No ... only anecdotal accounts of what I read on forums like this. I don't have any personal experience with hydroxychloroquine but many people say it works for them.

I find studies like the following interesting.
https://pubmed.ncbi.nlm.nih.gov/27843369/
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Except for being diagnosed with PMR ... I don't know how anyone knows it is really PMR. It would be impossible to exclude all of the other conditions that mimic PMR before diagnosing PMR. A rapid response to Prednisone isn't conclusive evidence because many autoimmune disorders respond rapidly to Prednisone.

Most of the time it seems likely that there might be other conditions in play and rarely do people have an isolated case of PMR. I have multiple autoimmune conditions myself in addition to being diagnosed with PMR. I'm happy that Actemra works for me and I was able to discontinue prednisone.

Anything that works for someone else makes me happy because 12 years on prednisone wasn't good for me. If prednisone works and doesn't cause too many ill effects for people, that makes me happy too.