Barriers towards the publication of academic drug trials. Follow-up of trials approved by the Danish Medicines Agency

To characterize and quantify barriers towards the publication of academic drug trials. We identified academic drug trials approved during a 3-year period (2004-2007) by the Danish Medicines Agency. We conducted a survey among the trial sponsors to describe the rates of initiation, completion, and publication, and the reasons for the failure to reach each of these milestones. Information on size and methodological characteristics of the trials was extracted from the EudraCT database, a prospective register of all approved clinical drug trials submitted to European medicines agencies since 2004. A total of 181 academic drug trials were eligible for inclusion, 139 of which participated in our survey (response rate: 77%). Follow-up time ranged from 5.1 to 7.9 years. Most trials were randomized controlled trials (73%, 95% CI 65-81%). Initiation and completion rates were 92% (95% CI: 88-97%) and 93% (95% CI: 89-97%) respectively. The publication rate of completed trials was 73% (95% CI: 62-79%). RCTs were published faster than non-RCTs (quartile time to publication 2.9 vs. 3.1 years, p = 0.0412). Many academic drug trials are left unpublished. Main barriers towards publication were related to the process from completion to publication. Hence, there is much to gain by facilitating the process from analysis to publication. Research institutions and funders should actively influence this process, e.g. by requiring the publication of trial results within a given time after completion.