These criteria were developed by the American College of Rheumatology in 1988 and are still used to diagnose rheumatoid arthritis. Of these seven criteria, four are needed for a diagnosis. Criteria 1 through 4 must have been present for at least 6 weeks.¹

1. Morning stiffness lasting at least 1 hour before major improvement
2. Arthritis in three or more of the following joint areas on either side of the body: middle joint of the fingers, the knuckles (the largest joint that connects each finger to the rest of the hand), wrist, elbow, knee, or ankle or the joint between the toes and the foot (the joint at the base of the toe, closest to the foot)
3. Arthritis in the hand joints: specifically in the wrist, the knuckles, or the middle joint of the fingers
4. Joint swelling of the same joint on both sides of the body (symmetrical) or joint swelling on both sides of the body (but not necessarily the same joint) affecting the middle joint of the fingers, the knuckles, and/or the joint between the toes and the foot
5. Bumps (nodules) that develop under the skin over areas where bones protrude or near joints
6. Positive RF (rheumatoid factor) test
7. X-ray changes that show decalcified (more porous) bone or uneven patches of bone erosion (osteoporosis) around only the joints affected by rheumatoid arthritis. Thinning bones throughout the body (osteoporosis) unrelated to rheumatoid joints do not qualify.