If you PMR or GCA (I have had both ) do yourself a big favor and look at the neurology and ophthalmology research literature suggesting that many if not most episodes of GCA are triggered by Varicella Zoster the virus that causes chickenpox and shingles.
I was lucky and became a patient of neurologists at the University of Colorado Anschutz Campus where I was started on antiviral therapy which immediately began my recovery . I have not had symptoms of PMR or GCA for 3 years.
I can almost guarantee that your rheumatologist will be negative . All I would suggest is that you try an inexpensive and safe antiviral , valcyclovir used for other similar viruses as well and available generically , in addition to "standard therapy" an see for yourself if it helps . Most of us are in the last decade or so of our lives and have little to lose and certainly do not have decades to" wait until we have more studies". SEE articles by Don Gilden MD and Maria Nagel MD in medical literature , just google them.
James E Young MD , mt USA