Missing Evidence: Exploring Unpublished Trials in Victoria, Australia

Abstract

Background: Clinical trial registries were established to improve the transparency and completeness of clinical trial reporting and a number of policies have been introduced to encourage or mandate their use. While prospective trial registration has been endorsed in Australia, there is currently no legal requirement for researchers to register or communicate findings from clinical trials. There has also been, to the best of our knowledge, no analysis previously undertaken on publication rates for clinical trials performed in Australia. Aim: We aimed to determine the proportion of clinical trials that remain 'unpublished' in Victoria, Australia´s second most populous state, between 2009 and 2013. Methods: We used data reported to Cancer Council Victoria's Cancer Trials Management Scheme (CTMS) between 2009 and 2013, to identify trials that had recruited a new patient or recorded any follow-up patient activity in the specified time period. Using this data, we conducted a systematic search of ClinicalTrials.gov , the Australia and New Zealand Clinical Trials Registry (ANZCTR), PubMed and Google for records of the trial. Trial registration numbers, acronyms and scientific titles were used as primary search terms. Results were characterized by type of publication (i.e., whether it was an accredited scientific paper or other) and source location. Results: Of the trials reported to the CTMS between 2009 and 2013, 777 trials were included in this investigation; the majority (58.8%) were randomized controlled trials (RCTs). Compared with previously published findings, communication of trial results in this study was high; 70% of trials published results in an accredited scientific journal and a further 10% in alternate form, such as a conference abstract or media release. Publication rates were higher for trials with a commercial sponsor (85%) compared with trials sponsored by a cooperative group (77%). Nearly 8% of trials in this study had not been registered on an international clinical trials register. Only 39% of unregistered trials had published results. Of the registered trials, those registered on ClinicalTrials.gov were more likely to be published (86%) compared with trials listed on ANZCTR (68%). Between 2009 and 2013 , 8% of trials registered on ClinicalTrials.gov , in our data set, were terminated; 70% of these trials published results. Conclusion: Although the rate at which clinical trial findings were published in Victoria was higher in this investigation compared with equivalent overseas data, trials registered on ClinicalTrials.gov were more likely to publish results than unregistered trials or trials registered on ANZCTR. This suggests a potential need for trial registration and publication guidelines in Australia, similar to that of the United States where the requirements and procedures for submitting registration and summary result information for clinical trials on ClinicalTrials.gov have been compulsory for the last decade.