Trial registration and time to publication in a retrospective cohort of publicly funded randomised controlled trials in New Zealand 1999-2017.

objectivesTo determine how quickly randomised controlled trials funded by the Health Research Council of New Zealand (HRC) were registered and published, and whether time to publication differed by trial result.

designWe created a retrospective cohort of trials offered funding from 1999 to 2017 by seeking lists of candidate studies using the Official Information Act 1982. These lists were supplemented by searching the HRC's online research repository and an open-access database on Figshare. One investigator searched for trial registrations and for dissemination using electronic databases, university websites and ResearchGate. One investigator extracted data from the obtained studies and a second investigator independently corroborated the data entry from a 10% random sample.

resultsWe identified 258 trials that were offered funding, 252 trials were conducted and 229 (90.9%) were registered, 179 prospectively by the date of the final search (24 March 2022). Overall, 236 trials were completed by the date of the last search and in 209 (88.6%) trials the results had been disseminated, 200 (84.7%) of which were by journal publication. We obtained the results for 214 trials, 91 (42.5%) of which were positive, 120 (56.1%) of which were null and 3 (1.4%) of which were negative. Median time to publication was 22.7 months for positive trials and 21.5 months for combined null or negative trials (log rank test p=0.83). Median time since trial completion in the trials that had not been published was 43.6 months (IQR 17.1-108.2 months).

conclusionsBetween 1999 and 2017, almost 9 out of every 10 HRC-funded trials had been registered and a similar proportion of completed trials had been published with no difference in time to publication based on type of result. However, only a slim majority of trials had published within the 2-year time frame set by the WHO.