In order to complete a systematic review a comprehensive literature search is done. Although, authors of systematic reviews are encouraged to search trial registries, more than 50% of published systematic reviews do not do this. It is also known that at least 50% of trials are never published, and the reasons for this have not been fully studied.
To survey authors of trials initiated in 2007, 2009 or 2011 in the Australian New Zealand Clinical Trials Register (ANZCTR), to determine if their trials have been completed and subsequently published, and, if not, determine reasons for non-publication.
The ANZCTR provided a list of randomised controlled trials (RCTs) registered in the years 2007, 2009 and 2011. We sent a 15-question survey to the scientific contact and primary investigator for each trial. We collated and summarised responses to the survey. We obtained ethical approval from the University of Auckland Human Participants Ethics Committee.
Of the 1886 registered trials, 569 investigators partially or fully completed the questionnaire (30%). A total of 89% of trials had been completed, 5% of trials were still ongoing and 6% of trials had been halted. For the trials that had been halted the following reasons were given: inability to recruit (57%); insufficient time (23%); and insufficient funding (26%). Of the 552 responses about publication, 70% claimed to have published their trials, while 136 (83%) of the unpublished trialists answered questions about why they had not published or submitted. The most common explanation (38%) for non-publication was that the process of writing and submission was still ongoing; other common explanations were lack of time (11%) and journal rejection (9%).
Of those who completed their trials, almost three-quarters had published. The majority of investigators who reported that their trials had not been published were still seeking publication. Significant non-response bias is likely to have affected these results, as those that had published their research were more likely to answer our questionnaire than those that had not.
Patient or healthcare consumer involvement:
Healthcare consumers participate altruistically in research to improve healthcare in the long-term. There is an expectation that the results of this research will be published. Failure to publish this research is a betrayal of the relationship between researchers and consumers.