Adult-Onset Still's Disease (AOSD)

What is adult-onset Still’s disease (AOSD)?

Adult-onset Still’s disease (AOSD) is a rare type of inflammatory arthritis that affects your whole body. It causes joint and muscle pain, a daily fever and a rash. It can also cause other systemic (whole-body) symptoms.

AOSD is an adult form of juvenile Still’s disease (juvenile idiopathic arthritis, JIA). It typically occurs in younger adults, between the ages of 16 and 35. Like JIA, the condition may be temporary, lasting less than a year, or may come and go for a long time. Symptom “flares” may occur regularly or far apart, and they may be mild to severe. Medications can help manage your symptoms when they arise.

Types of adult-onset Still’s disease

Adult-onset Still’s disease affects different people in different ways, and it’s hard to predict how it will affect you. But healthcare providers have observed that symptoms usually occur in one of three ways:

• Monophasic AOSD. Monophasic means there’s only one episode of symptoms, lasting weeks or months, but less than a year. This form may occur suddenly and go away just as suddenly.
• Polyphasic AOSD. Polyphasic means there are multiple episodes of symptoms. They occur periodically, weeks, months or years apart. They usually get shorter and less severe over time.
• Chronic AOSD. Chronic means that you have persistent symptoms or regular flares. Chronic AOSD is more likely to do progressive damage to your joints, as rheumatoid arthritis does.

Each of these types occurs with about equal frequency. But you can’t always tell which type it is right away. Sometimes, what seems to be monophasic or polyphasic AOSD later develops into chronic AOSD.

What are the symptoms of adult-onset Still’s disease?

The primary symptoms include:

• Fever. When symptoms are active, most people have a daily fever with two spikes, one in the morning and one in the evening. Fever spikes are typically over 102 degrees Fahrenheit (39 degrees Celsius).
• Skin rash. A pink or salmon-colored rash usually appears when your fever is spiking. It may disappear in between spikes. It usually affects your chest, arms and legs first, but may spread.
• Joint pain. Most people feel achy in their joints, and many also experience swelling and stiffness. It may start in a few joints at first, but after a while, you may start to feel it all over.
• Muscle pain. You may also feel achy in your muscles, especially when your fever is spiking.

Other common symptoms include:

• Sore throat.
• Abdominal pain.
• Fatigue.
• Malaise.

What does adult-onset Still’s disease feel like?

At first, adult-onset Still’s disease might feel a lot like a virus or the flu. Symptoms like a fever, body aches and a sore throat resemble many common illnesses. You and your healthcare provider might become more suspicious when your symptoms still haven’t gone away after two or three weeks.

What causes adult-onset Still’s disease?

Inflammation in your body causes the symptoms of adult-onset Still’s disease. Your immune system usually generates inflammation to fight infections and heal injuries. It’s supposed to be a temporary intervention. But in certain diseases, like AOSD, your immune system malfunctions and generates inflammation continuously, even when there’s no infection to fight or injury to heal.

Researchers still don’t know exactly why this happens. Like juvenile Still’s disease (juvenile idiopathic arthritis), adult Still’s disease is idiopathic, which means the cause is unknown. It doesn’t appear to be genetic.

How is adult-onset Still’s disease diagnosed?

The symptoms of adult-onset Still’s disease resemble many other conditions. And as it’s rare, a healthcare provider might not suspect it right away. It can be a process to get to the right diagnosis.

After reviewing your symptoms and health history, your provider will order blood tests and imaging tests to learn more about your condition. Imaging tests, like X-rays or an ultrasound, can show inflammation and swelling in your joints. Blood tests can help rule out other conditions. If your blood test shows high levels of ferritin along with a high white blood cell count, these signs point to AOSD.

What is the treatment for adult-onset Still’s disease?

Healthcare providers treat adult-onset Still’s disease with various types of anti-inflammatory drugs. Different medications work better for different people. It can take some trial and error to find which ones work best to manage your symptoms. Once you do, you may need to continue taking them for a long time, even when you’re not having symptoms. This helps to keep the inflammation from building up again.

Some medications can have negative side effects if you use them too long. If you take these medications, your provider will switch them around from time to time to prevent side effects.

Medications may include:

• Nonsteroidal anti-inflammatory drugs (NSAIDs).
• Corticosteroids (synthetic steroids).
• Disease-modifying anti-rheumatic drugs (DMARDs).
• Biologics.

How serious is adult-onset Still’s disease?

In most cases, AOSD will impact your quality of life more than your long-term health. It’s uncomfortable and can interfere with day-to-day activities, but it won’t necessarily do lasting damage to your body.

However, some people do develop progressive, degenerative arthritis. This is more likely with chronic AOSD than with other types. Inflammation in your joints can cause them to deteriorate if it’s severe enough and lasts long enough. As inflammation erodes the cushioning around your joints, they can start to shift out of place. Swelling and misalignment can cause painful deformities in your joints.

Rarely, inflammatory processes related to adult-onset Still’s disease may also affect your internal organs, including your heart and lungs. This can lead to more serious complications. While AOSD alone doesn’t usually affect your life expectancy, some of these secondary conditions can rarely be fatal.

What are the serious complications of adult-onset Still’s disease?

Rare but serious complications include:

• Pericarditis.
• Myocarditis.
• Disseminated intravascular coagulopathy (DIC).
• Pulmonary arterial hypertension.
• Pleural effusion.
• Interstitial lung disease.
• Hemophagocytic lymphohistiocytosis (HLH).

Is adult-onset Still’s disease curable?

Medications can’t cure AOSD, but they can help suppress your symptoms. For some people, symptoms will eventually go away and not come back. This is called remission. If you go into remission, you can discontinue your medications. For some people, AOSD never really goes away. You may need to take medications indefinitely to keep the inflammation under control.

It’s hard to predict which prognosis you should expect. However, some healthcare providers believe that your early symptoms are a clue. If you have pain and swelling in many joints early on, it’s more likely to be longer lasting.

How should I take care of myself while living with adult-onset Still’s disease?

Many people living with adult-onset Still’s disease can have a normal and comfortable life with the right medications. Others may struggle with chronic pain and chronic fatigue that comes and goes, impacting their daily life. Whether or not the symptoms of AOSD continue to trouble you much, you might experience various side effects from your medications, including weight gain and mood changes.

When uncontrollable factors add constant stress to your life, basic self-care matters all the more. Good quality sleep, nutritious food choices and regular, low-impact exercise will help you feel better overall.