Rheumatoid arthritis

Last revised by Henry Knipe on 12 Jun 2024

Rheumatoid arthritis (RA) is a chronic autoimmune multisystemic inflammatory disease that affects many organs but predominantly attacks the synovial tissues and joints.

The pediatric condition, juvenile rheumatoid arthritis, is discussed separately.

The overall prevalence is 0.5-1% and the disease is 2-3 times more common in women 1. Onset is generally in adulthood, peaking in the 4th and 5th decades ref.

  • smoking (seropositive RA) 12

  • obesity ref

  • low socioeconomic status ref

The clinical features can be broadly categorized as articular and extra-articular. Generally, the onset of the condition may be insidious or abrupt, and early features commonly include tiredness, malaise, and generalized aches ref. Articular features generally develop prior to extra-articular features ref.

Articular features include a symmetrical deforming peripheral polyarthropathy that classically affects the fingers and hands, but also commonly involves the feet and can involve multiple other joints. The arthropathy has a classic inflammatory phenotype, with joint stiffness, reduced range of motion, reduce functionality, and a 'boggy' feel to palpation. For further details, please refer to musculoskeletal manifestations of rheumatoid arthritis.

Extra-articular features include ref:

Etiology is unknown but is probably multifactorial. It is generally considered that a genetic predisposition (e.g. HLA-DR B1 which is the most common allele of HLA-DR4 involved in rheumatoid arthritis) and an environmental trigger (e.g. Epstein-Barr virus postulated as a possible antigen, but not proven) lead to an autoimmune response that is directed against synovial structures and other organs ref.

Activation and accumulation of CD4 T cells in the synovium start a cascade of inflammatory responses which result in ref:

  • activation of the macrophages and synovial cells and production of cytokines such as IL4 and TNF, which in turn cause proliferation of the synovial cells and increase the production of destructive enzymes such as elastase and collagenase by macrophages

  • activating B cell lymphocytes to produce various antibodies including rheumatoid factor (RF-IgM antibodies against Fc portion of the IgG) which makes immune complexes that deposit in different tissues and contribute to further injury 

  • directly activate endothelial cells via increased production of VCAM1, which increases the adhesion and accumulation of inflammatory cells

  • producing RANKL which in turn activate osteoclasts causing subchondral bone destruction 

The inflammatory response leads to pannus formation. Pannus is an edematous thickened hyperplastic synovium infiltrated by lymphocytes T and B, plasmocytes, macrophages, and osteoclasts. Pannus will gradually erode bare areas initially, followed by the articular cartilage. It causes fibrous ankylosis which eventually ossifies 2,3.

Diagnosis is based on a combination of clinical, radiographic, and serological criteria. The 2010 ACR - EULAR classification criteria for Rheumatoid Arthritis 4 has a maximal score of 10 and requires a score of >6 for a diagnosis of rheumatoid arthritis to be made:

  • joint involvement

    • 0: 1 large joint

    • 1: 2-10 large joints

    • 2: 1-3 small joints (with or without the involvement of large joints)

    • 3: 4-10 small joints (with or without the involvement of large joints)

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

  • serology

    • 0: negative RF and negative anti-CCP

    • 2: low-positive RF or low-positive anti-CCP

    • 3: high-positive RF or high-positive anti-CCP

  • acute phase reactants

    • 0: normal CRP and normal ESR

    • 1: abnormal CRP and abnormal ESR

  • duration of symptoms

    • 0: <6 weeks

    • 1: >6 weeks

There are several serological markers for rheumatoid arthritis ref:

  • rheumatoid factor (RF): is an IgM antibody against FC portion of the IgG antibodies, and is a traditional marker but is non-specific; associated with several autoimmune and chronic infectious diseases

  • anti-cyclic citrullinated peptide (anti-CCP)/anti-citrullinated plasma antibody (ACPA): it is more than 80% sensitive and more than 95% specific

  • elevated CRP and/or ESR

Musculoskeletal manifestations are the earliest and dominant features of rheumatoid arthritis ref.

For further details, please refer to musculoskeletal manifestations of rheumatoid arthritis.

Pulmonary rheumatoid disease may involve the airway, interstitium, and/or pleura; a full description is available in respiratory manifestations of rheumatoid arthritis ref.

Splenomegaly may be seen as part of Felty syndrome, usually in long-standing rheumatoid arthritis ref.

Treatment of rheumatoid arthritis is aimed at improving the symptoms and slowing disease progression. Medications used in treatment include:

  • non-steroidal anti-inflammatory drugs (NSAIDs)

  • disease-modifying anti-rheumatic drugs (DMARDs)

    • conventional synthetic DMARDs (csDMARDs): e.g. methotrexate, leflunomide, prednisolone

    • biological DMARDs (bDMARDs): e.g. TNF-α inhibitors (e.g. infliximab), tocilizumab, abatacept, rituxumab

    • targeted synthetic DMARDs (tsDMARDs): e.g. tofacitinib

The disease carries a significant burden of disability. There is also a reduction in life expectancy, with excess mortality usually related to its non-articular manifestations 5,6.

Rheumatoid arthritis was a term first coined by British physician Sir Alfred Baring Garrod (1819-1907) in 1859 11.

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