Criteria

American College of Rheumatology (ACR)/European League Against Rheumatism (EULAR) collaborative initiative 2010 rheumatoid arthritis classification criteria[48]

Any patient with six or more points after the criteria have been applied is considered to have rheumatoid arthritis (RA). Before the criteria can be applied, patients need to have at least one joint with synovitis, and other reasons for it need to be ruled out.

Joint distribution

  • 1 large joint - 0 points

  • 2-10 large joints - 1 point

  • 1-3 small joints (large joints excluded) - 2 points

  • 4-10 small joints (large joints excluded) - 3 points

  • >10 joints (at least 1 small joint) - 5 points

Serology

  • Negative rheumatoid factor (RF) and negative anti-cyclic citrullinated peptide (anti-CCP) antibodies - 0 points

  • Low positive RF or anti-CCP antibodies (≤3 x upper normal limit) - 2 points

  • High positive RF or anti-CCP antibodies (>3 x upper normal limit) - 3 points

Symptom duration

  • <6 weeks - 0 points

  • ≥6 weeks - 1 point

Acute-phase reactants

  • Normal CRP and erythrocyte sedimentation rate (ESR) - 0 points

  • Abnormal CRP or ESR - 1 point

American Rheumatism Association 1987 revised criteria for the classification of rheumatoid arthritis[71]

For classification purposes, patients are said to have RA if they satisfy at least 4 of these 7 criteria (criteria 1-4 must have been present for ≥6 weeks):

  • Morning stiffness: lasting ≥1 hour before maximal improvement

  • Arthritis of three or more joint areas: simultaneously have had soft tissue swelling or fluid, observed by a physician. The 14 possible areas are right or left proximal interphalangeal (PIP), metacarpophalangeal (MCP), wrist, elbow, knee, ankle, and metatarsophalangeal (MTP) joints

  • Arthritis of hands: at least one swollen area in a wrist, MCP, or PIP

  • Symmetrical arthritis

  • Rheumatoid nodules: subcutaneous nodules over bony prominences or extensor surfaces or in juxta-articular regions observed by a physician

  • Serum rheumatoid factor

  • Radiographic changes: typical changes in posteroanterior hand and wrist radiographs; must include erosions or unequivocal bony decalcification localised in or most marked adjacent to the involved joints

EULAR definition of difficult-to-treat rheumatoid arthritis[85]

Developed for use in clinical practice and research, the definition of difficult-to-treat rheumatoid arthritis are based on the following three criteria:

  1. A patient being treated according to the EULAR recommendations who experiences treatment failure of two or more biological or targeted synthetic disease-modifying anti-rheumatic drugs (DMARDs) (with different mechanisms of action)* after failing conventional synthetic DMARD therapy (unless contraindicated)**.

  2. The patient will have signs suggestive of active/progressive disease, defined as one or more of the following:

    • At least moderate disease activity (according to validated composite measures including joint counts, for example, DAS28-ESR Score*** >3.2 or clinical disease activity index (CDAI) >10)

    • Signs (including acute phase reactants and imaging) and/or symptoms suggestive of active disease (joint related or other)

    • Inability to taper glucocorticoid treatment (below 7.5 mg/day prednisone or equivalent

    • Rapid radiographical progression (with or without signs of active disease)****

    • Well-controlled disease according to above standards, but still having RA symptoms that are causing a reduction in quality of life

  3. The management of signs and/or symptoms is perceived as problematic by the rheumatologist and/or patient.

All three criteria must be present in difficult-to-treat Rheumatoid Arthritis.

*Unless restricted by access to treatment due to socioeconomic factors.

**If conventional synthetic DMARD treatment is contraindicated, failure of ≥2 biological or targeted synthetic DMARDs with different mechanisms of action is sufficient.

***DAS28-ESR, disease activity score assessing 28 joints and erythrocyte sedimentation rate.

****Rapid radiographical progression: change in van der Heijde-modified Sharp score ≥5 points at 1 year.

ACR/EULAR remission criteria for Rheumatoid Arthritis 2022 revision[86][87]

To provide a definition of remission that is stringent but attainable for clinical trials, and for patient assessment in clinical practice.

Definition of remission in rheumatoid arthritis clinical trials:

At any time point, patient must satisfy all of the following:

Tender joint count ≤1*

Swollen joint count ≤1*

C-reactive protein ≤1 mg/dL

Patient Global Assessment ≤1 (on a 0-10 scale)**

OR

At any time point, the patient must have simplified disease activity (SDAI) ≤3.3***

Definition for rheumatoid arthritis in clinical practice:

Tender Joint Count 28 ≤1

Swollen Joint Count 28≤1

Patient Global Assessment ≤2

OR

CDAI ≤2.8****

*For swollen joint counts, a 28 joint count may miss active joints especially in the feet and ankles and it is preferable to include feet and ankles when evaluating remission.

**The following working and response categories should be used for global assessment: considering all of the ways your arthritis has affected you, how do you feel your arthritis is today? Verbal anchors for the response can range from ‘asymptomatic’ to severe ‘symptoms’.

***SDAI, simplified Disease Activity Index is defined as the simple sum of the tender joint count (28), swollen joint count (28), patient global assessment score (on a scale of 0-10), physician global assessment (on a scale of 0-10), and C-reactive protein (mg/dL).

****CDAI, Clinical Disease Activity Index, same as SDAI but without C-reactive protein.

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