Psoriatic Arthritis

Doctor Helping Patient

Fast Facts

  • Psoriatic arthritis is a chronic arthritis. In some people, it is mild, with just occasional flare ups. In other people, it is continuous and can cause joint damage if it is not treated. Early diagnosis is important to avoid damage to joints.
  • Psoriatic arthritis typically occurs in people with skin psoriasis, but it can occur in people without skin psoriasis, particularly in those who have relatives with psoriasis.
  • Psoriatic arthritis typically affects the large joints, especially those of the lower extremities, distal joints of the fingers and toes, and also can affect the back and sacroiliac joints of the pelvis.
  • For most people, appropriate treatments will relieve pain, protect the joints, and maintain mobility. Physical activity helps maintain joint movement.
  • Psoriatic arthritis is sometimes misdiagnosed as gout, rheumatoid arthritis or osteoarthritis.

Psoriatic arthritis is an inflammatory arthritis that is seen in association with skin psoriasis. It causes joint pain and swelling that can lead to damage of the joint if the inflammation is not controlled. Joint damage can be prevented with the appropriate medications. Skin psoriasis is a scaly red skin lesion that occurs on the extensor aspects of the body (elbows, knees, scalp). Usually psoriatic arthritis is blood test negative. The diagnosis is typically made by a rheumatologist after reviewing a clinical history and performing a physical exam. X-ray studies can show changes specific to psoriatic arthritis but these are rarely present at the onset of symptoms. It is estimated about 15 – 30 percent of patients with skin psoriasis will develop an associated arthritis. At times, the arthritis can appear before the skin disorder.

Psoriatic arthritis usually appears in people between the ages of 30 to 50, but can begin as early as childhood. Men and women are equally at risk. Children with psoriatic arthritis are also at risk to develop uveitis (inflammation of the middle layer of the eye). Approximately 15 percent of people with psoriasis develop psoriatic arthritis. At times, the arthritis can appear before the skin disorder.

What is psoriatic arthritis?

Psoriasis and psoriatic arthritis are autoimmune conditions. An autoimmune condition occurs when the body's immune system mistakenly sends inflammation to normal tissue/structures. In skin psoriasis, the inflammation is mistakenly directed toward the skin. In psoriatic arthritis, the inflammation is directed toward the joints, similar to rheumatoid arthritis, causing inflammation (swelling, redness, pain and stiffness) and damage. Like any autoimmune condition, psoriasis and psoriatic arthritis can present across a broad spectrum from mild to severe disease. There is a weak relationship between the severity of skin disease and arthritic involvement. Some patients may have severe skin disease and no arthritis and some arthritis patients may have only minimal skin disease.

Psoriatic arthritis can affect any joint in the body, and it may affect just one joint, several joints or multiple joints. For example, it may affect one or both knees. Affected fingers and toes can resemble swollen sausages, a condition often referred to as dactylitis. Finger and toe nails also may be affected with thickening or nail pitting. Psoriatic arthritis in the spine, called spondylitis, causes pain in the back or neck, and difficulty bending. Psoriatic arthritis also can cause tender spots where tendons and ligaments join onto bones. This condition, called enthesitis, can result in pain at the back of the heel, the sole of the foot, around the elbows or in other areas. Enthesitis is one of the characteristic features of psoriatic arthritis.

Recent research suggests that persistent inflammation from psoriatic arthritis causes joint damage later, so early accurate diagnosis is essential. Fortunately, treatments are available and effective for most people.

What causes psoriatic arthritis?

What causes psoriatic arthritis is not known exactly. About 40 percent of patients with psoriasis or psoritaic arthritis have a family member with psoriasis or arthritis, suggesting heredity may play a role. Psoriatic arthritis can also result from an infection that activates the immune system. There are theories that an infection could trigger an autoimmune condition in a person with the right genetic background, but this has not been definitively proven.

How is psoriatic arthritis diagnosed?

To diagnose psoriatic arthritis, rheumatologists look for swollen and painful joints, certain patterns of arthritis, and skin and nail changes typical of psoriasis. X-rays often are taken to look for joint damage. MRI, ultrasound or CT scans can be used to look at the joints in more detail.

Typically blood tests are negative in psoriatic arthritis. Blood tests may be done to rule out other types of arthritis that have similar signs and symptoms, including gout, osteoarthritis and rheumatoid arthritis. Inflammation markers can be elevated in psoriatic arthritis but are commonly normal. The presence of an HLA-B27 genetic marker is associated with psoriatic arthritis but it is not diagnostic. Occasionally skin biopsies (small samples of skin removed for analysis) are needed to confirm the psoriasis.

How is psoriatic arthritis treated?

Medications are used to reduce inflammation caused by arthritis reducing pain, swelling and stiffness. Many of the medications suppress the immune system and lead to a potential increase risk of infections. The majority of the medications treat both the skin and joint disease, but some medications may work better for one compared to the other. Non-steroidal anti-inflammatory drugs such as ibuprofen (Motrin or Advil) or naproxen (Aleve) are the initial treatment for very mild arthritis. These do not help skin psoriasis. Non-steroidal anti-inflammatory medications have not been proven to stop damage caused by more aggressive/severe psoriatic arthritis.

If the arthritis does not respond, disease modifying anti-rheumatic drugs may be prescribed. These include sulfasalazine (Azulfidine), methotrexate (Rheumatrex, Trexall, Otrexup, Rasuvo), cyclosporine (Neoral, Sandimmune, Gengraf) and leflunomide (Arava). Although these medications can be very helpful with improving both skin and joint disease, they have not been proven to stop the progression of joint damage radiographically. If joint damage is present at time of diagnosis, consider increasing therapy to include biologic therapy.

Older DMARD therapies that are less commonly used today due to the development of biologic therapies are sulfasalazine (Azulfidine), Azathioprine (Imuran), and the anti-malarial drug hydroxychloroquine (Plaquenil). It was once thought Hydroxychloraquine would flare skin psoriasis but this has not been proven.

Newer biologic therapy has been developed to block molecules and/or their receptors leading to decreased inflammation. Many of these medications are given by injections at home or by an infusion at the doctor’s office. These medications suppress the immune system to a great degree compared to the DMARDs. They have been proven to stop joint damage as well as pain and swelling in moderate to severe psoriatic arthritis. They are very good at clearing skin psoriasis. The biologic therapies include anti-tumor necrosis factor (anti-TNF) drugs such as adalimumab (Humira), etanercept (Enbrel), golimumab (Simponi), certolizumab (Cimzia) and infliximab (Remicade) are also available and can help the arthritis as well as the skin psoriasis. Other biologic therapies include ustekinumab (Stelara) which blocks two proteins IL-12 and IL-23. This is given as a subcutaneous injection every 3 months. The newest biologic to be FDA approved (in January of 2016) is secukinumab (Cosentyx) which blocks IL-17 to reduce inflammation. It is given by a subcutaneous injection and has been approved for treatment of both skin psoriasis and psoriatic arthritis.

Apremilast (Otezla) is a phosphodiesterase 4 inhibitor that helps stop inflammation. It is an oral pill taken twice daily. Unlike the other treatments, it is not thought to suppress the immune system causing increased risk on infections. Stomach upset, headache, weight loss and worsening depression are potential side effects.

For swollen joints, corticosteroid injections can be useful. Surgery can be helpful to repair or replace badly damaged joints.

Broader health impact of psoriatic arthritis

The impact of psoriatic arthritis depends on the joints involved and the severity of symptoms. Ocular inflammation, including uveitis and conjunctivitis, occurs in some patients with psoriatic arthritis. Some psoriatic arthritis patients also experience mood changes. Treating the arthritis and reducing the levels of inflammation helps with these problems. People with psoriasis are slightly more likely to develop high blood pressure, high cholesterol, obesity or diabetes. Maintaining a healthy weight and treating high blood pressure and cholesterol are also important aspects of treatment.

Living with psoriatic arthritis

Many people with arthritis develop stiff joints and muscle weakness due to lack of use. Proper exercise is very important to improve overall health and keep joints flexible. This can be quite simple. Walking is an excellent way to get exercise. A walking aid or shoe inserts will help to avoid undue stress on feet, ankles, or knees affected by arthritis. An exercise bike provides another good option, as well as yoga and stretching exercises to help with relaxation.

Some people with arthritis find it easier to move in water. If this is the case, swimming or walking laps in the pool offers activity without stressing joints. Many people with psoriatic arthritis also benefit from physical and occupational therapy to strengthen muscles, protect joints from further damage, and increase flexibility.

The rheumatologist's role in the treating psoriatic arthritis

Psoriatic arthritis is easy to confuse with other diseases. As specialists in musculoskeletal disorders, rheumatologists are more likely to make a proper diagnosis. They also can advise patients about the best treatment options.

Updated September 2013. Written by Paul Emery, MD, and Zoe Ash, MD, and reviewed by the American College of Rheumatology Committee on Communications and Marketing.

This information is provided for general education only. Individuals should consult a qualified health care provider for professional medical advice, diagnosis and treatment of a medical or health condition.

© 2013 American College of Rheumatology