There is not good evidence that peer review improves quality and there is perhaps some to the contrary (many predatory journals are peer reviewed). The arxiv (unreviewed) is among the most reliable sources available.

Independently replicated. Reviewed says pretty much nothing.

I think it's a bit different considering the goal was a teaching tool of well recognised conditions

>all or almost all were cases of very well recognized conditions [...] where a single case report would not generate any interest or ever be cited.

That is an ironic proviso given that the article clearly states

"The peer-reviewed articles don’t state anywhere the cases described are fictional."

Peer review by peers who are trained by non-replicable science is not helpful...

Doesn't sound like these works were "full" articles, but rather something more like short review articles.

out of context that makes sense...but in the context of a case report how do you implement that? The patients have privacy rights and the authors/doctors have a responsibliity to protect them. That doesn't justify this but it does force a conversation about what 'every single data point' means. Does it mean the patient's real name and social security number? their complete medical chart?

Case reports are descriptive not determinative and should be treated as such by other scholars. They are 'I saw this' not 'this is generalizably true'. They can (and often are) replicated or countered but they are not per se research as you are thinking about it. Whether it is fictitious or not, other scholars should be cautious in citing them as proof/evidence in papers that fit into the 'research' mold.

The article is about case reports, not about empirical studies. Putting a fake case report on GitHub wouldn't make it any less fake.

Since it was for teaching I expect the case studies were always showing typical features of real cases, so there's nothing in the case vignette itself to give it away unless the author picks a funny name or something like that.

Rather it would be the entire form of these short highlight articles that would make you keep searching for a proper citation, unless you're lazy or pressed for time.

Yeah, they seem to have been quite sloppy with these vignettes.

Thought note that in the situation of the mislabeled real case, the formal solution is could be a retraction of the entire highlight article since it is against the (poorly implemented) policy to have a real case study.

Don't know how patient consent for being used in a case study works, did this author get a perpetual license, did they just copy something from another article they wrote, or from an article someone else wrote?