Reporting of retrospective registration in clinical trial publications: a cross-sectional study of German trials

Abstract

ObjectiveProspective registration has been widely implemented and accepted as a best practice in clinical research, but retrospective registration is still commonly found. We assessed to what extent retrospective registration is reported transparently in journal publications and investigated factors associated with transparent reporting.DesignWe used a dataset of trials registered in ClinicalTrials.gov or Deutsches Register Klinischer Studien, with a German University Medical Center as the lead centre, completed in 2009–2017, and with a corresponding peer-reviewed results publication. We extracted all registration statements from results publications of retrospectively registered trials and assessed whether they mention or justify the retrospective registration. We analysed associations of retrospective registration and reporting thereof with registration number reporting, International Committee of Medical Journal Editors (ICMJE) membership/-following and industry sponsorship using χ2or Fisher exact test.ResultsIn the dataset of 1927 trials with a corresponding results publication, 956 (53.7%) were retrospectively registered. Of those, 2.2% (21) explicitly report the retrospective registration in the abstract and 3.5% (33) in the full text. In 2.1% (20) of publications, authors provide an explanation for the retrospective registration in the full text. Registration numbers were significantly underreported in abstracts of retrospectively registered trials compared with prospectively registered trials. Publications in ICMJE member journals did not have statistically significantly higher rates of both prospective registration and disclosure of retrospective registration, and publications in journals claiming to follow ICMJE recommendations showed statistically significantly lower rates compared with non-ICMJE-following journals. Industry sponsorship of trials was significantly associated with higher rates of prospective registration, but not with transparent registration reporting.ConclusionsContrary to ICMJE guidance, retrospective registration is disclosed and explained only in a small number of retrospectively registered studies. Disclosure of the retrospective nature of the registration would require a brief statement in the manuscript and could be easily implemented by journals.

Prospective Registration of Trials: Where we are, why, and how we could get better

“…First, we did not review the full text of RCTs to identify the reasons for retrospective or non-registration. However, we consider this a minor concern given that a recent study showed that only 3.5% of RCTs report the reasons for retrospective registration in the published manuscript 35 . Second, there is a risk of selection bias due to the low proportion of participants in our survey that intended to determine the reasons for non-prospective registration, as respondents and non-respondents might have different profiles.…”

Trials that turn from retrospectively registered to prospectively registered: a cohort study of “retroactively prospective” clinical trial registration using history data

“…Previous research has already dealt with the extent of prospective or retrospective registration of clinical trials [ 11 , 12 ], finding that between one half and two thirds of the trials are registered retrospectively. Two publications have also dealt with changes to start dates [ 13 , 14 ], finding that between 7 and 14% have changes to the start date.…”

Response to Letter to Editor

“…In the data set of 1927 trials with a corresponding results publication, 956 (53.7%) were retrospectively registered. Publications in the International Committe of Medical Journal Editors (ICMJE) member journals did not have statistically significantly higher rates of both prospective registration and disclosure of retrospective registration, and publications in journals claiming to follow ICMJE recommendations showed statistically significantly lower rates compared with non–ICMJE-following journals 2 …”

“…Publications in the International Committe of Medical Journal Editors (ICMJE) member journals did not have statistically significantly higher rates of both prospective registration and disclosure of retrospective registration, and publications in journals claiming to follow ICMJE recommendations showed statistically significantly lower rates compared with non-ICMJE-following journals. 2 The World Health Organization stated that retrospective in a short time frame from enrollment is preferable and acceptable compared with no registration at all. 3 It is important to allow for retrospective trial registration of studies that have not been prospectively registered to prevent the nonpublication of potentially valuable research for which human participants have given up their time and exposed themselves to risk.…”