I'm in the UK and thankfully I had a doctor who has experience in PMR diagnosis. But initially she was pretty certain but would not prescribe anything until blood tests were done and analysed. So for me that was 3 days of suffering with it and then the diagnosis was confirmed... In fairness there does not appear to be a test that says... Yes you have PMR.. In theory this could be something else as the symptoms are related to various other health issues but in reality how the process starts and how it doesn't bother smaller joints I am led to believe all signs point to PMR. Also it appears that the medication is helping so that again makes me feel like I have the correct diagnosis.