Psoriatic Arthritis

What is Psoriatic Arthritis?

Psoriatic arthritis is a chronic (long lasting) autoimmune disease that affects the joints in association with skin or nail changes as seen in psoriasis. Psoriasis is a common, inherited skin condition that causes grayish-white scaling over a pink or dull-red skin rash.

Statistics on Psoriatic Arthritis?

Psoriasis affects 1-3% of the population. Psoriatic arthritis affects 5-8% of patients with psoriasis, so it is fairly uncommon. Men and women are equally affected. Age of onset is often between 35-55 years, but can occur at any age.

Risk Factors for Psoriatic Arthritis

The cause of psoriatic arthritis has not yet been established. Genetic influences, environmental and immunological factors are all thought to be involved.

Progression of Psoriatic Arthritis

There are at several subtypes of psoriatic arthritis, which produce a range of symptoms and affect different parts of the body.

Asymmetric arthritis: The mildest form of psoriatic arthritis, which tends to affect joints only on one side of your body or different joints on each side, particularly in the knee, ankle or wrist. Swelling and inflammation of the tendons in the hands and feet can cause fingers and toes to resemble sausages (dactylitis).
Distal interphalangeal arthritis: a minority of people with psoriatic arthritis (usually men) have this form, which affects the small joints closest to the nails (distal joints) in the fingers and toes. In addition to the arthritis, patients may also notice nail and skin changes.
Symmetrical polyarthritis: Unlike asymmetric arthritis, this form usually affects a greater number of joints and on both sides of the body. It shares similarities to rheumatoid arthritis, a common and often severe arthritic condition, however symptoms are usually milder. Psoriasis associated with this condition tends to be severe.
Arthritis mutilans: this is a rare form of psoriatic arthritis. Over time, the small bones in the hands become eroded, leading to permanent deformity and disability.
Spondylitis: occurs in a small number of patients (with a male preference). This form of psoriatic arthritis causes stiffness and inflammation in the spine, particularly in the lower back. Movement becomes increasingly painful and difficult.

There is also a type of psoriatic arthritis that affects children. Children typically develop signs and symptoms of the disease around 10 years of age. Symptoms are often mild, although some children may have severe and debilitating problems that last into adulthood.

How is Psoriatic Arthritis Diagnosed?

X-rays of affects joints may show signs of swelling, bone erosion and loss of space between joints. Deformity is normally minimal. Less commonly characteristic signs such as the pencil-in-cup deformity may be seen.

Prognosis of Psoriatic Arthritis

Traditionally, psoriatic arthritis has been considered to run a milder course and have a better prognosis than rheumatoid arthritis. However, current evidence suggests that it has the potential to be just as debilitating, posing the question as to whether a more aggressive approach to treatment should be taken. Factors such as earlier age of onset, severe skin involvement and a family history of the condition may indicate a poorer prognosis.

How is Psoriatic Arthritis Treated?

The goals of management are to improve symptoms and control joint inflammation. Often skin and joint disease needs to be treated at the same time. Initial treatment generally aims to control inflammation with anti-inflammatory medications, and skin disease with medications applied to the skin. In many patients this is sufficient to control symptoms.

For patients with more severe symptoms other approaches such as steroid injections into affected joints, or medications to suppress the immune system such as those used in rheumatoid arthritis, may be considered. New therapies are currently being researched with promising results. Surgery is not normally undertaken in psoriatic arthritis, but for patients with severe arthritis in one joint it may be effective. An exercise program is recommended for patients to maintain mobility and strength.

Psoriatic Arthritis References

Al Hammadi A. Psoriatic Arthritis. eMedicine 2004. [available online @ http://www.emedicine.com/med/topic1954.htm]
Clemens L. The role of the rheumatologist in managing arthritis.MJA 2001; 175: S97-S101.
Keat A. ABC of Rheumatology: Spondyloarthropathies. BMJ 1995;310:1321-1324.
Kumar and Clark. Clinical Medicine, 5th ed. WB Saunders, Toronto (2002).