in only a min ority of cases. Method. A survey of Medline was performed for reports published in 1992 in journals listed in the Abridged Index Medicus that had the word "preliminar y" or "pilot" in the title. For identified reports, a Medline search of pub lications in 1992 through 1999 was performed, using lead author's name, sec ond author's name, and senior (last) author's name, and at least one keywor d based on the publication title. Preliminary and pilot publications were s ubdivided by type of study (controlled clinical study, case series, laborat ory or nonclinical) and by the report of either positive or negative result s. Rates of publication based on study design and publication bias were com pared using the chi-square test for statistical significance. Results. The rate of publication of follow-up reports within seven years of the initial publication was 21%. Follow-up studies of controlled clinical studies (40%) were published more frequently than were those of laboratory or nonclinical studies (31%) or case series (22%), but these differences we re not significant (P >.10). There was no statistically significant differe nce in follow-up publication rates based on publication bias. Conclusion. Only 27% of studies published as preliminary or pilot reports w ere subsequently followed by a more definitive publication. While the words preliminary and pilot suggest that publication of further, refined work is pending, this is often not the case.