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Terms to Know When You Have Adult-Onset Still’s Disease

Reviewed by: HU Medical Review Board | Last reviewed: February 2023

Even if you have lived with adult-onset Still's disease (AOSD) for years, new terms can come up often. Whether you are new to the AOSD world or wanting to understand things you have heard in the past, it helps to get clear on the language your doctor might use. Some common AOSD-related terms that might be helpful to know are below.1-4

Adult-onset Still’s disease (AOSD): A type of arthritis caused by an overactive immune system. AOSD is different from other forms of arthritis, like osteoarthritis or rheumatoid arthritis.

Systemic juvenile idiopathic arthritis (SJIA): Also called Still’s disease. It is essentially the same disease as AOSD. The main difference is that it is diagnosed in people under the age of 16.

Arthritis: Chronic inflammation of the joints that can cause long-term damage.

Autoinflammatory disease: A disease that affects the innate immune system, the body’s first line of defense. AOSD is an autoinflammatory disease.

Autoimmune disease: A disease that affects the adaptive immune system, the body’s more specific line of defense. The adaptive immune system includes antibodies. Antibodies are proteins that target specific germs or threats to the body. Rheumatoid arthritis is a type of autoimmune disease.

Rheumatologist: A doctor who specializes in treating autoimmune or autoinflammatory diseases. They may be the doctor who diagnoses AOSD or who a person is referred to for long-term treatment planning.

Nonsteroidal anti-inflammatory drugs (NSAIDs): Drugs like aspirin and ibuprofen that decrease inflammation. NSAIDs are often sold over the counter or in stronger forms by prescription. They are the first-line treatment for mild AOSD pain or fevers.

Steroids: The next line of drug treatment for AOSD after NSAIDs. They also reduce inflammation in the body but have more side effects than NSAIDs do. Steroids can be used to help control flare-ups of symptoms quickly.

Disease-modifying antirheumatic drugs (DMARDs): Drugs that target specific steps in the body's inflammatory process. They are used to treat AOSD that has not responded to NSAIDs or steroids. Traditional DMARDs like methotrexate can have many side effects and be hard on the body. Biologics are a newer type of DMARD.

Biologics: Drugs made from living cells that target specific steps in the inflammatory process. They are often used to treat autoinflammatory and autoimmune diseases when other treatments are not working.

Cytokines: Proteins in the innate immune system that play a role in inflammation. Some increase inflammation (pro-inflammatory), while others decrease it (anti-inflammatory). People with AOSD have too many pro-inflammatory cytokines. Biologic drugs for AOSD often target these cytokines.

Flare-ups: Periods of worsening symptoms. Flare-ups can come after a period of no symptoms at all. Some people will have regular, recurring flare-ups of AOSD, while others may have more stable symptoms.

Remission: Periods where AOSD symptoms improve or disappear. Like with flare-ups, these can vary from person to person. Some people will have only one episode of AOSD symptoms and then go into remission.

Maintenance therapy: Treatment that is taken even when symptoms are not currently active. The goal of maintenance therapy is to reduce long-term damage and prevent future flare-ups.

Lymph nodes: Areas in the body where immune system cells live. Lymph nodes are all over the body, including in the neck, under the armpits, and in the groin. When the body needs to fight an infection or turn on the immune system for any reason, lymph nodes can get bigger as the cells within them activate. In people with AOSD, the lymph nodes in the neck often swell up.

Macrophage activation syndrome (MAS): A potentially life-threatening complication of AOSD. In MAS, the body’s immune system is turned up to a dangerous level. People with MAS have low blood cell counts, high levels of fat in the blood, and liver issues. One of the goals of AOSD treatment is to decrease the risk of developing MAS.

Quotidian fever: A fever that recurs in a regular, usually daily, pattern. In people with AOSD, fevers tend to happen once per day for at least 2 weeks at a time. The fevers most commonly occur in the afternoons or evenings.

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