Juvenile idiopathic arthritis (JIA), also known as juvenile arthritis and formerly known as juvenile rheumatoid arthritis (JRA),
JIA is an autoimmune, noninfective, inflammatory joint disease, the cause of which remains poorly understood. It is characterised by chronic joint inflammation. JIA is a subset of childhood arthritis, but unlike other, more transient forms of childhood arthritis, JIA is a lifelong condition with relapse of disease after treatment discontinuation being common. JIA has clinical and pathologic correlates to adult inflammatory and auto-immune arthritis, with the diseases believed to exist on a continuum from childhood to adulthood.
Signs and symptoms
Arthritis entails inflammation within the joint, and presents as swelling, pain, stiffness and restricted joint movement. Symptoms of JIA vary. This is because JIA has several subtypes, which differ according to the number of affected joints, severity of disease, age of onset, prognosis and presence or absence of inflammation in other parts of the body. Involvement of small joints of the hands and feet is more likely when many joints are affected ('polyarthritis'). Swollen joints may also feel warmer to touch. Swelling may be difficult to detect clinically, especially for joints such as those of the spine, sacroiliac joints, shoulder, hip, and jaw.
Joint pain is an important symptom, although some children experience minimal or no pain with their arthritis.
Swelling and pain usually result in limited movement of the affected joints, for example a knee held bent causing a limp, or being unable to make a full fist. Limited movement may reduce a child's ability to fully participate in activities and undertake usual tasks such as those used for self-care. In some JIA subtypes, more non-specific symptoms of being unwell may be present, such as lethargy, fatigue and poor appetite. Children with systemic JIA usually present with fever and a classic rash and may become quite ill. Late effects of arthritis can include joint contractures (stiff, bent joints with loss of movement) due to joint damage; limb length discrepancies and muscle wasting with muscle weakness.
Extra-articular
JIA is associated with inflammation in the front of the eye (acute or chronic anterior uveitis), which affects about one in six children with JIA. Eye involvement occurs most commonly in girls, those with only a few joints involved (oligoarthritis), those with rheumatoid factor negative polyarticular JIA, and those with a positive anti-nuclear antibody (ANA).
Children with JIA may have a reduced overall rate of growth, especially if the disease involves many joints or other body systems. This may be due to a combination of the disease itself, as well as its treatments, particularly corticosteroid use. Paradoxically, limbs where a large joint (such as the knee) is inflamed may have increased growth in the short term, leading to limb-length discrepancy (i.e. one arm or leg is slightly longer than the other). This is due to increased blood supply to the bony growth plates surrounding the inflamed joints. Bone density and bone strength may be reduced through a combination of inflammation, corticosteroid use and reduced physical activity levels.
Uveitis, if left untreated, can result in scarring, glaucoma, cataracts, and even blindness. Regular monitoring allows for early detection and treatment. Steroid eye drops are usually the first line treatment for anterior uveitis. However, other treatments – many of which also treat arthritis (e.g. methotrexate, biologics) – may be required to keep the inflammation under control, and to minimise steroid use over the longer term. Long term steroid use can contribute to the development of cataracts. — meaning that the body's own immune system starts to attack and destroy cells and tissues (particularly in the joints) for no apparent reason. The immune system is thought to be provoked by changes in the environment, in combination with mutations in many associated genes and/or other causes of differential expression of genes. Experimental studies have shown that certain mutated viruses may be able to trigger JIA. The disease appears to be more common in girls, and is most common in Caucasians.
The cause of JIA, as the word "idiopathic" suggests, is unknown and an area of active research. Current understanding of JIA suggests that it arises in a genetically susceptible individual due to environmental factors.
Diagnosis
The diagnosis of JIA can be difficult, in part because joint pain in children is so common and may be from many causes other than JIA. The characteristic feature of arthritis is joint swelling which is sometimes – but not always – associated with pain. The presence of joint stiffness is another typical feature, particularly when present in the morning and improving with activity.
No single test can confirm a diagnosis of JIA: a combination of presenting signs and symptoms, blood tests, and if necessary medical imaging, is used to make the diagnosis. The blood tests may measure levels of inflammatory markers, as well as the presence of specific immune markers which may include anti-nuclear antibody, HLA-B27, rheumatoid factor and anti–citrullinated protein antibody. These serological markers may be negative in children with JIA, and are often present in healthy children; as such they should not be interpreted in isolation but in the context of the clinical presentation. Many children with JIA have normal blood work. X-rays may be required to ensure that the joint pain and swelling is not from a fracture, cancer, infection, or congenital abnormality. In some cases, fluid from the joint can be aspirated and analysed to assist in making a diagnosis. This test can assist by ruling out other causes of arthritis such as infection.
Classification
The current classification system by the International League of Associations for Rheumatology (ILAR) recognizes seven distinct subtypes of JIA, based on their presentation within the first six months:
Each subtype has a specific pattern of features as outlined in the table and descriptions below. (The seventh category, not included in the table, is 'Undifferentiated' and includes any patient with JIA who does not meet criteria for other subtypes, or who meets criteria for two or more subtypes).
{| class="wikitable"
|-
! !! Oligoarticular !! Polyarticular (RF negative) !! Polyarticular (RF positive) !! Systemic Onset !! Psoriatic !! Enthesitis Related Arthritis
|-
| % of JIA || 50-60 || 20-30 || 5-10 || 10-20 || 5-15 || 15
|-
| Gender (F:M) || 4:1 || 4:1 || 9:1 || 1:1 || 3:2 || 1:9
|-
| Typical age of onset (years) || 2-12 (peak 2–3) || 2-12 (peak 2–3) || Adolescence || Any || Mid childhood || Adolescence
|-
| Joint Pattern || Asymmetric; often large joints (knee, ankle, wrist, elbow)
|| Often asymmetric; multiple small and large joints
|| Symmetric; multiple small and large joints
|| Symmetric; multiple small and large joints || Asymmetric; small and large joints including hips and especially DIPs || Asymmetric; large joints; axial
skeleton
|-
| Extra-articular Involvement || Uveitis in 20% || Painless uveitis (especially if ANA positive)
|| Rheumatoid Nodules || Fever, rash, lymphadenopathy, enlarged liver and spleen, Serositis
|| Psoriasis, nail pitting, dactylitis, uveitis in 10%, enthesitis
|| Symptomatic uveitis in 20%, enthesitis, IBD, aortitis
|}
Oligoarticular arthritis (Oligoarthritis)
Oligoarticular (or pauciarticular) JIA is the most common JIA subtype, and occurs when there are up to four joints involved during the first six months of disease. Two subtypes of oligoarticular arthritis exist: persistent oligoarthritis, where no more than four joints are affected throughout the whole disease course; and extended oligoarthritis, where more than four joints are affected after the first six months of disease. Patients in this subtype are often young, typically aged between 1 and 5 years, and are female preponderant.
Differential diagnosis
Several other disorders and diseases present themselves with symptoms like JIA. These causes include, but are not limited to, infectious (for example, septic arthritis or osteomyelitis) and post-infectious conditions (reactive arthritis, acute rheumatic fever, and in some geographic areas Lyme disease); hematologic and neoplastic diseases such as leukemia or bony tumors; and other connective tissue diseases (such as systemic lupus erythematosus). For the systemic-onset form of JIA, the differential diagnosis also includes Kawasaki disease and periodic fever syndromes. Some genetic skeletal dysplasias, such as forms of mucopolysaccharidosis, especially type 1 Scheie syndrome, progressive pseudo-rheumatoid dysplasia, and multicentric osteolysis, nodulosis, and arthropathy syndrome Rarely, metabolic diseases, such as Farber disease, may also mimic JIA. Patients with Farber disease typically have subcutaneous nodules and a hoarse or weak voice due to laryngeal nodules.
Treatment
The major emphasis of the treatment of JIA is helping the child or young person regain normal levels of physical and social functioning by controlling inflammation and extra-articular symptoms. Clinical remission should be the primary target for all people. Prompt recognition and management is important as early initiation of medication therapy increases the likelihood of a response to first-line treatments and low disability. Consensus treatment guidelines exist for the treatment of JIA.
Optimal management of JIA requires a multidisciplinary team working to address the needs of an individual child. Optimizing physical and social functioning is accomplished using non-pharmacological strategies such as physical therapies, pain management strategies, and social supports. Medications are used to control inflammation and reduce or prevent extra-articular symptoms.
Surgery is only used to treat the most severe cases of JIA and is now rarely required.
There is variation in the exact exercise prescription which best promotes musculoskeletal health whilst reducing fatigue, pain and swelling. Consensus is that children with JIA should be following national public health standards of physical activity and participating in moderate fitness, flexibility, and strengthening exercises, compatible with their abilities and disease restrictions. Current physical activity guidelines for children recommend at least 60 minutes of moderate to vigorous activity daily, including vigorous activity on at least three days per week. Although research highlights the benefits of various forms of physical activity for improving health outcomes in children JIA, many parents and children remain hesitant that exercise may worsen symptoms. This fear, combined with the lack of clear exercise guidance in clinical settings, creates uncertainty and hesitation about appropriate PA recommendations. Encouraging healthy habits early in life and addressing fear-avoidance behaviors in children with JIA can enhance both musculoskeletal and cardiovascular health.
A Cochrane meta-analysis looking at existing RCTs showed in all studies that exercise does not have a detrimental effect on JIA. In fact, there is evidence to show that both low and high-intensity exercise programs result in improved physical function and reduced pain in children with JIA. Guidelines indicate that children with JIA should be encouraged to be physically active and can safely participate in sports without disease exacerbation. Those with actively inflamed joints should limit activities within pain limits, then gradually return to full activity following a disease flare. Studies found that a 12-week exercise program of weight-bearing exercise plus standardized muscle strengthening exercises for children with JIA led to significant improvements in bone mineral density, bringing measurements for children with JIA within the reference range of healthy children.
Self-management
Pain is the most common and often the most distressing symptom of JIA (although some children with JIA do have joint inflammation without any pain at all). Pain can occur even when children are receiving effective doses of therapies which are managing their underlying disease. A multinational study showed that pain is a predictor of psycho-social well-being. Several studies has also shown that pain at debut is a strong predictor of persistent pain.
Pain has been found to negatively impact all aspects of quality of life and is associated with a reduction in physical, social and emotional functioning. Children who have higher levels of pain tend to have reduced levels of socialization, school attendance and participation in activities. Increased pain is also correlated with poor sleep and higher fatigue in children with JIA.
Education and employment
Educational and vocational accommodations in those with JIA may include requiring extra time to get between classes or during examinations, using specialized pens or switching to typing rather than handwriting, or minimizing the load of heavy books or equipment to be carried in a child's school bag. The exact requirements will vary from child-to-child and will depend on the joints affected. In many instances, the child's treating team will be able to provide specific advice and information for teachers and coaches to smooth the transition back to school.
eHealth and mobile Health (mHealth) interventions
A new emerging area of support for disease management is through digital technology using eHealth and mobile health (mHealth) interventions. These interventions have to potential to support the development of self-management skills, or assist the healthcare team to monitor symptoms. For JIA, current studies have focused on the health issues pain, health related quality of life, physical activity and disease management. Children and adolescents have used these interventions through a range of devices including computers, laptops, personal digital assistants, multimedia-players, and wearable accelerometers synchronised to smart phone. This allows access to these interventions from home. Early usability studies have been gaining positive feedback by children and adolescents. They are familiar with this type of technology and report liking these interventions. However further research is still needed to understand their full potential in supporting children and adolescents living with complex needs.
Prognosis
The use of DMARDs in the management of JIA have made disease-free remission achievable for the majority of children with JIA. Research is currently being undertaken into clinical prediction models to allow earlier identification of children who are likely to have a worse prognosis. Compliance with therapy, especially medications, has a positive correlation with disease outcome. Disease recurrence after medical therapy discontinuation is high, with 30-100% of children having clinical relapse of disease after treatment discontinuation.
Epidemiology
Juvenile Idiopathic Arthritis is the most common chronic rheumatic disease of childhood. In high-income countries, yearly incidence has been estimated at 2–20 cases per 100,000 population; prevalence in these areas is estimated at 16–150 cases per 100,000 population. However, there is also a suggestion that these numbers underestimate disease prevalence: one community-based survey of school children in Western Australia reported a prevalence of 400 per 100,000. Overall prevalence is often reported as one per thousand children.
Incidence and prevalence data vary across different population and ethnic groups, with lower overall prevalence in Afro-Caribbean and Asian populations. There are also ethnic differences in the frequency of JIA subtypes: for example, oligoarthritis is the most common subtype in European populations, whilst polyarticular disease predominates in many other countries including Costa Rica, India, New Zealand, and South Africa.
Terminology
The terminology used to describe JIA is evolving, and each term has some limitations.
Previous terminology included Juvenile Rheumatoid Arthritis and Juvenile Chronic Arthritis. These terms were replaced in 1997 with the release of the revised ILAR (International League of Associations for Rheumatology) classification criteria.
There is currently an international movement underway to further revise the classification criteria for JIA, although this is in a preliminary phase.
MeSH uses "juvenile arthritis" as the primary entry, and uses "idiopathic", "chronic" and "rheumatoid" in alternate entries.
Society
Some famous people with this condition are:
- Antoni Gaudi, architect
- Clark Middleton, actor
- Claire Cottrill, singer-songwriter
- Rosemary Sutcliff, author
References
External links
- Arthritis Australia, Juvenile Idiopathic Arthritis
- JIA@NRAS (UK)
- JIA - NIH Medline Plus.