(1) To assess endorsement of trial registration in author instructions of urology-related journals and (2) to assess whether randomised controlled trials (RCTs) in the field of urology were effectively registered.
Cross-sectional study of author instructions and published trials.
Journals publishing in the field of urology.
First, the authors analysed author instructions of 55 urology-related journals indexed in ‘Journal Citation Reports 2009’ (12/2010). The authors divided these journals in two groups: those requiring and those not mentioning trial registration as a precondition for publication. Second, the authors chose the five journals with the highest impact factor (IF) from each group.
MEDLINE search to identify RCTs published in these 10 journals in 2009 (01/2011); search of the clinical trials meta-search interface of WHO (International Clinical Trials Registry Platform) for RCTs that lacked information about registration (01–03/2011). Two authors independently assessed the information.
Proportion of journals providing advice about trial registration and proportion of trials registered.
Of 55 journals analysed, 26 (47.3%) provided some editorial advice about trial registration. Journals with higher IFs were more likely to mention trial registration explicitly (p=0.015). Of 106 RCTs published in 2009, 63 were registered (59.4%) with a tendency to an increase after 2005 (83.3%, p=0.035). 71.4% (30/42) of the RCTs that were published in journals mentioning and requiring registration, and 51.6% (33/64) of the RCTs that were published in journals that did not mention trial registration explicitly were registered. This difference was statistically significant (p=0.04).
The existence of a statement about trial registration in author instructions resulted in a higher proportion of registered RCTs in those journals. Journals with higher IFs were more likely to mention trial registration.
Trial registration can increase scientific transparency, but its implementation in specialty fields such as urology is unclear.
To assess the endorsement of trial registration in the author instructions of urology-related journals.
To assess whether randomised controlled trials in the field were effectively registered.
A statement of trial registration in author instructions resulted in a higher proportion of registered randomised controlled trials.
Journals with high impact factors were more likely to mention trial registration.
We suggest, though, that ensuring trial registration is not the responsibility only of the editors. Medical scientists should realise that trial registration is necessary to contribute to transparency in research.
Strength and limitations of this study
Two authors independently assessed information regarding editorial advice about trial registration and identified the randomised controlled trials.
Potential bias occurred if registered randomised controlled trials were reported without giving a registration number and we could not identify them in the meta-search interface of WHO (International Clinical Trials Registry Platform).
Results might not be representative of the uro-nephrological field as a whole and reported figures may overestimate compliance with trial registration.