Exactly this kind of registration is mandatory for clinical trials under the Declaration of Helsinki and in US and EU law, but it's still poorly enforced.
If this issue matters to you, I would encourage you to support the AllTrials campaign; they have done stellar work in exposing publication bias.
If this issue matters to you, I would encourage you to support the AllTrials campaign; they have done stellar work in exposing publication bias.
http://www.alltrials.net/