The symptoms of Adult-onset Still's disease may include joint and muscle pain in the knees, ankles, and wrists.
Still's disease flare-ups happen abruptly, usually beginning with a high fever and a rash. In some cases this may occur only once and resolve. In other cases, these symptoms may come back as flare-ups. In a third group, the symptoms may transition into more chronic joint aches and pain.
After the first episode, some people experience a long-lasting remission. However, for others, joint inflammation lingers and spreads throughout the body. Over time, this inflammation can develop into chronic arthritis.
Cause and symptoms
Although the exact cause of adult-onset Still's disease remains unknown, one theory is that it is triggered by an infection.
While a healthy immune system can fight off microbes in a healthy way, some people with certain genetic mutations may be more prone to damaging inflammation.
Researchers have not yet been able to identify a microbe or group of microbes that cause the disease. A further complication is that the disease does not appear to be due to a single genetic mutation. Instead, there seem to be many genes involved, varying from person to person.
The symptoms of the disease vary widely, too. According to the National Organization for Rare Disorders, some of the more common symptoms include:
- A spiking fever greater than 102.2° F. During an episode of adult-onset Still's disease, fevers occur daily and peak in the late afternoon or early evening.
- A rash, usually accompanying a fever, mostly affecting the chest and thighs. It is pink in color and tends to fade quickly.
- Joint and muscle pain is common. The knees, wrists, and ankles are most often affected, becoming swollen, stiff, or inflamed. This pain can be very intense and worsens during fevers.
Though less common, some other symptoms include:
- A sore throat before or during the first month of the disease.
- Spleen, liver, or lymph node enlargement.
- Chest pain or breathing difficulty, which can be caused by inflammation of the membrane around the heart, inflammation of the heart muscle itself, or inflammation of the membrane lining the chest cavity.
As the cause of adult-onset Still's disease remains unknown, there are no tests available to distinguish it from similar conditions. Instead, doctors diagnose the condition by gathering as much information as possible about what a person is experiencing, and then eliminating other diseases one by one.
Some important diagnostic steps include:
- Thoroughly evaluating a person's symptoms and medical history.
- Performing X-rays to detect changes in bones and joints, as well as swelling of the liver or spleen.
- Checking blood for abnormalities linked to adult-onset Still's disease, including raised white blood cell levels, low red blood cell levels, deficiency of the iron-carrying protein ferritin, and results that signal inflammation in the body.
- Running lab tests to rule out other autoinflammatory or autoimmune diseases, as well as certain cancers.
There are three types of adult-onset Still's disease:
- Monophasic: symptoms that happen once.
- Polycyclic or intermittent: There is more than one flare-up.
- Chronic: The disease progresses, and symptoms almost always involve joints.
The symptoms of Adult-onset Still's disease may be treated with NSAIDs, such as ibuprofen.
While there is no cure for adult-onset Still's disease, treatment can ease symptoms, slow progression, and help a person stay in remission.
A doctor will choose an appropriate treatment approach depending on the disease type, its severity, and the primary symptoms.
Below are the therapies currently available, which may be taken alone or in combination with others:
Nonsteroidal anti-inflammatory drugs (NSAIDs)
These drugs, such as ibuprofen or naproxen, can be used to treat the early symptoms of a flare-up, including fever and intense joint pain. However, people should only use them temporarily, as their long-term risks are greater than their benefits.
According to a 2014 review in the journal Therapeutics and Clinical Risk Management, some 80 percent of people with adult-onset Still's disease did not achieve remission with NSAIDs alone. Also, 20 percent of those taking NSAIDs had side effects, including gastrointestinal problems.
Doctors usually prescribe corticosteroids as the first approach to achieving remission in a person with adult-onset Still's disease.
The drugs can ease inflammation and pain over time and are often administered at a high initial dosage, which is then slowly reduced.
However, long-term usage of corticosteroids also poses some serious risks. One of the most concerning of these is steroid dependency, which occurred in 45 percent of the people considered in the 2014 review quoted above.
For more severe cases, doctors often try to combine corticosteroids with other drugs. Doctors refer to these drugs as "steroid-sparing agents," as they allow them to prescribe lower dosages of corticosteroid.
Methotrexate is usually the steroid-sparing agent of choice for severe cases of adult-onset Still's disease, because it suppresses the immune system's over-reaction. The drug is also used to treat arthritis and other rheumatic disorders.
Targeted biologic therapies
These are the newest form of treatment available. They are used only if a person's symptoms are unresponsive to more traditional therapies. Targeted biologic drugs aim to get to the root of the problem, blocking the specific immune cells and proteins that are responsible for the abnormal inflammatory response.
A promising example is anakinra, a drug that blocks the activity of an immune system protein called interleukin-1. Interleukin-1 signals the inflammatory response to jump into action, and researchers believe that elevated levels may play a role in adult-onset Still's disease.
Anakinra is still being tested, but it has been effective in rapidly relieving flare-ups in the small number of people with adult-onset Still's disease who have used it.
Because symptoms, progression, and responsiveness to therapy are highly variable, prognoses for this condition also differ from person to person.
For some people, adult-onset Still's disease may have little effect on their lives, while others may experience significant joint damage, which may cause real problems for their mobility.
The best way to protect the joints from damage is to try to keep inflammation under control. For people with chronic adult-onset Still's disease, this means finding a long-term treatment that works well for them. For people in remission, it might mean taking a low dose of corticosteroid, as maintenance.
People who experience side effects should consult a doctor. Using corticosteroids long-term can lead to bone thinning, so it may be necessary to take calcium and vitamin D supplements. Maintaining a healthy diet and lifestyle will also help to keep bones, muscles, and joints as healthy as possible.
Early detection of the disease is the best way to get early treatment. Unfortunately, because of the wide range of symptoms and the rarity of the disorder, adult-onset Still's disease often goes undiagnosed.
Hopefully, further research into the causes of Still's disease will allow scientists to develop more accurate diagnostic tests, assuring better treatments and outlooks.