Introduction: Since June 2005, the University Hospital Medical Information Network-Clinical Trial Registry (UMIN-CTR) has been an International Committee of Medical Journal Editors (ICMJE)-approved clinical trial registry in Japan. The number of clinical trials registered in the UMIN-CTR has increased annually. To date, no report exists regarding the publishing of clinical trials registered in the UMIN-CTR. Therefore, we evaluated the publication frequency of clinical trials registered in the UMIN-CTR in Japan.
Methods: We targeted trials that assessed the treatment effect of chemotherapy or molecular targeting drugs for lung cancer. We included trials registered between June 2005 and January 2010, and identified published trials through a computer-based search of MEDLINE and Google Scholar. The cumulative publication rate of the trials was calculated using Kaplan-Meier analysis.
Results: In our study, 179 trials met the inclusion criteria. Of these, 46.4% (83/179) trials were published by the end of the cut-off period. With regard to publication, differences existed between the information recorded in the UMIN-CTR database and the actual searched results. The publication rate between groups was insignificantly different; however, whether a clinical study group did or did not conduct a trial differed significantly (53.3% vs. 36.1%; P = 0.024). Phase II studies with positive results were more likely to be published (84.4%); however, the overall publication rate was low (41.8%), which may reflect publication bias.
Conclusions: The UMIN-CTR fundamentally functions as the unique ICMJE-approved clinical trial registry in Japan. However, it seems insufficient to require it as the official clinical database.