• research, methods

The case for trial registration was first advanced almost two decades ago.1 Clinicians need to have access to the entire evidence base when they make judgements about whether treatments are effective. If researchers can undertake trials and then bury unfavourable results, then clinicians will be acting on misleading information and may harm their patients. There is evidence that trials with negative outcomes are less likely to be published, which could lead to overestimation of treatment effects in meta-analyses.2 This ‘publication bias’ is not only due to authors failing to submit negative trials for publication, but journals preferentially …