Psoriatic arthritis is a chronic inflammatory joint disease associated with psoriasis. Psoriasis can affect the joints, skin and nails, scalp, skull, spine, fingers, and toes, causing them to become inflamed and painful.

Psoriatic arthritis (PsA) appears to happen when an overactive immune system mistakenly attacks healthy tissue. However, it is not yet clear why some people with psoriasis develop PsA while others do not.

Psoriatic arthritis commonly affects the joints of the hands and feet.
Psoriatic arthritis can affect the joints of the hands and feet.

There is no definitive test for PsA.

To diagnose the condition, a doctor will:

Imaging tests for PsA can detect inflammation in the joints, and particularly the sacroiliac joints (SI joints), in the pelvis.

This information can help a doctor to make a diagnosis and rule out other possible causes.

If a doctor believes a person may have PsA, they will refer them to a rheumatologist, a specialist in joint conditions, for an assessment.

A rheumatologist will try to rule out other types of arthritis, such as rheumatoid arthritis, osteoarthritis, and gout.

They will often order the following tests to help make a diagnosis:

  • Erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) levels: These blood tests measure inflammation in the body.
  • Full blood count, kidney function and electrolytes, and liver function tests.
  • MRIs and X-rays of the affected joints: MRI and ultrasound can detect any wearing down and inflammation in joints earlier than X-rays.
  • Rheumatoid factor (RF) and anti-cyclic citrullinated peptide (CCP) antibodies: If a person has these antibodies, a doctor may consider a diagnosis of rheumatoid arthritis rather than PsA.
  • Anti-nuclear antibodies (ANA): These antibodies can be present in people with PsA.

Symptoms of PsA vary from mild to severe. Generally, people have good and bad days.

Apart from joint pain, tiredness is a common symptom of psoriatic arthritis.

On a good day, symptoms may be barely noticeable. A flare-up, on the other hand, can be extremely painful.

Usually, one or more of the following symptoms will appear:

  • general tiredness
  • tenderness, pain, and swelling over tendons
  • swollen fingers and toes
  • joint pain with swelling and stiffness
  • reduced range of movement
  • stiffness in joints in the morning
  • nail changes, including pitting of nails and separation of nails from the nail bed

People with psoriasis who experience persistent pain, swelling, or stiffness in their joints should see a doctor.

It can often take some time to get a diagnosis of PsA. During this time, the person is at risk of progressive joint damage and disability.

However, the long-term outlook for the management of PsA is good, especially if diagnosis is early and the person follows an appropriate treatment plan.

One aim of treatment is to relieve inflammation and swelling.

There are many different treatment options available for PsA, depending on how severe the condition is.

Treatment will aim to:

In 2015, two groups of experts, the and , made recommendations to help rheumatologists decide on the best course of action for managing PsA.

In general, their recommendations were as follows:

NSAIDs

The GRAPPA guidelines recommended using non-steroidal anti-inflammatory drugs (NSAIDs) as a first-line therapy for joints that are painful but not yet at risk of damage.

NSAIDs block the production of prostaglandins, which signal the body's immune system to trigger an inflammatory response.

Common over-the-counter NSAIDs are ibuprofen and naproxen sodium.

Intra-articular injection

Injecting a local corticosteroid injection into affected joints can provide temporary relief from inflammation.

Synthetic DMARDs

A doctor may introduce a disease-modifying antirheumatic drug (DMARD) to help to slow disease progression. Oral small molecule (OSM) drugs are a type of non-biologic disease-modifying therapy.

Apremilast (Otezla) is one type of OSM drug. Apremilast works by blocking an enzyme that manages immune and inflammatory processes.

Biologic DMARDs

Finally, the 2015 guidelines recommended offering a special subclass of DMARDs called tumor necrosis factor inhibitors (TNFIs) if the symptoms did not respond effectively to other DMARDs.

TNFIs work by blocking a specific protein that immune cells produce. This protein signals other cells to start the inflammatory process.

Newer biologics, such as ustekinumab (Stelara), work by blocking two proteins that cause inflammation.

Others, such assecukinumab (Cosentyx), ixekizumab (Taltz), and siliq (Brodalumab) target a different protein.