Still's disease is a systemic autoinflammatory disease with a childhood form, known as systemic juvenile idiopathic arthritis (SJIA), and a similar adult form, called adult-onset Still’s disease (AOSD).
SJIA is a rare type of arthritis that causes inflammation in young people Many parts of the body can be affected by SJIA, which is why it’s called systemic. Likewise, juvenile in the name means that it begins in childhood and idiopathic means that the cause is unknown.1
Symptoms of SJIA usually first occur in children aged two years or younger, and up to 30% still experience symptoms 10 years after their first symptoms. There is no cure for SJIA but remission (a decrease in disease severity) is possible over time and with treatment.1, 2, 3, 4
SJIA symptoms come and go in flares – periods lasting at least two weeks with reoccurring bouts of fever, with high daily temperature spikes, a skin rash, and painful, stiff joints.5, 6, 7
SJIA belongs to a group of autoinflammatory diseases called juvenile idiopathic arthritis (JIA) – SJIA affects around 10-20% of people with JIA.1 Autoinflammatory diseases are characterized by an overactive immune system – the body’s defense system against invaders like bacteria and viruses. In SJIA, the immune system is triggered even when there is no invasion to fight, resulting in damage to the body.
The symptoms of SJIA can be classified in two stages: symptoms associated with short-term flares and those caused by long-term build-up of damage to various parts of the body.
The first and most common symptoms of SJIA are recurrent bouts of fever with high daily temperature spikes, rashes, and painful joints. A flare of SJIA symptoms often causes:1,5,6,7
Children with SJIA are more likely to develop heart and lung problems, and any breathing or heart-related concerns should be raised with a doctor as soon as possible.1,5 SJIA can also interfere with normal bone growth and can lead to a limb being longer than the other or overall stunted growth.1
Possible symptoms of SJIA 5,6,7
SJIA has also been associated with serious health complications including macrophage activation syndrome (MAS) and amyloidosis. MAS is a serious complication of rheumatic diseases (conditions that affect the joints) caused by activation and uncontrolled multiplication of an immune cell called macrophages. It occurs in about 5-8% of children with SJIA and it can lead to life-threatening systemic symptoms and internal organ failure.5,6,8 Amyloidosis is a condition in which there is an abnormal build-up of a protein called amyloid in the kidneys that can lead to kidney failure. Improved diagnostics and treatment options mean that kidney damage caused by amyloidosis occurs less frequently than in the past.5, 9
If the condition is poorly controlled, SJIA can cause painful and lasting damage to various parts of the body that can seriously affect quality of life. The earlier SJIA is recognized and treated, the better the outcome is likely to be.
As the ‘idiopathic’ in the name suggests, the cause of SJIA is unknown, but it has been suggested that certain children have a genetic disposition, which is then triggered by something in their environment such as an infection.1 New theories suggest there may be several factors working together that cause SJIA to develop. 10
SJIA occurs worldwide and affects boys and girls equally.6 In Europe it is estimated that each year less than one child per 100,000 develops SJIA.10 The number of all people who currently have SJIA is estimated to be between 5 and 15 people in every 100,000. 11, 12, 13
With SJIA, people with the condition typically experience flares of symptoms, with some having healthy periods between these flares. The course and severity of SJIA can be vastly different from person to person.3, 14, 15 As shown in the diagrams below, a person can experience a monocyclic disease course, in which they recover completely after a number of years. Others can experience recurrent episodes of disease with by periods of remission in-between. Finally, some people experience persistent symptoms.
Possible disease courses of SJIA 3, 14, 15
In most cases, children with symptoms associated with SJIA are referred to doctors called rheumatologists who specialize in skeletal and autoinflammatory diseases. Pediatric rheumatologists will be best placed to help diagnose SJIA based on their knowledge and experience.
A diagnosis of SJIA is made based on a child’s medical symptoms such as a high fever for at least two weeks, joint pain and inflammation for at least six weeks, and a comprehensive physical exam. There are no specific tests for SJIA, but imaging tests like X-rays or ultrasound are often used to detect joint, lung or heart inflammation and the doctor may take a small amount of blood for various laboratory tests that help support or rule out an SJIA diagnosis.1
Currently, there is no cure for SJIA, but there have been advances for treatments in recent years, making remission possible.1
The first treatment options for SJIA tend to be so called non-steroidal anti-inflammatory drugs (NSAIDs) that can reduce the pain, inflammation and stiffness. If necessary, more powerful corticosteroids (drugs that lower inflammation) or biologics (drugs that target and block inflammation causing substances in the body) may be prescribed.1Exercise is also an important part of any SJIA therapy, as it will help build muscle strength, increase energy and reduce pain.
It’s important to prepare for each medical appointment, as good communication with doctors and specialists ensures that you understand what your child’s diagnosis means and what treatment options are available.
Read more on how to prepare for a doctor’s appointment here.
For any child, having SJIA represents a huge burden with daily limitations. In addition to the physical impact, it can upset their emotional wellbeing and overall development.
It’s important that families offer extra support and that teachers are informed to help your child in day-to-day activities and their overall development. Find more information and advice on the day-to-day management of SJIA here or follow the inspiring stories of other children and their families here.
Find more information and support on SJIA and autoinflammatory diseases here.