ACR 20- defines 20% improvement in swollen & tender joints of Rheumatoid arthritis. This is being used as a major criteria (defined by American College of Rheumatology) for assessing the improvement in patients with Rheumatoid arthritis.

ACR 50 -defines 50% improvement in swollen & tender joints of Rheumatoid arthritis.

ACR 70- defines 70% improvement in swollen & tender joints of Rheumatoid arthritis.