Psoriatic arthritis is a form of arthritis (joint inflammation) that can occur in people who have psoriasis (scaly red and white skin patches).
What happens in psoriatic arthritis?
Psoriatic arthritis affects the joints, and areas where muscles and ligaments attach to bone. Typically, skin disease precedes the arthritis, sometimes by several years. In some cases, arthritis occurs first.
The joints most commonly affected are:
- The outermost joints of the fingers or toes.
- Lower back.
Anyone can be affected by psoriatic arthritis, but certain risk factors are associated with a greater risk for the disease:
- Race: Psoriatic arthritis is more common in Caucasians than African Americans or Asian Americans.
- Age: The disease typically begins between the ages of 30 and 50, but can begin in childhood.
Symptoms of psoriatic arthritis include:
- Joint pain and swelling that may come and go and may be accompanied by redness and warmth.
- Tenderness where muscles or ligaments attach to the bones, particularly the heel and bottom of the foot.
- Inflammation of the spinal column, called spondylitis, which can cause pain and stiffness in the neck and lower back.
- Morning stiffness.
- Reduced range of motion of the joints.
- Painful, sausage-like swelling of the fingers and/or toes.
- Thickness and reddening of the skin with flaky, silver white patches called scales.
- Pitting of the nails or separation from the nail bed.
- Pink eye, inflammation, or infection of the membrane lining the eyelid and part of the eyeball.
No one knows what causes psoriatic arthritis. People with the condition often have a family member with psoriasis or arthritis, suggesting that genetics are involved. In people with the disease gene, an infection may activate the immune system to trigger the development of psoriatic arthritis. This indicates that environment is also involved.
If you have psoriasis and start to develop joint pain, it’s important to see your doctor. Early diagnosis and treatment of psoriatic arthritis can help prevent joint damage.
Although there is no test for psoriatic arthritis, your doctor may do the following to diagnosis you with the condition:
- Ask you about your medical and family history.
- Give you a physical exam.
- Take samples of blood or joint fluid for a laboratory test.
- Take x-rays.
Treatment for psoriatic arthritis depends on its severity. Milder forms of the disease may be treated by:
- Nonsteroidal anti-inflammatory drugs (NSAIDs) are used to treat pain and inflammation. Ibuprofen and naproxen sodium, are available over the counter, whereas other NSAIDS are available by prescription only.
- Corticosteroids, strong inflammation-fighting drugs, may be injected directly into the affected joint(s).
Forms of the disease that are persistent or affect multiple joints may be treated by:
- Disease-modifying anti-rheumatic drugs (DMARDs) that slow or stop the immune system from attacking the joints and causing damage.
- Anti-tumor necrosis factor (TNF) agents.
Doctors who diagnose and treat psoriatic arthritis include:
- A general practitioner, such as your family doctor.
- A rheumatologist, who specializes in arthritis and other diseases of the bones, joints, and muscles.
Scientists are conducting research to better understand and find better treatments for psoriatic arthritis. Some promising areas of research include:
- Genetics: Identifying genes that increase the risk of psoriatic arthritis will help scientists unlock the secrets of this troubling disease and identify targets for better therapies.
- Biologic therapies that block the inflammatory cytokine TNF are among the most effective therapies for psoriatic arthritis. A number of other agents are currently being explored.
- Vitamin D: Studies have shown that vitamin D insufficiency is common in people with psoriatic arthritis. Investigators supported by the NIAMS are studying the effects of vitamin D supplementation, along with marine omega-3 fatty acid and docosahexaenoic acid (DHA), on incidence, inflammation, and chronic pain in autoimmune diseases including psoriatic arthritis.
- Risk factors: Scientists are looking into factors that predict risk of arthritis among people with psoriasis, to better understand and treat psoriatic arthritis.
- Diagnostics: The similarity between psoriatic arthritis and other inflammatory forms of arthritis can delay an accurate diagnosis, particularly when the arthritis precedes the skin disease. Researchers, looking for better ways to diagnose the disease discovered that a technique called contrast-enhanced MRI may help doctors differentiate between rheumatoid arthritis and psoriatic arthritis in the hand and wrist, enabling them to target therapies to each condition.