Psoriatic arthritis is a chronic (long-lasting) disease in which a person with psoriasis develops the symptoms and signs of arthritis -- joint pain, stiffness and swelling. Psoriasis is a common, inherited skin condition that causes grayish-white scaling over a pink or dull-red skin rash.
Approximately 5% to 10% of the 3 million people who have psoriasis develop psoriatic arthritis. Psoriatic arthritis affects men and women equally and usually begins between ages 30 and 50. However, the disease can also occur in children. Most people have mild symptoms, but in some cases, the symptoms can be quite severe.
Types of Psoriatic Arthritis
There are five types of psoriatic arthritis. They are classified by their severity, whether both sides of the body are equally affected and which joints are involved.
- Asymmetric inflammatory arthritis -- Often the knee, ankle, wrist or finger are involved, with a total of one to four inflamed joints. Usually, the arthritis does not affect both sides of the body equally (that is, the disease is not symmetric).
- Symmetric arthritis -- Multiple joints are inflamed, often more than four, and the same joints on both sides of the body are affected. Fingernails often are ridged and pitted. This condition can mimic rheumatoid arthritis.
- Psoriatic spondylitis -- One or both sacroiliac joints (the joints linking the spine and pelvis at the lower back), and sometimes other spine joints, are inflamed, causing morning stiffness in the back.
- Isolated finger involvement -- This often involves only the last finger joint near the nail. One or more of these joints may be inflamed.
- Arthritis mutilans -- This is the most severe and rarest form of psoriatic arthritis. In this form, the fingers shorten because of destruction of the joints and nearby bones.
Although each type of psoriatic arthritis is somewhat distinct, some people show a blending of symptoms or have more than one type.
Psoriasis can develop before or after the arthritis, but psoriasis develops first in about 75% of cases. A person may begin to get morning joint stiffness before the arthritis is recognized. People who have psoriasis that involves the nails, especially nail pitting, are much more likely to develop arthritis than those without this problem (50% versus 10%).
The cause of psoriatic arthritis is unknown. There is some evidence that infection or trauma can play a role in the development of the disease. For example, psoriatic arthritis seems to flare up in people whose immune systems are affected by human immunodeficiency virus (HIV) infection. Also, heredity seems to play a role. Up to 40% of people with psoriatic arthritis have a family history of skin or joint disease. Certain genes seem to be involved in certain types of psoriatic arthritis. For example, the gene HLA-B27 has been associated with psoriatic spondylitis.
- A pink or dull-red, scaly skin rash occurring in patches, especially on the back of the arms, front of the legs and scalp
- Inflammation of the joints, especially in the fingers, toes or spine
- Morning joint stiffness
- Lower back pain
Psoriatic arthritis can affect other parts of the body. For example, fatigue and anemia are common in people with active psoriatic arthritis. Frequently, the arthritis is accompanied by inflammation of tendons and the spots where tendons attach to bones, such as in the heel or fingers.
Usually, a doctor can diagnose psoriatic arthritis based on your symptoms and a physical examination. In contrast to lupus or rheumatoid arthritis, autoantibodies are not usually present in the blood.
Your doctor may order X-rays of the affected joints, but X-rays don't always indicate what type of arthritis you have. In a few cases, the X-rays may give the radiologist a clue that you have psoriatic arthritis rather than rheumatoid arthritis or another type of arthritis.
Psoriatic arthritis tends to be lifelong. However, some people's symptoms vary significantly, so that it may be mild at times and more severe at other times. It's unusual for the joint problems to disappear completely.
There is no way to prevent psoriatic arthritis.
The main treatment is to take nonsteroidal anti-inflammatory drugs (NSAIDs), such as aspirin, ibuprofen (Advil, Motrin) or naproxen (Aleve, Naprosyn). Corticosteroids such as prednisone, taken by mouth, are used only occasionally, because they may cause significant side effects when taken long-term and the psoriasis tends to flare up when the drug is stopped. Occasional injections of a steroid can help when joints are severely inflamed.
When the condition is more severe, drugs such as hydroxychloroquine (Plaquenil) or methotrexate (Folex, Rheumatrex) often relieve symptoms or reduce joint inflammation. However, it is uncertain whether they protect the joints from damage. Rare reports linking hydroxychloroquine to worsening psoriasis have led some doctors to avoid this medication.
Sulfasalazine (Azulfidine), an anti-inflammatory agent used to treat inflammatory bowel disease, helps some people with psoriatic arthritis. Another anti-inflammatory medication, cyclosporine (Neoral, Sandimmune), is occasionally used. However, this medicine can damage the kidneys, so it is usually used only for people who have not responded to other treatments. Newer, injectable medicines, including adalimumab (Humira), Etanercept (Enbrel), infliximab (Remicade), and golimumab (Simponi) can be highly effective, but because they are only available by injection and are quite expensive, they are reserved for people with psoriatic arthritis that does not respond to other treatments.
When joints deteriorate despite aggressive medical therapy, your doctor may recommend surgery to reconstruct or replace the joint, especially if the pain is localized and intense and you have difficulty functioning.
Your doctor may recommend physical and occupational therapy to maintain muscle strength and the joint's range of motion. Splinting, a removable brace to immobilize an inflamed joint, may help reduce symptoms and inflammation. Exercise is important, especially for people with spondylitis because being active tends to reduce back symptoms.
Call your doctor if you have symptoms of psoriatic arthritis.
The outlook for people with this disease varies. For some, psoriatic arthritis is a minor annoyance that requires medication only at times when symptoms are worse. However, in up to 25% of people with psoriatic arthritis, the condition causes disability with severe, unrelenting joint damage over time. With appropriate therapy, the majority of people with psoriatic arthritis have good control of their pain, improved function and limited joint damage.
National Institute of Arthritis and Musculoskeletal and Skin Diseases
National Institutes of Health
1 AMS Circle
Bethesda, MD 20892-3675
American College of Rheumatology
2200 Lake Boulevard NE
Atlanta, GA 30319