Undifferentiated inflammatory arthritis (UIA) refers to all cases of inflammatory joint disease that do not fit the criteria for a specific diagnosis. The condition may sometimes be a precursor for rheumatoid arthritis (RA).

UIA affects 41–149 per 100,000 adults. Approximately one-third to just over half of all people with the condition will develop RA.

This article explores what UIA is, remission, progression to RA, and the treatments and outlook for the condition.

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UIA is a group of inflammatory joint diseases that do not meet the criteria for a doctor to diagnose them as a specific rheumatic disorder.

A person with UIA may have swollen, painful, and tender joints, possibly indicating that they are likely to progress to RA or another specific rheumatic disease.

However, the condition does not present specific characteristics that a doctor could use to define it as one specific disorder.

For many people, UIA progresses to RA or a different rheumatic disease. In other cases, individuals experience spontaneous remission, and the condition disappears without treatment.

About 40–50% of people with UIA achieve spontaneous remission, and the symptoms recede without needing treatment.

Some individuals achieve remission with treatment, which typically involves disease-modifying antirheumatic drugs (DMARDs).

A long-term study found that 57–61% of people with UIA achieved sustained remission either spontaneously or after treatment with DMARDs.

Once UIA has progressed to RA, it is rare for someone to achieve spontaneous remission. However, a person with RA can achieve remission with treatment.

The frequency of remission in RA is about 20% but can be as high as 50–70% when doctors use a treat-to-target strategy. This treatment strategy sets remission as the goal of treatment and measures the patient’s progress frequently.

A person is more likely to be in remission if they receive treatment in the early stages of RA.

UIA progresses to RA in 13–54% of cases.

RA is a chronic autoimmune disease that causes inflammation, pain, swelling, and tenderness in the joints.

The condition can lead to disability, joint damage, and complications such as lung disease, anemia, and inflammation of the airways and blood vessels.

Treatment may be more successful if a person receives a diagnosis in the early stages of the disease.

Research has found that those who receive a diagnosis more than 12 weeks after the onset of symptoms experience more severe joint damage.

To treat UIA, a doctor may assess someone to determine if they have risk factors for RA or other forms of arthritis. These can include the presence of certain antibodies and inflammatory markers.

If a person has one or more high risk features, a doctor may treat the condition with DMARDs, which can include:

A doctor may also prescribe steroid medications and nonsteroidal anti-inflammatory drugs (NSAIDs) for short-term use or flare-ups.

A doctor may also advise a person on nonmedical factors which can help treat UIA, such as:

  • reaching or maintaining a moderate weight
  • lifestyle modifications such as eating a balanced, nutritious diet and exercising regularly
  • maintaining dental hygiene
  • stopping smoking, if applicable

The outlook for UIA varies — 40–50% of people may achieve spontaneous remission, and up to 61% may achieve remission after treatment with DMARDs.

In 13–54% of people, UIA progresses to RA. The outlook for rheumatoid arthritis is typically more favorable when a person receives treatment in the early stages.

Undifferentiated inflammatory arthritis (UIA) is a group of inflammatory joint diseases that do not meet the criteria for diagnosis as specific rheumatic diseases.

UIA progresses to rheumatoid arthritis in approximately one-third to just over half of all cases.

In 40–50% of cases, people with UIA achieve spontaneous remission. The likelihood of remission may improve with treatment.

A doctor may treat UIA with a combination of DMARDs, steroid medications, and NSAIDs.