Via Yalda Afshar, a 2005 paper by Hans-Hermann Dubben and Hans-Peter Beck-Bornholdt:

Publication bias is a well known phenomenon in clinical literature, in which positive results have a better chance of being published, are published earlier, and are published in journals with higher impact factors. Conclusions exclusively based on published studies, therefore, can be misleading. Selective under-reporting of research might be more widespread and more likely to have adverse consequences for patients than publication of deliberately falsified data. We investigated whether there is preferential publication of positive papers on publication bias.

They conclude, “We found no evidence of publication bias in reports on publication bias.” But of course that’s the sort of finding regarding publication bias of findings on publication bias that you’d expect would get published. What we really need is a careful meta-analysis to estimate the level of publication bias in studies of publication bias of studies of publication bias.