Your PMR does sound very mild. Thats what makes this disease so hard for one to say this works when it doesnt work for someone else. I believe just from being on this site and a facebook site that my 6 months was fairly mild as well. I would almost question whether PMR was the correct diagnosis at 4mg. Prednisone can be used on almost any inflammatory disease or reaction. In any case, if it worked thats great. I started at 20mg. Pain was gone in 4 hours. Within the first 2 weeks you can play with the dosage to get to your lowest possible dose. After about 2 weeks the prednisone is supplying your cortisone and your body shuts down production. I went to 15mg after 2 days. No Pain. 2 days later I dropped to 10mg. No pain. 2 days later I dropped to 5mg and had trouble with movement. I went back to 10mg and no pain. I would try to taper about once a month to 5mg and was unable to taper. On the 5th month I tapered to 5mg and only slight pain. I went about 2 weeks on 5mg then tapered to 2.5mg. I had some slight discomfort but manageable. After 2 weeks I went to zero. I had some slight discomfort that an alleve would fix for 3 to 4 months. It took almost a year to feel like it was gone. To answer your question, I went by how well I responded to lower the dose. You can check sed rate and ESR but those tests were not elevated for me. The testing was not effective. I would continually try to reduce my prednisone. My opinion is you should move from 4mg to 3mg? see what happens and keep trying to reduce. Move as quickly as your body allows. The prednisone makes you feel wonderful but the long term use is pretty destructive.