Psoriatic Arthritis: What You Need to Know

Psoriatic arthritis is a chronic type of joint inflammation in psoriasis that may develop in 4 to 30% of people who have psoriasis.^[1,2] Psoriatic arthritis tends to develop about ten years after the person gets psoriasis. Adults between the ages 30-55 are more commonly affected, but children can also get psoriatic arthritis.^[3] Women and men are equally affected.^[4] Though any joints in the body may be affected, the most commonly affected joints are the fingers and wrists. A single joint or several joints may be affected at one time. The inflamed joints may become painful, swollen, and feel hot and stiff. Psoriatic arthritis can affect the lower spine and cause chronic low back pain in 40% of people who have psoriatic arthritis.^[5] Men are more likely to have spinal involvement than women.^[4] Additionally, the tendons around the ankles and feet may be inflamed and cause ankle and feet swelling. With time, chronic inflammation can permanently destroy the joints and cause significant disability. Therefore, early diagnosis and treatment by a health professional is important in limiting damage to the joints.

What Causes Psoriatic Arthritis?

The exact cause of psoriatic arthritis is unknown, but several factors have been linked to its development.

Genetics

Overall, research shows that the genetic makeup of a person may increase the chances of developing psoriatic arthritis. For example, people with a specific sequence in their DNA, called HLA-B27, are more likely to get certain auto-inflammatory conditions, including psoriatic arthritis.^[6] About 40% of those who have psoriasis or psoriatic arthritis have a first-degree relative with psoriasis. People who have a first degree relative with psoriatic arthritis can be 55 times more likely to get psoriatic arthritis than the general population.^[2]

Overly active immune system

An overly active immune function causes the release of molecules that cause inflammation in the skin, nails, and joints in people with psoriasis.^[7]

Infections

The timing of viral and bacterial infections has been associated with the development or worsening of psoriatic arthritis.^[8,9]

Injuries 

A few studies have suggested that physical trauma and injuries may induce psoriatic arthritis in people who also have psoriasis.^[10,11]

Can I Get Psoriatic Arthritis Without Skin Psoriasis?

Yes. In fact, up to 15 % of people can get joint inflammation in psoriasis before the skin is affected. People who have psoriatic nail changes such as pitting, ridging, cracking, and pigment changes are more likely to get psoriatic arthritis.^[12]

How Is Psoriatic Arthritis Diagnosed?

When psoriatic arthritis is suspected, a health professional may ask about health history and perform a physical examination, blood tests, and X-rays or other imaging tests to more accurately diagnose psoriatic arthritis and monitor disease progression.

How Is Psoriatic Arthritis Treated?

Just like psoriasis, there is no cure for psoriatic arthritis. The main goal for treatment is to decrease the inflammation in the joints in order to decrease the discomfort and prevent further joint damage. Unlike skin psoriasis, psoriatic arthritis cannot be treated with topical anti-inflammatory medications or phototherapy. Oral or injectable anti-inflammatory medications are needed to control the joint inflammation in psoriasis to prevent joint destruction.^[13] The most common types of medication used to treat psoriatic arthritis are:

• Nonsteroidal anti-inflammatory drugs (NSAIDS): NSAIDs such as ibuprofen, naproxen, diclofenac, indomethacin, and celecoxib may help temporarily decrease joint pain and swelling. NSAIDS are mainly used to control symptoms.^[13]
• Disease-modifying anti-rheumatic drugs (DMARD): DMARDs can help limit the amount of joint damage caused by inflammation. These medications may need to be taken for months and years. Methotrexate and leflunomide are commonly prescribed DMARDs for psoriatic arthritis.^[13]
• Biologics:  Biologics are a group of medications made from living cells cultured in the laboratory. This group of medications directly target a specific part of the immune system that causes psoriasis. Some examples of biologics used to treat psoriatic arthritis are TNF inhibitors (etanercept, infliximab, adalimumab), interleukin IL-12/IL23 inhibitors (ustekinumab), and IL-17 pathway inhibitors (secukinumab, ixekizumab, and brodalumab).^[14-16]
• Steroid Injections: Health professionals may inject corticosteroids directly into the affected joint space to treat joint inflammation.
• Joint surgery: People with severely damaged joints may be candidates for orthopedic surgery to correct or replace the affected joints. However, if the psoriatic arthritis is still ongoing, a health provider may elect to control the ongoing inflammation before surgery.