Non-publication and delayed publication of randomized trials on vaccines: survey

Abstract

Objective To evaluate the extent of non-publication or delayed publication of registered randomized trials on vaccines, and to investigate potential determinants of delay to publication. Design Survey.Data sources Trials registry websites, Scopus, PubMed, Google. Main outcome measures Publication status of trial results and time from completion to publication in peer reviewed journals. Study selectionData synthesis Cox proportional hazards regression was used to evaluate potential predictors of publication delay. ResultsWe analysed 384 trials (85% sponsored by industry). Of 355 trials (404 758 participants) that were completed, 176 (n=151 379) had been published in peer reviewed journals. Another 42 trials (total sample 62 765) remained unpublished but reported results in ClinicalTrials.gov. The proportion of trials published 12, 24, 36, and 48 months after completion was 12%, 29%, 53%, and 73%, respectively. Including results posted in ClinicalTrials.gov, 48 months after study completion results were available for 82% of the trials and 90% of the participants. Delay to publication between non-industry and industry sponsored trials did not differ, but non-industry sponsored trials were 4.42-fold (P=0.008) more likely to report negative or mixed findings. Negative results were reported by only 2% of the published trials.Conclusions Most vaccine trials are published eventually or the results posted in ClinicalTrials.gov, but delays to publication of several years are common. Actions should focus on the timely dissemination of data from vaccine trials to the public.

Conceptual frameworks and key dimensions to support coverage decisions for vaccines

“…Over the past decade, several randomised controlled trials evaluating the safety or the efficacy of new vaccines have been completed [1]. One approved by drug regulatory agencies, some of these vaccines, such as those for human papilloma virus and H1N1 influenza A, have been introduced into low, middle, and highincome countries.…”

The ethical problem of randomization

“…From the ethical point of view, it seems particularly relevant to pay attention to the sponsorship of the studies, conflict of interest disclosure, authorship and accountability of reporting, completeness of reporting results, even in case of ''negative'' studies [32,33]. Sponsorship of drug and device studies by the manufacturing company leads to more favorable results and conclusions than sponsorship by other sources [34].…”

Clinical trials: what a waste

“…This work adds to several other empirical evaluations showing that evidence from randomized controlled trials is wasted at multiple stages from conception to publication and beyond. [2][3][4][5][6][7][8][9][10][11][12] Many trials are entirely lost, as they are not even registered. Substantial diversity probably exists across specialties, countries, and settings.…”

“…The 34% non-publication rate reported by Chapman et al is among the more conservative estimates from studies assessing the publication rate of registered trials. [4][5][6][7] It is also conservative compared with another recent study of the non-publication rate (44%) of surgical trials approved by six ethics committees. 8 Paradoxically, published trials may be the weakest link in the chain of lost and distorted evidence.…”