ACR Score: What Does an ACR Score Measure?

The ACR scoring system, named after the American College of Rheumatology, helps physicians to measure the amount of improvement in their patients’ rheumatoid arthritis after being treated with various medications. In other words, the ACR score measures the efficacy of certain treatments for rheumatoid arthritis. The initial ACR system developed is the ACR20, which measures a twenty percent improvement in the patient’s reported pain scale and swelling in designated joints. Later on, ACR50 and ACR70 were also adopted to respectively indicate a fifty or seventy percent improvement in patients’ rheumatoid arthritis symptoms.

Interpreting the ACR Score

ACR scores take into account a variety of factors to create a score assessing the amount of improvement a patient’s rheumatoid arthritis has made after treatment.  ACR criteria also assess and establish improvement in tender and painful joint counts, as well as improvement in three of five of the following parameters:

• Inflammation – Laboratory tests, either measuring the sedimentation rate or C-reactive proteins, determine the amount of inflammation in the joints.
• Patient assessment – The patient describes and determines their own assessment of their progress.
• Physician assessment – The physician describes and determines the patient’s progress.
• Pain scale – How much the pain the patient feels in his or her joints on a daily base
• Disability/functionality questionnaire – How much the patient is able to use his or her joints easily to complete daily activities

If a patient were to receive a score of ACR 20, that means that that patient has improved their tender and painful joint counts by 20 percent, as well as made a 20 percent improvement in three of the five above parameters.

Usage of ACR Scores

ACR scores are most often used in the context of clinical trials rather than between physicians and patients. The most prominent purpose of the score was to standardize measures of improvement in clinical trials so that different clinical trials of treatments and medications would be more easily compared and evaluated. The US Food and Drug Administration has also recognized the ACR20 as a preferred method of evaluating the efficacy of a new drug in improving the signs, symptoms, and complications of rheumatoid arthritis.