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Introduction
Juvenile rheumatoid arthritis (JRA) is a condition of chronic synovitis in children of which there are several distinct subgroups (Table 1). The classic adult-type rheumatoid arthritis does occur in children but is quite rare, the JRA subgroups seronegative* polyarthritis and systemic-onset disease also occur in adults but not frequently, the pauciarthritis of early childhood has not been recognized in adults, and
Incidence and Epidemiology
The true incidence of JRA is not known. Based on the estimate that approximately 5% of all cases of chronic so-called "rheumatoid" arthritis begin during childhood, there would be about 250,000 children who have JRA in the
No causes or risk factors have been identified for JRA. Antecedent causes that frequently are mentioned include infectious agents, immunologic abnormalities of the host, physical trauma to joints, psychological trauma to the child, and allergy or
Pathophysiology
The synovial tissue, or lining tissue of the joint, is the target for inflammation in JRA. Early results of synovial inflammation include hypertrophy of
TABLE 1. Recognizable Subgroups Of JRA
% OF
SUBGROUP PATIENTS CHARACTERISTICS
Systemic-onset Disease 10% to 20% Systemic manifestations
Slight male preponderance
Seronegativity: RF* and
ANA*
Severe arthritis in 25%
Polyarticular Disease 20% to 30% Symmetric polyarthritis of
RF-negative polyarthritis small and large joints
Female preponderance
Early or late childhood
onset
ANA in 25%
Rheumatoid nodules
common
Severe arthritis in 10%
to 15%
RF-positive polyarthritis 5% to 10% Symmetric polyarthritis of small and large joints
Female preponderance
Late childhood onset
ANA in 50% to 75%
Rheumatoid nodules
common
Severe arthritis in >50%
Pauciarticular Disease 30% to 40% Arthritis of few joints
Early childhood-onset Hips/sacroiliac joints spared
Female preponderance
Early childhood onset
ANA in 60%, RF-negative
Chronic iridocyclitis in 30%
Mild arthritis
Late childhood-onset 10% to 15% Arthritis of few joints Hips/sacroiliacs often
affected
Male preponderance
Late childhood onset
ANA-negative, RF-negative
HLA-B27 in 75%
Some will have spondyloarthropathy as adults
*RF = rheumatoid factor; ANA = antinuclear antibodies.
The etiologic agent or agents for the synovitis in JRA are unknown. The synovitis is characterized by its chronicity. Immunologic mechanisms such as immune complex disease may perpetuate the synovitis, but full explanations for the chronicity of synovial inflammation remain to be found. If synovitis persists long enough in an individual joint, structures of the joint may be damaged. Because articular cartilage does not regenerate well, this destruction may be permanent. Fortunately, many children who
TABLE 2. Names Currently Used To Describe Condition(s) of Chronic Synovitis in Children
$ Juvenile rheumatoid arthritis
$ Juvenile chronic polyarthritis
$ Juvenile chronic arthritis
$ Still disease
$ Chronic childhood arthritis
JRA may involve other organ systems in addition to the joints, and patterns of organ involvement differ in various subgroups. Possible extraarticular manifestations include the iridocyclitis of early childhood pauciarticular disease; the rheumatoid nodules and rheumatoid vasculitis of seropositive disease; the fevers, rash, polyserositis, hepatosplenomegaly, lymphadenopathy, anemia, leukocytosis, and (rarely)
Clinical Manifestations
The clinical manifestations of JRA are diverse. Although a number of clinically distinct subgroups of disease have been suggested, there is no complete agreement as to which subgroups are valid. The American Rheumatism Association currently recognizes three subgroups: systemic-onset disease, polyarticular-onset disease, and
TABLE 3. Objective Signs of Arthritis
Joint Swelling
--Synovial hypertrophy
--Increased amounts of synovial fluid
--Swelling of periarticular tissues
Joint Pain
--On motion
--On palpation (tenderness)
--At rest
Loss of Joint Motion
--Stiffness of joints
Joint Warmth
Joint Erythema
Clinical Features
SYSTEMIC-ONSET JRA Systemic-onset JRA, characterized by high intermittent fevers and other extraarticular manifestations (Table 4), affects about 10% to 20% of all patients who have JRA. There is a slight male preponderance. The disease may present at any age during childhood and occasionally presents during adulthood.
The characteristic fevers of systemic-onset JRA are high and intermittent, with elevations to 39.5EC (103EF) or higher once or twice daily and subsequent returns to normal or
*Necessary for diagnosis
Prominent musculoskeletal involvement usually is manifest early in disease, although this may be overlooked in the face of the systemic illness. Nearly all children have severe myalgia, arthralgia, or transient arthritis during periods of temperature elevation; such transient musculoskeletal complaints may
POLYARTICULAR JRA
Polyarticular disease without the prominent systemic manifestations of systemic-onset JRA affects about 35% of children who have chronic arthritis. Two subgroups
Seronegative JRA
This subgroup of disease is heralded by the insidious or sudden onset of polyarthritis, often in early childhood. The high fevers and rash of systemic-onset
Seropositive JRA
This type of disease also is heralded by the sudden or insidious onset of arthritis, usually in many joints. Patients typically are older than 8 years at onset. Subcutaneous rheumatoid nodules often are found over pressure points, notably the elbows, the heels, the first metatarsophalangeal joints, and the knuckles and
PAUCIARTICULAR ARTHRITIS
Pauciarticular arthritis, or arthritis limited to only a few joints (Latin: pauci-few, articulus-joint), affects 40% to 50% of children who have JRA. This subgroup designation implies that arthritis remains limited to a few joints for the first
Early Childhood-onset
This subgroup, associated with chronic iridocyclitis and ANAs, appears to include 30% to 40% of all patients who have JRA. Girls are affected predominantly, and the
Later Childhood-onset
Pauciarticular disease associated with sacroiliitis and HLA B27 affects 10% to 15% of children who have so-called JRA. Males are affected predominantly, and the
Diagnosis
Diagnosis of JRA rests on several bases (Table 5): onset of disease during
Laboratory Studies
There are no specific or diagnostic laboratory tests for JRA. Acute phase reactants such as the erythrocyte sedimentation rate and C-reactive protein generally are elevated and present during periods of inflammation, but none of these tests is
Therapy
A number of considerations are important in designing therapy for children who have JRA. These include identification of the particular disease manifestations
ANTI-INFLAMMATORY AND ANTIRHEUMATIC AGENTS
When planning therapy for the arthritic and musculoskeletal manifestations of JRA, the physician initially should determine the extent of joint involvement, the activity of the synovitis, the amount of joint destruction, the status of muscle strength,
Nonsteroidal anti-inflammatory drugs (NSAIDs) remain front-line and important agents in the treatment of JRA. NSAIDs available for use in children in the United States include salicylates, naproxen, tolmetin, ibuprofen, and indomethacin; a number of other agents are used in adult medicine but are not yet approved for use in
Methotrexate has been shown to be an effective agent in many children who have severe JRA, and it is moving to the fore in the therapy of children whose disease is
"Disease-modifying" therapies that are being tried in therapy of JRA include sulfasalazine, intravenous immunoglobulin, corticosteroid therapy in various forms, and cyclosporin. Sulfasalazine is being used rather widely. Although
SURGERY
Orthopedic surgery can play a role in therapy of JRA. Synovectomy, the removal of inflamed synovial tissue, is of very limited usefulness in early therapy, but orthopedic surgery has great promise in the rehabilitation of children who have severe JRA. Leg length inequality, which may result from asymmetric arthritis affecting the knees
THERAPY OF SYSTEMIC MANIFESTATIONS
The systemic manifestations of systemic-onset JRA often respond to nonsteroidal therapy. Prolonged debilitating fevers and malaise, pericarditis or myocarditis with threat of cardiac decompensation, or severe anemia may be causes for