Dear Richard: You write: "A study of the 49 most highly cited papers on medical interventions published in high profile journals between 1990 and 2004 showed that a quarter of the randomised trials and five of six non-randomised studies had been contradicted or found to be exaggerated by 2005. (2) We know too that "positive" drug trials are much more likely to be published than "negative" trials, although we don't know how much this is the result of conscious manipulation by authors and sponsors and how much the result of "the winner's curse." (3-5). Most scientists read a few high profile journals — and so are fed a systematically distorted view of the evidence. "
The last sentence does not follow, because "high profile" journals such as Nature, Science and Cell do not publish clinical trials, the studies to which you refer in the previous sentences.
Best wishes
Maxine (Clarke, an editor at Nature).