Transparency and completeness of reporting in study registries - a comparative study

Tags: Oral
Blümle A1, Möhler R1, Kunzweiler K1
1Institute for Evidence in Medicine (for Cochrane Germany Foundation)

Background: Information from medical research is essential for both patients and health professionals to make informed decisions about health issues. Study results should be made publicly available in a timely manner. Information about planned or ongoing studies is also valuable for further research and patients. Prospective study registration, providing a minimum data set, and publication of results is highly recommended and has become mandatory in several countries. In most study registries additional study information can be linked to the study record; in ClinicalTrials.gov results can also be added in tabular form.

Objectives: In a quasi-experimental study we investigated the transparency in clinical research measured as the availability of detailed study reports via study registries.

Methods: We randomly selected studies from ClinicalTrials.gov and the German Clinical Trials Register (DRKS). We also included trials funded by the German Research Foundation and the German Federal Ministry of Education and Research.

We investigated predefined cohorts: 1) investigator-initiated-trials, 2) industry-sponsored-trials, conducted a) internationally and b) nationally, whether A) a study protocol or method paper was linked to the register entry; or B) study results were available in tabular form or via link. We will determine and compare study duration, time to publication and influencing study factors (e.g. sample size, study phase, intervention type).

Results: We identified 691 studies. Reports on methods were available for 95 (13.7%) studies and on results for 271 (39%), with 417 corresponding articles overall (median 1, range 1 to 9); 115 (42.4%) also had tabular results, 156 (57.6%) only a linked publication. Of the 627 studies derived from ClinicalTrials.gov, 237 (37.8%) had tabular results; 25/64 (39.0%) from the DRKS links. Analysis of time to publication and the influencing factors is in progress and will be presented at the Colloquium.

Conclusions: Study registration and publication of results is required from several organisations (e.g. government, funding bodies, journals), but in registries often basic data only are reported. Stronger rules are required to ensure that all essential information is available.

Patient or healthcare consumer involvement: Patients were not directly involved in this methodological research project.