The name is derived from the Greek rheumatos meaning "flowing", the suffix -oid meaning "in the shape of", arthr meaning "joint" and the suffix -itis, a "condition involving inflammation".

Rheumatoid arthritis is a chronic, inflammatory, multisystem, autoimmune disorder. It commonly affects the joints in a polyarticular manner. The symptoms that distinguish rheumatoid arthritis from other forms of arthritis are inflammation and soft-tissue swelling of many joints at the same time (polyarthritis). The joints are usually affected initially asymmetrically and then in a symmetrical fashion as the disease progresses. The pain generally improves with use of the affected joints, and there is usually stiffness of all joints in the morning that lasts over 1 hour. Thus, the pain of rheumatoid arthritis is usually worse in the morning compared to the classic pain of osteoarthritis where the pain worsens over the day as the joints are used.

As the pathology progresses the inflammatory activity leads to erosion and destruction of the joint surface, which impairs their range of movement and leads to deformity. The fingers are typically deviated towards the little finger (ulnar deviation) and can assume unnatural shapes. Classical deformities in rheumatoid arthritis are the Boutonniere deformity (Hyperflexion at the proximal interphalangeal joint with hyperextension at the distal interphalangeal joint), swan neck deformity (Hyperextension at the proximal interphalangeal joint, hyperflexion at the distal interphalangeal joint). The thumb may develop a "Z-Thumb" deformity with fixed flexion and subluxation at the metacarpophalangeal joint, leading to a "squared" appearance in the hand.

Extra-articular manifestations also distinguish this disease from osteoarthritis (hence it is a multisystemic disease). For example, most patients also suffer of anemia, either as a consequence of the disease itself (anaemia of chronic disease) or as a consequence of gastrointestinal bleeding as a side effect of drugs used in treatment, especially NSAIDs (non-steroidal anti-inflammatory drugs) used for analgesia. Splenomegaly may occur with concurrent leukopaenia (Felty's syndrome), and lymphocytic infiltration may affect the salivary and lacrimal glands (Sjögren's syndrome)

Dermatological: Subcutaneous nodules on extensor surfaces, such as the elbows, are often present.

Pulmonary: The lungs may become involved as a part of the primary disease process or as a consequence of therapy. Fibrosis may occur spontaneously or as a consequence of therapy (for example methotrexate). Caplan's nodules are found as are pulmonary effusions.

Autoimmune: Vasculitic disorders, giving nail fold infarcts, neuropathies and nephropathies.

Renal: Amyloidosis, which can also give muscular pseudohypertrophy.

Cardiovascular: Pericarditis, valvulitis and fibrosis.

Ocular: Keratoconjunctivitis sicca (dry eyes), episcleritis and scleromalacia, which can lead to fissure and leaking of eye contents.

Neurological: There can be signs of mononeuritis multiplex and atlanto-axial subluxation. The latter is due to erosion of the odontoid process and or/transverse ligaments in the cervical spine's connection to the skull. Such an erosion (>3mm) can give rise to vertebrae slipping over one another and compressing the spinal cord. At first the patient experiences clumsiness but with undue care this can progress to quadraplegia.

Epidemiology
Rheumatoid arthritis occurs most frequently in the 20-40 age group, although can start at any age. It is strongly associated with the HLA marker DR4 (W4, W14 & W15 are associated with the disease and W10 & W13 are protective) - hence family history is an important risk factor. The disease is 3 times more common in women than men and up to 4 times more common in smokers than non-smokers.

Diagnosis

Diagnostic criteria
The American College of Rheumatology has defined (1987) the following criteria for the diagnosis of rheumatoid arthritis.

Morning stiffness of >1 hour.
Arthritis and soft-tissue swelling of >3 of 14 joints/joint groups
Arthritis of hand joints
Symmetric arthritis
Subcutaneous nodules in specific places
Rheumatoid factor at a level above the 95th percentile
Radiological changes suggestive of joint erosion
At least four criteria have to be met to establish the diagnosis, although many patients are treated despite not meeting the criteria.

Blood tests

When RA is being clinically suspected, immunological studies are required, such as rheumatoid factor [2] (RF, a specific antibody). A negative RF does not rule out RA; rather, the arthritis is called seronegative. During the first year of illness, rheumatoid factor is frequently negative. 80% patients eventually convert to seropositive status. RF is also seen in other illnesses, like Sjögren's syndrome, and in approximately 10% of the healthy population, therefore the test is not very specific.

Because of this low specificity, a new serological test has been developed in recent years, which tests for the presence of so called anti-citrullinated protein (ACP) antibodies. Like RF, this test can detect approximately 80% of all RA patients, but is rarely positive in non-RA patients, giving it a specificity of around 98%. In addition, ACP antibodies can be often detected in early stages of the disease, or even before disease onset. Currently, most common test for ACP antibodies is the anti-CCP[3] (cyclic citrulinated peptide) test.

Also, several other blood tests are usually done to allow for other causes of arthritis, such as lupus erythematosus. The erythrocyte sedimentation rate (ESR), C-reactive protein[4], full blood count, renal function, liver enzymes and immunological tests (e.g. antinuclear antibody/ANA)[5] are all performed at this stage. Ferritin can reveal hemochromatosis, which can mimic RA.

Pathophysiology

Joint abnormalities in rheumatoid arthritisThe cause of RA is still unknown to this day, but has long been suspected to be infectious. It could be due to food allergies or external organisms. Mycoplasma, Erysipelothrix, Epstein-Barr virus, parvovirus and rubella have been suspected but never supported in epidemiological studies. As in other autoimmune diseases, the "mistaken identity" theory suggests that an offending organism causes an immune response that leaves behind antibodies that are specific to that organism. The antibodies are not specific enough, though. They begin an immune attack against, in this case, the synovium, because some molecule in the synovium "looks like" a molecule on the offending organism that created the initial immune reaction - this phenomenon is called molecular mimicry.

Autoimmune diseases require that the affected individual have a defect in the ability to distinguish self from foreign molecules. This ability is acquired in the first year of life. There are markers on many cells that confer this self-identifying feature. However, some classes of markers allow for RA to happen. 90% of patients with RA have the cluster of markers known as the HLA-DR4/DR1 cluster, whereas only 40% of unaffected controls do. Thus, in theory, RA requires susceptibility to the disease through genetic endowment with specific markers and an infectious event that triggers an autoimmune response.

Once triggered, the immune response causes inflammation of the synovium. Early and intermediate molecular mediators of inflammation include tumor necrosis factor alpha (TNF-α), interleukins IL-1, IL-6, IL-8 and IL-15, transforming growth factor beta, fibroblast growth factor and platelet-derived growth factor. Modern pharmacological treatments of RA target these mediators. Once the inflammatory reaction is established, the synovium thickens, the cartilage and the underlying bone begins to disintegrate and evidence of joint destruction accrues.

Treatment

Pharmacological treatment of RA can be divided into disease-modifying antirheumatic drugs (DMARDs), anti-inflammatory agents and analgesics [1]. DMARDs have been found to produce durable remissions and delay or halt disease progression. This is not true of anti-inflammatories and analgesics.


Disease modifying anti-rheumatic drugs (DMARDs)
DMARDs can be further subdivided into xenobiotic agents and biological agents. Xenobiotic agents are those DMARDs that do not occur naturally in the body, as opposed to biologicals.


Xenobiotics
Xenobiotics include:

azathioprine
cyclosporin A
D-penicillamine
gold salts
hydroxychloroquine
leflunomide
methotrexate (MTX)
minocycline
sulfasalazine (SSZ)
The most important and most common adverse events relate to liver and bone marrow toxicity (MTX, SSZ, leflunomide, azathioprine, gold compounds, D-penicillamine), renal toxicity (cyclosporine A, parenteral gold salts, D-penicillamine), pneumonitis (MTX), allergic skin reactions (gold compounds, SSZ), autoimmunity (D-penicillamine, SSZ, minocycline) and infections (azathioprine, cyclosporine A). Hydroxychloroquine may cause ocular toxicity.


Biological agents
Biological agents include:

tumor necrosis factor (TNFα) blockers - etanercept (Enbrel), infliximab (Remicade), adalimumab (Humira)
interleukin-1 blockers - anakinra
Bristol-Myers Squibb Company announced on December 23, 2005, that the US Food and Drug Administration (FDA) has approved Orencia (abatacept), the first selective modulator of a costimulatory signal required for full T-cell activation, for the treatment of rheumatoid arthritis. Orencia is expected to be available for initial commercial use by the end of February 2006.


Anti-inflammatory agents and analgesics
Anti-inflammatory agents include:

glucocorticoids
Non-steroidal anti-inflammatory drug (NSAIDs, most also act as analgesics)
Analgesics include:

acetaminophen
opiates
lidocaine topical

Other therapies
Other therapies are weight loss, occupational therapy,physiotherapy, joint injections, and special tools to improve hard movements (e.g. special tin-openers).

Severely affected joints may require joint replacement surgery, such as knee replacement.


Epidemiology
The incidence of RA is 30 cases per 10,000 population. The peak incidence is between the ages of 20 and 40. The prevalence rate is 1%, with women affected three to five times as often as men. Some Native American groups have higher prevalence rates (5-6%) and black persons from the Caribbean region have lower prevalence rates. First-degree relatives prevalence rate is 2-3% and disease concordance in monozygotic twins is approximately 15-20%.


Prognosis
The course of the disease varies greatly from patient to patient. Some patients have mild short-term symptoms, but in most the disease is progressive for life. Around 20%-30% will have subcutaneous nodules (known as rheumatoid nodules) this is associated with a poor prognosis.


Disability
Daily living activities are impaired in most patients.
After 5 years of disease, approximately 33% of patients will not be working
After 10 years, approximately half will have substantial functional disability.

Prognostic factors
Poor prognostic factors include persistent synovitis, early erosive disease, extra-articular findings (including subcutaneous rheumatoid nodules), positive serum RF findings, positive serum anti-CCP autoantibodies, carriership of HLA-DR4 "Shared Epitope" alleles, family history of RA, poor functional status, socioeconomic factors, elevated acute phase response (erythrocyte sedimentation rate [ESR], C-reactive protein [CRP]), and increased clinical severity.

Mortality
Life expectancy for patients with RA is shortened by 5-10 years, although those who respond to therapy may have lower mortality rates.

Prevention
Regular exercise and carefully controlled diet can usually help lessen the pain and stiffness associated with arthritic flare-ups.

Cold can increase the pain and stiffness.

Also see Eastern and Naturopathic Approaches in this article.

History

The first known traces of arthritis date back as far as 4500 BC. It was noted in skeletal remains of Indians found in Tennessee. A text dated 123 AD first describes symptoms very similar to rheumatoid arthritis. In 1859 the disease got its current name.