An American College of Rheumatology (ACR) score is a scale used to measure the improvement in arthritis symptoms. ACR scores are used in clinical trials and for Food and Drug Administration approval for new medications.

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An American College of Rheumatology (ACR) score is an important way to evaluate the effectiveness of certain medications used to treat arthritis.

ACR scores are most often used to assess rheumatoid arthritis (RA); however, in the past, the ACR score was also used to monitor other forms of arthritis, including psoriatic arthritis (PsA).

Currently, the ACR 20/50/70 screening can be used to assess PsA. The ACR 20/50/70 screening, however, only measures peripheral joint disease of the hands, feet, knees, etc., and it doesn’t assess the axial spine.

There are now other, more specialized tests used to assess medications to treat PsA, but there’s no consensus on the best test to use when assessing PsA. The test used will depend on the purpose of the assessment and how it will be used.

ACR scores are a way for doctors to measure the improvement people with RA have after taking medication. The test was created to help standardize the assessment and evaluation of the effectiveness of treatment.

Today, these scores are used in clinical trials and in the Food and Drug Administration (FDA) approval process as a way to record how effective a medication is at reducing symptoms.

The ACR50 and ACR70 are the most commonly used ACR tests. They measure a 50% improvement and 70% improvement in RA symptoms, respectively, before starting treatment and after being on a treatment medication for a specific period of time.

The ACR20, which measures a 20% improvement in symptoms, may also be used, but it’s not used as often because new products need to meet a higher bar to earn FDA approval.

Since PsA is a very complex disease, a different tool is needed to measure disease activity. One of the new tests, the psoriatic arthritis response criteria (PsARC), was created to measure changes and evaluate the efficiency of medications. However, there are many other options for assessing the effectiveness of PsA treatment and symptoms.

Other PsA measures include:

  • 28-joint disease activity score (DAS28)
  • 76/78-swollen and tender joint counts (SJC76/TJC78)
  • 66/68-swollen and tender joint counts (SJC66/TJC68)
  • Leeds enthesitis index (LEI)
  • Spondylarthritis Research Consortium of Canada (SPARCC) index
  • ankylosing spondylitis disease activity (ASDAI)
  • dactylitis severity score (DSS)
  • Bath ankylosing spondylitis disease activity index (BASDAI)
  • Bath ankylosing spondylitis function index (BASFI)
  • ankylosing spondylitis quality of life index (ASQoL)
  • psoriasis area and severity index (PASI)
  • minimal disease activity (MDA)
  • GRAPPA composite exercise (GRACE) score
  • PsA disease activity score (PASDAS)
  • composite psoriatic disease activity index (CPDAI)
  • disease activity in PsA (DAPSA)
  • nail psoriasis severity index (NPSI)
  • modified nail psoriasis severity index (mNAPSI)
  • psoriasis nail severity score (PNSS)

There are typically four components on the PsARC score that a doctor uses to assess if there are any improvements to an individual’s condition. These components include:

  • assessment of joint tenderness using 68 joint counts (counting pain in 68 joints)
  • assessment of joint swelling using 66 joint counts (counting pain in 66 joints)
  • the person’s opinion of their global health
  • the physician’s global assessment of the person’s health

According to research published in 2014, one main problem with the PsARC is that parts of the test are too subjective and dependent on judgments that can vary based on who’s administering the test.

Due to concerns about the ACR score not capturing joint counts commonly impacted in PsA, the PsARC was introduced.

In order to assess and monitor PsA, the ACR score is altered to use a 68/66 joint count, which includes ankle and foot counts in determining the disease activity score (DAS) to show if the PsA is active or in remission.

In other words, 66 joints are assessed for tenderness, and 68 joints are assessed for swelling. The joint count is the sum total of the tender and swollen joints. The hip joints are only evaluated for tenderness and not swelling, which is where the “66 count” comes from.

The FDA determines whether a company or organization’s product is safe for public use or consumption reviewing medications for safety, quality, and effectiveness. The PsARC is one FDA-approved instrument that researchers may use during clinical trials.

The PsARC criteria are used to measure individuals who report a 50% or 70% improvement in tender and swollen joints when assessing the effectiveness of medications in clinical trials for medications that may be used to treat PsA.

However, there’s no one preferred measure when assessing treatments for PsA. The measure depends on how the new drug being assessed works and what measures indicate successful treatment.

In 2016, the Outcome Measures in Rheumatology (OMERACT) determined that the following criteria should be considered when assessing potential PsA treatments:

  • musculoskeletal disease activity
  • skin disease activity
  • fatigue
  • pain
  • global assessment
  • physical function
  • health-related quality of life
  • inflammation throughout the entire body (systemic inflammation)

OMERACT also noted that the economic cost and emotional well-being of participants, as well as independence, sleep, stiffness, and treatment burden, should be considered.

What are the types of psoriatic arthritis?

There are several types of PsA, including:

How is the severity of psoriatic arthritis measured?

The severity of PsA varies for each individual. Typically it can be mild, moderate, or severe, and the level is dependent on the number of joints that are affected.

In mild forms of PsA, four or fewer joints are affected. In moderate PsA, four or more joints are affected, and the person’s physical and mental well-being may be impacted.

In severe PsA, five or more joints throughout the body are affected. Quality of life may be severely impacted.

A physical exam by a doctor can help with a diagnosis. The PsARC exam is also used to assess the number of joints affected, the person’s fatigue levels, inflammation, and more.

The goal of treatment is remission or minimal disease activity (MDA). There are other measures that are composite measures of MDA.

If you have PsA, it’s important to monitor the condition, including any improvements and setbacks.

The ACR score is one way to monitor PsA. Although the ACR score is traditionally used to measure disease activity in people living with RA, it’s been altered for those with PsA.

The PsARC looks at four components: the 68/66 joint counts to measure joint tenderness and swelling, the person’s opinion of their overall health, the physician’s global assessment, and inflammation.

While a doctor may make an assessment, the ACR score and PsARC are used most often as assessments in PsA clinical trials.

Outcome measures are still evolving, but the current measures have allowed a number of therapeutics to be approved for use in the treatment of PsA.