How often do patients with rheumatoid arthritis which had not been diagnosed show up in your pain clinics?

About once a week: In my rheumatology practice, i see about 15 new patients a week. I see about 3-4 new RA patients a month.

Not very common: Anecdotally, it is very rare. I've had more patients with chronic pain come in with seronegative spondyloarthropathy. In one case, i kept telling a patient i thought she had psoriatic arthritis but her doc kept saying she didn't until derm said nail problems were psoriasis. She even had family history of psoriasis.

For a generalist: of course everyone has pain. 10% of patients are primarily for pain but take 10x the number of visits of a patient without active problems. Of pain patients, back or neck disk disease number one by a wide margin. About 5%... but new diagnosis is about 1 a year.