Fig 1.
Procedure for data joining and publication search.
Table 1.
Examples of database entries and their ratings (AM: Aggregation method).
Table 2.
General descriptive information of the overall database and the manually inspected sample.
Table 3.
Pre-Registration, registration quality with 95% confidence intervals and article availability in the overall database and in the manually inspected sample depending on structural factors.
Table 4.
Summary of logistic regression models of Odds-Ratios for Pre-Registration with p-values in parentheses and 95% confidence intervals.
Table 5.
Mean quality ratings in Clinicaltrials.gov, DRKS, and other registries, grouped by study type (Int: Interventional, Obs: Observational).
Table 6.
Summary of linear regression models predicting mean percentage of attainable registration quality score over all criteria with P-Values in parentheses and 95% confidence intervals.
Fig 2.
Trends in registration quality over time separately for the different registries.
Table 7.
Number and percent of Pre-Registered studies depending on status as university of excellence and on presence of a coordinating center for clinical studies.
Trials that were registered between 2007 and 2013.
Table 8.
Number of studies for which articles could be found manually and a comparison of those articles to the references found on ClinicalTrials.gov, also as number of studies.
Fig 3.
Percentage of trials with published scientific articles in the manually inspected sample.
Table 9.
Summary of logistic regression models of Odds-Ratios for article availability with p-values in parentheses and 95% confidence intervals.