People with undifferentiated arthritis have symptoms similar to those of inflammatory arthritis — joint swelling, pain, and stiffness — and are at risk of developing a rheumatic disease.

Arthritis is a group of conditions that affect your joints. It’s estimated that 23.7% of people in the United States have received a diagnosis of some form of arthritis.

There are more than 100 known types of arthritis. One of these types is called undifferentiated arthritis (UA).

With UA, you have signs and symptoms of inflammatory arthritis, but you don’t meet the diagnostic criteria of these conditions. Some people with UA develop rheumatoid arthritis (RA) or another rheumatic disease.

This article takes a closer look at the symptoms, risk factors, diagnosis, and treatment of UA.

The symptoms of UA are consistent with those of inflammatory arthritis and can include:

It’s important to note that the symptoms above are also common to specific types of inflammatory arthritis, such as RA, or to other rheumatic diseases.

If you have UA, you don’t meet the specific diagnostic criteria for these conditions. That’s why UA is called undifferentiated arthritis.

Diagnostic criteria are sets of signs, symptoms, and test results that help a doctor diagnose a specific health condition.

Is undifferentiated inflammatory arthritis a disability?

According to the Centers for Disease Control and Prevention (CDC), a disability is any condition that affects your body or mind and makes it difficult for you to do some daily activities or interact with your environment.

Under this definition, arthritis, including UA, can be considered a disability. UA can lead to pain, reduced range of motion, and loss of mobility. These can all significantly affect daily life, including at home, at work or school, and when you’re out and about.

If UA significantly affects your daily life and ability to work, you may be eligible for disability benefits from the Social Security Administration (SSA).

Learn more about eligibility for disability benefits from the SSA.

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It’s unknown what exactly causes UA. In general, inflammatory arthritis happens when your immune system mistakenly attacks healthy joint tissue, leading to inflammation and damage in the affected joints.

Some of the general risk factors for inflammatory arthritis include:

  • family history or genetics
  • previous infections
  • environmental factors
  • extreme physical or emotional stress

One of the main worries with UA is the development of RA or another rheumatic disease.

Roughly one-third of people with UA go on to fulfill the diagnostic criteria for RA or another type of rheumatic disease.

RA is associated with a variety of complications, which can include:

If you receive a UA diagnosis and are at a higher risk of developing RA or another rheumatic disease, your doctor may initiate treatment to help prevent that from occurring.

UA doesn’t meet diagnostic criteria of specific types of inflammatory arthritis or other rheumatic diseases.

As such, the diagnosis of UA is a diagnosis of exclusion. That means that your doctor must rule out other conditions before making a UA diagnosis.

Medical history and physical exam

Your doctor will start by collecting a thorough medical history. They’ll ask about:

  • your symptoms, how long you’ve had them, and how severe they are
  • whether or not you have a family history of inflammatory arthritis or rheumatic disease
  • any other health conditions you’ve been diagnosed with
  • the types of medications and supplements that you’re taking

Then they’ll do a physical exam, during which they’ll examine your joints. They may also check to see how your symptoms affect the movement of the affected joints.

Blood tests

In addition to your medical history and physical exam, blood tests are important for making a UA diagnosis and can include:

Imaging tests

Imaging helps your doctor better visualize your joints and look for signs of damage.

Imaging tests can include:

If you have UA and are at an increased risk of developing RA or another rheumatic disease, your doctor will initiate treatment. This typically involves prescription medications that aim to reduce inflammation and disease activity.

Some of the factors that may be considered when assessing your risk include:

  • whether or not you have a family history of RA or another rheumatic disease
  • the number and locations of affected joints
  • if you have high levels of inflammatory markers such as CRP and ESR
  • if you have markers associated with RA, such as RF and anti-CCP
  • whether or not you already have signs of joint damage
  • your age and overall health

Treatment for UA typically includes disease-modifying antirheumatic drugs (DMARDs). These drugs target the inflammatory process, with the aim of lowering inflammation, reducing symptoms, and preventing the progression of UA.

Examples of the DMARDs that may be prescribed for UA include:

If you have a flare of your UA symptoms, you may also be prescribed corticosteroids. These drugs are generally prescribed on a short-term basis to lower inflammation in your body.

Generally speaking, there are three potential outcomes of UA. These include:

  • continuation of UA as diagnosed
  • development of RA or another rheumatic disease
  • remission

A 2023 study of 203 people with UA found that most people’s UA continued as diagnosed. Researchers observed that 20.7% of people experienced remission, while 11.8% developed RA or another rheumatic disease.

Receiving treatment with DMARDs may delay or prevent the development of RA. One 2018 study found that treatment of UA with DMARDs, especially methotrexate, was associated with reduced development of RA at 12 months.

However, the researchers didn’t see a significant effect of treatment at 30 or 60 months. This suggests that for some people, treatment can delay the development of RA but not entirely prevent it.

People with UA have symptoms of inflammatory arthritis. However, they don’t meet the diagnostic criteria of RA or other rheumatic diseases. It’s unknown what exactly causes UA and other types of inflammatory arthritis.

In order to diagnose UA, your doctor will have to rule out other specific conditions. They’ll do this using your medical history, a physical exam, blood tests, and imaging.

People with UA can go on to develop RA or another rheumatic disease. If you’re at a high risk, your doctor will likely initiate treatment to help prevent or delay this from happening.