• Epidemiology

In September 2009, the European Centre for Ecotoxicology and Toxicology of Chemical (ECETOC) held a workshop to discuss how the transparency of the design, conduct and reporting of observational studies could be improved.1 The main ‘solution’ discussed at the workshop was to increase the registration of observational studies, together with their a priori protocols (and any subsequent changes) in a recognised international database. Benefits of registration discussed at the workshop included increased transparency of design and conduct, the ability to distinguish hypothesis driven from exploratory analyses, improved peer review and ethical processes, reduction in publication bias through knowledge of the total body of research as opposed to only that that reaches the peer reviewed literature, and avoidance of duplication of effort.

So why are observational studies not registered as a matter of course? Clinical trial registration is now required under US law,2 the Declaration of Helsinki 3 and the International Committee of Medical Journal Editors (ICMJE).4 Has registration worked for clinical trials in regard to the benefits outlined above? It appears not entirely. Several scandals drew attention to the selective suppression of trial data, for example, in the use of selective serotonin reuptake inhibitors to treat depression in children where published data suggested a favourable risk–benefit profile, but the addition of unpublished data suggested risks could outweigh the benefits.5 One wonders how many inappropriate decisions have been made based on incomplete evaluation of epidemiological studies. Although one might argue that any damage cannot be as serious as that relating to clinical trials, the uses of epidemiological studies include making regulatory decisions on the setting of standards and limits, and the prioritisation of practical risk-reduction measures.

Following the clinical trial furore, several pharmaceutical companies began to set up their own registries which …