Early intervention is key in juvenile idiopathic arthritis
How should children be examined?
What investigations should be carried out?
What are the evidence-based treatment options?
Juvenile idiopathic arthritis (JIA) is one of the most common chronic diseases of childhood. JIA is defined as arthritis of unknown cause, beginning before the age of 16, that persists for at least six weeks. The annual incidence in the UK is 1 in 10,000 children and the prevalence is 1 in 1,000. JIA occurs in all races and geographical areas and is more common in girls.1 The age of onset peaks between three and six and then again around adolescence.
As most children with JIA will first present to primary care, GPs have an important role in diagnosis and management. It is important that a thorough assessment is carried out, if the diagnosis is suspected on clinical grounds, to allow referral as early as possible to a paediatric rheumatologist and ophthalmologist. After confirmation of the diagnosis, the GP will be involved in monitoring the condition using blood tests to assess disease activity and side-effects of treatment. This can be very helpful in bringing poor disease control to the attention of secondary care physicians. JIA has emotional and psychosocial implications for both the child and the family and GPs may be involved in supporting the family through this often difficult time.
Each subtype of JIA varies in presentation. Arthritis may present as swelling or reduced range of movement of a joint accompanied by features of inflammation such as warmth, pain or tenderness. Often pain is not a significant feature and children may simply present with a swollen joint.
Oligoarticular JIA is the most common form of the disease accounting for around 50% of all cases. It affects one to four joints (mainly large joints, especially knees) during the first six months of the disease but may progress to involve more joints over time.3 RF positivity is an exclusion criteria for the diagnosis of oligoarticular JIA.
Polyarticular JIA affects five or more joints within the first six months of the disease.2 The mean age of onset is six and a half with peaks in the pre-school and pre-adolescent years. Patients may be positive or negative for RF. For a diagnosis of polyarticular JIA with positive RF to be made, a positive result for RF needs to be obtained on two occasions at least three months apart.3
Systemic onset JIA
Previously known as Still's disease, systemic onset JIA causes arthritis accompanied, or preceded, by fever in a quotidian pattern for at least three days. The fever spikes to over 39°C once or twice a day and returns to below 37°C in between. Other features include an evanescent, salmon pink erythematous rash that tends to occur with the spikes of fever and may only be apparent in the axillae, generalised lymphadenopathy, hepatomegaly and/or splenomegaly and serositis such as pericarditis, pleuritis or peritonitis.
Enthesitis related arthritis
Enthesitis related arthritis (ERA) usually manifests as a combination of arthritis and enthesitis (inflammation of tendon insertions, ligaments or joint capsule).
Juvenile psoriatic arthritis
Juvenile psoriatic arthritis is a combination of arthritis and psoriasis.
Arthritis that does not meet the inclusion criteria for any of the above categories, or fulfils criteria for more than one category is termed undifferentiated arthritis.3
The diagnosis of JIA is made clinically in combination with the judicious use of investigations. When a child presents in primary care with a painful/swollen joint that has not been caused by trauma, the GP should obtain a thorough history from the child and/or the parents/carer. It is important to examine ‘every joint, every time' as it is often difficult for children to localise pain and stiffness. This also helps avoid unnecessary joint aspiration for suspected sepsis when an oligo/polyarthritis is evident.
At the initial visit, a full examination should be performed to look for any rash, nail changes, mouth ulcers, hepatosplenomegaly and respiratory or cardiac abnormalities. The differential diagnosis of JIA encompasses a wide range of conditions which should be considered during assessment. A paediatric gait, arms, legs and spine (pGALS) examination is a useful screening tool4 that can be used in general practice.
As no diagnostic test exists for JIA, investigations are used to support the diagnosis. Inflammatory markers and FBC can be helpful in supporting the diagnosis when deciding to refer. After discussion with a paediatric rheumatologist it may be appropriate to obtain further investigations which form a routine part of the secondary care assessment. This includes x-rays, autoimmune profile (C3, C4, dsDNA, immunoglobulins) and parameters for classifying the disease (RF, ANA, HLA B27). In early disease, joint x-rays are usually normal but may show a joint effusion, peri-articular osteoporosis or soft tissue swelling. Occasionally alternative diagnoses such as fracture, osteomyelitis or malignancy are seen on plain x-rays. Ultrasound is increasingly used and may show joint effusions and synovitis. MRI demonstrates joint anatomy in excellent detail, see figure 1 above, and can reveal early pre-erosive changes in the articular cartilage.
In monoarthritis, arthrocentesis is required to exclude septic arthritis, even in established JIA, as these joints are at greater risk of infection. In JIA, aspiration of straw-coloured fluid with a high white cell count but no organism on culture is a typical finding. Children, especially younger ones, require sedation before joint aspiration and injection.
All children with possible JIA should be referred urgently to a paediatric rheumatologist as soon as possible in order to confirm the diagnosis and consider early institution of DMARD therapy. Once the diagnosis is confirmed, any child with JIA should be considered at risk of uveitis and subsequent blindness and therefore immediate referral to a paediatric ophthalmologist is mandatory.
In areas where specialised paediatric rheumatologists or ophthalmologists are not available there are often consultants with an interest in managing the paediatric cases of their specialty. The child should be referred to such specialists first before accessing tertiary referral centres.
Complications can arise as a result of the disease itself or as a consequence of its treatment. Anterior uveitis occurs in 8-30% of JIA patients overall, increasing to 45-57% in young female patients with oligoarticular disease who are antinuclear antibody positive.5
NSAIDS and steroids
Once the diagnosis is suspected, symptomatic treatment with simple analgesics and NSAIDs can be initiated while waiting for a specialist opinion.
NSAIDs are helpful in providing symptomatic relief but have no disease-modifying effect.
Glucocorticoids are well established in the treatment of JIA and may be given either intra-articularly, orally or in severe disease, intravenously. The maxim of the smallest dose given for the shortest time must be adhered to.
Methotrexate is the first-line disease-modifying anti-rheumatic drug (DMARD) used in JIA. It is safe, reliable and effective in 60-70% of cases and may be given orally or subcutaneously. Appropriate counselling and confirmation of varicella immunity are essential before starting treatment with methotrexate.
Children on methotrexate must avoid all live vaccinations and seek advice from the paediatric rheumatology team in the case of acute infection as doses may need to be withheld. Regular monitoring with FBC and LFTs is required to check for toxicity. Other DMARDs which can be used include sulphasalazine especially for ERA and hydroxycholoroquine in conjunction with methotrexate.3
Biological therapy has revolutionised the treatment of inflammatory arthritis. Children who have poorly controlled disease on methotrexate or who are unable to tolerate the drug may be given anti-TNF? treatment. Etanercept and adalimumab are licensed for treatment of JIA. NICE has issued guidance on the use of anti-TNF? in JIA.9 Studies with these agents have shown high response rates10,11 which are improved by using combination therapy with methotrexate.12 Anakinra is a recombinant IL-1 receptor antagonist that may also be useful in systemic onset JIA.13 A newer biological agent, tocilizumab, (an IL-6 inhibitor) is showing great promise for the treatment of JIA.14
Autologous stem cell transplantation is only used in exceptionally severe cases of JIA. Orthopaedic or maxillofacial surgery may be required for joint deformities, contractures and micrognathia. As in adults, joint replacement may be necessary.
Long-term follow up of children with JIA shows that the arthritis persists into adulthood in up to 40% of cases with 30-50% of these patients having severely compromised function.15 Unemployment rates are three times higher than the general population, regardless of educational capability. The prognosis of JIA is being improved, however, by intensive intervention early in the disease.
Although JIA is a rare condition, failure to recognise the disorder may have severe long-term consequences for the patient. All children with JIA must be screened for anterior uveitis as failure to detect this may lead to blindness. The shift towards early intensive treatment aims to control disease rapidly to maximise outcome.Knee joint MRI of a child with JIA (psoriatic arthritis) showing a very large effusion extending into the supra-patellar region and considerable synovial thickening Figure 1 Authors
Dr Maliha F Shaikh
Clinical research fellow, Rheumatology Clinical Research Unit, Addenbrooke's Hospital, Cambridge
Andrew J K Östör MB BS FRACP
Consultant rheumatologist and associate lecturer,
School of Clinical Medicine,
University of Cambridge
Director, Rheumatology Clinical Research Unit