OVERVIEW

What is Adult-Onset Still's Disease?

Still's disease refers to a systemic idiopathic arthritis that can occur in infants and young children (systemic juvenile idiopathic arthritis) or in adults (adult-onset Still's disease).

The cause of the disease is unknown. Patients typically present with prolonged high fever, sore throat, rash, and joint pain. Severe cases may also involve damage to other organs.

What’s the Difference Between Adult-Onset Still's Disease and Juvenile Still's Disease?

• Juvenile Still's disease, now called "systemic juvenile idiopathic arthritis," primarily involves joint symptoms and can often be controlled with nonsteroidal anti-inflammatory drugs (NSAIDs).

• Adult-onset Still's disease, in addition to joint symptoms, is more likely to cause damage to organs outside the joints, making treatment more complex.

Is Adult-Onset Still's Disease Common?

No, it is rare.

SYMPTOMS

What are the manifestations of adult-onset Still's disease?

• Fever: The most common and earliest symptom. Patients typically experience a sudden spike in temperature in the evening, reaching above 39°C, which may normalize by morning without antipyretics. Fever can persist for a week or longer.
• Sore throat: One of the earliest symptoms, more pronounced during fever, often accompanied by swollen and tender neck lymph nodes and enlarged tonsils.
• Rash: Most patients develop a rash, typically salmon-pink macules or maculopapules, mainly on the trunk, limbs, face, and neck. The rash appears during fever and fades afterward, usually without leaving marks.
• Joint pain: Nearly all patients experience joint pain, most commonly in the knees and wrists, followed by ankles, shoulders, elbows, and small hand joints. Early-stage pain occurs during fever with minimal joint damage, but late-stage disease may lead to joint destruction.
• Muscle pain: Many patients report varying degrees of muscle soreness in limbs during fever, with some experiencing muscle weakness.
• Lymphadenopathy: Swollen lymph nodes may appear during fever and shrink after temperature normalizes.
• Hepatosplenomegaly: About 1/3 of patients have enlarged livers, while over half exhibit mild-to-moderate spleen enlargement.
• Other organ damage: Including cardiac, pulmonary, or renal impairment; hematologic disorders; central/peripheral neuropathy; disseminated intravascular coagulation; and ocular inflammation.

What organ damage (complications) may accompany adult-onset Still's disease?

• Joint destruction: Primarily affects knees and wrists, but may also involve neck, feet, fingers, and hips.
• Cardiac inflammation: Pericarditis or myocarditis, potentially impairing heart function.
• Pleuritis: Pleural effusion may compress lungs, causing breathing difficulties.

CAUSES

What is the cause of adult-onset Still's disease?

The exact cause of adult-onset Still's disease remains unclear, but it may be related to genetics, infections (including streptococcus, staphylococcus, influenza virus, rubella virus, EB virus, Mycoplasma pneumoniae, etc.), and immune factors.

Who is more likely to develop adult-onset Still's disease?

• The incidence rate is roughly equal between men and women, but pregnancy and childbirth may increase the risk.
• The disease has two peak age ranges for onset: 15–25 years and 36–46 years.

DIAGNOSIS

What tests are needed to diagnose Adult-Onset Still's Disease?

• Complete Blood Count (CBC): Most patients show significantly elevated white blood cell counts (exceeding 15×10^9/L), with neutrophils accounting for over 90%. Anemia and increased platelet counts may also occur.
• Serum Ferritin: Often markedly elevated in patients, useful for assessing disease activity and treatment efficacy.
• Erythrocyte Sedimentation Rate (ESR) and C-Reactive Protein (CRP): Nearly all patients exhibit significantly elevated ESR, while CRP shows mild to moderate increases. These markers help evaluate disease activity and treatment response.
• Fibrinogen: May be elevated in some patients.
• Liver Function Tests: Some patients show elevated ALT and AST levels.
• Immunological Markers (e.g., ANA, Rheumatoid Factor): Typically negative. These tests primarily exclude other rheumatic diseases.
• Pathogen Testing (e.g., blood cultures, throat swabs): Negative in Adult-Onset Still's Disease. Used to rule out infectious causes of fever and sore throat.
• Other Tests (e.g., bone marrow aspiration, lymph node biopsy, chest X-ray, abdominal/gynaecological ultrasound, CT scans, tumour markers, bone scans, endoscopy): Aim to exclude malignancies.

Which diseases is Adult-Onset Still's Disease easily confused with? How to differentiate?

• Infectious Diseases: Such as sepsis, abscesses, and certain viral infections.
• Malignancies: Including leukemia, lymphoma, and immunoblastic lymphadenopathy.
• Other Rheumatic/Immune Disorders: Like systemic lupus erythematosus, rheumatoid arthritis, Sjögren's syndrome, mixed connective tissue disease, and vasculitis.
• Others: Such as sarcoidosis or Crohn’s disease.

Doctors differentiate these conditions by detailed medical history review and necessary diagnostic tests.

TREATMENT

How to treat adult-onset Still's disease?

• Medication: Commonly used drugs include the following.
  • Nonsteroidal anti-inflammatory drugs (NSAIDs): Such as naproxen, ibuprofen, diclofenac, celecoxib, etc. After symptoms improve, continue treatment for 1–3 months before gradually tapering the dose. Regular blood tests, liver and kidney function monitoring, and attention to adverse effects are required during treatment.
  • Corticosteroids: Such as methylprednisolone, prednisone, etc. After the condition stabilizes, continue treatment for 1–3 months before gradually reducing the dose, then maintain the lowest effective dose.
  • Disease-modifying antirheumatic drugs (DMARDs): Such as methotrexate, leflunomide, hydroxychloroquine, azathioprine, sulfasalazine, cyclosporine, cyclophosphamide, etc. DMARDs are recommended for patients with poor response to corticosteroids, significant arthritis, severe organ damage, or intolerance to steroid side effects. Methotrexate is the first choice.
  • Biologics: Such as infliximab, etanercept, tocilizumab, etc. Biologics are suitable for refractory, recurrent, severe cases, organ damage, or chronic arthritis.
  • Herbal extracts: Such as total glucosides of peony, Tripterygium wilfordii, sinomenine, etc.
  • Immunoglobulin: Used for severe cases.
• Surgery:
  • Patients with arthritis should undergo regular X-rays of affected joints. If joint erosion, destruction, or deformity occurs, surgical options such as arthroplasty, soft tissue release/repair, or joint fusion may be considered. Medication must be continued post-surgery.

What precautions should be taken when using corticosteroids for adult-onset Still's disease?

• Long-term corticosteroid use increases the risk of side effects such as infections, hypokalemia, osteoporosis, gastrointestinal ulcers, elevated blood sugar/lipids, cataracts, glaucoma, and psychiatric disorders.
• Corticosteroids are effective, so they should not be refused due to side effects. Doctors often prescribe gastric protectants, calcium, and potassium supplements to mitigate risks.
• Do not stop corticosteroids abruptly. Adjust the dose under medical supervision and attend regular follow-ups.

What precautions should be taken when using DMARDs for adult-onset Still's disease?

• Monitor for adverse effects and regularly check blood counts, ESR, liver, and kidney function.
• After remission, continue DMARDs at a reduced dose for an extended period to prevent relapse.

Do adult-onset Still's disease patients require antibiotics?

Antibiotics are unnecessary unless an infection is present.

However, since adult-onset Still's disease mimics bacterial infections, empiric antibiotics may be used initially. If symptoms persist without evidence of infection, discontinue antibiotics promptly.

What are the signs of improvement in adult-onset Still's disease?

Symptom resolution and normalization of blood counts, ESR, and serum ferritin indicate remission. However, treatment should continue under medical guidance to prevent relapse.

Can adult-onset Still's disease recur?

Yes.

The disease is prone to recurrence, so do not stop medication without medical advice. Maintenance therapy is essential to prevent relapses.

DIET & LIFESTYLE

What should adult Still's disease patients prepare before seeking medical attention?

• Record your symptoms, including the time of the first onset and the frequency of recurrence, as well as the timing and characteristics of fever, etc.
• Document your medical history.
• List all medications you are currently taking, as well as any drugs you have previously used to treat this condition and their effectiveness.

PREVENTION

Can Adult-Onset Still's Disease Be Prevented?

Since the cause of the disease is unknown, it is difficult to prevent.