I have been fighting osteoarthritis since diagnosis in knees and lumbar back in 1998. in 2017 was also diagnosed with ra. can having long term oa led to ra?

No. OA does not cause RA. While both affect joints, the underlying disease process and treatments are different. It would be prudent to consult a rheumatologist.

Osteoarthritis is a degenerative condition in which cartilage wears down and causes joint pain with activity. Rheumatoid arthritis is an inflammatory disease in which the immune system makes a mistake and attacks the body itself. The joint lining becomes inflamed and that causes joint pain, stiffness, and swelling.