Psoriatic arthritis is a type of inflammatory arthritis related to psoriasis. Approximately one-third of people with psoriasis are affected by PsA. PsA generally affects the joints and the areas where ligaments and tendons connect to bones.
Psoriatic arthritis and psoriasis are autoimmune diseases — conditions that occur when the immune system mistakenly attacks healthy tissues, such as your skin and joints. Inflammation from the body’s overreacting immune response leads to symptoms of psoriasis and PsA. Psoriatic arthritis is distinct from osteoarthritis, which is caused by the normal wear and tear of aging, rather than inflammation.
PsA is caused by several complex contributing factors. Researchers have identified dozens of genetic variants that may make a person more likely to develop psoriasis and PsA.
Most scientists believe that genetics and environmental factors both contribute to PsA, but they’re still working to understand exactly why a person develops the condition. Researchers theorize that environmental factors — a physical injury, a virus, or an infection like strep throat — may trigger the development of PsA in some people. These are all situations that set off an immune response.
Having psoriasis is the primary risk factor for developing psoriatic arthritis. Psoriatic arthritis affects about 30 percent of people with psoriasis, according to the National Psoriasis Foundation. PsA usually develops in people between the ages of 30 and 50. However, not everyone with PsA receives a psoriasis diagnosis first. Between 10 percent and 15 percent of people with PsA experience joint symptoms without ever having skin symptoms.
Having a family history of psoriasis or psoriatic arthritis is another risk factor — 40 percent of people with PsA have a family history of psoriatic disease, according to the American College of Rheumatology. Whereas being female is sometimes a risk factor for other autoimmune diseases, being a particular sex doesn’t appear to be a risk factor for PsA.
Your dermatologist or primary care physician may refer you to a rheumatologist if you have symptoms of psoriatic arthritis. A rheumatologist is trained to diagnose and treat joint and tendon symptoms, while a dermatologist is focused on the skin symptoms of psoriasis and other skin conditions. Early diagnosis and treatment of PsA are associated with better outcomes.
A rheumatologist will conduct a physical exam and take a medical history. Your doctor will check to see if your joints are swollen or tender. They will likely pay special attention to the fingers and toes. They may then recommend various tests to look for signs of PsA and to rule out other possible causes.
There isn’t one simple test for diagnosing psoriatic arthritis. A rheumatologist will need to evaluate several factors before giving a diagnosis. A final diagnosis will be based on your symptoms and the results of various tests.
A rheumatologist may order an imaging test to look for signs of psoriatic arthritis. X-rays are most effective at diagnosing later-stage PsA. They’re not generally effective at detecting early-stage PsA. They can detect severe bone changes that indicate PsA.
Ultrasound and magnetic resonance imaging (MRI) may also be used to identify inflammation of joints and tendons.
No specific blood test can confirm a PsA diagnosis. Instead, blood tests are used to detect inflammation and rule out other types of arthritis. Below are some types of blood tests your doctor may order:
Biopsies are sometimes used to help confirm a diagnosis of PsA or rule out other conditions. Your doctor may perform the following types of procedures:
Learn more about psoriatic arthritis diagnosis and tests.
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Psoriatic arthritis is characterized by joint pain, swelling, and stiffness. PsA symptoms may be mild or have a severe impact on quality of life.
Also referred to as “sausage digits,” dactylitis is painful swelling in the fingers and toes. It’s often the first symptom of PsA.
People with PsA may have enthesitis, a condition characterized by pain or tenderness where ligaments and tendons attach to bone. Enthesitis most frequently occurs in the heels and bottoms of the feet, though it can also affect the elbows.
White spots, flaking, pitting (shallow or deep dents on your nails), or lifting of the nail bed may also be symptoms of psoriatic arthritis. Up to 90 percent of people with PsA experience nail changes, according to CreakyJoints.
Read more about nail symptoms of PsA.
Itchy, scaly, red, purple, or silvery lesions appear prior to the onset of psoriatic arthritis in approximately 75 percent of people with PsA, according to DermNet NZ. Skin disease can appear 10 to 20 years before developing joint symptoms, notes John Hopkins Arthritis Center.
Not all PsA symptoms affect the skin and joints. Other possible symptoms include uveitis (inflammatory eye condition) and fatigue.
Read more about symptoms of psoriatic arthritis.
Psoriatic arthritis can be broken into five categories defined by the impacted joints. It’s possible to have more than one type of PsA.
An estimated 35 percent of people with psoriatic arthritis have this type. Asymmetric oligoarthritis typically involves five or fewer joints. It’s known as asymmetric arthritis because it typically doesn’t affect both sides of the body in the same place. For example, it might appear in only one knee or one elbow.
Symmetric polyarthritis is one of the most common types of psoriatic arthritis — half of all people with PsA are estimated to have this type. Symmetric polyarthritis affects five or more corresponding joints on both sides of the body. This type of PsA is similar to rheumatoid arthritis, but it can be differentiated by a few factors, including a negative RF blood test.
Psoriatic arthritis that affects the lower back and spine is a type of spondylitis (also called spondyloarthritis). About 5 percent of people with PsA have spondylitis.
Distal arthritis causes inflammation and stiffness in the distal interphalangeal joints, those closest to the tips of fingers and toes. According to Cleveland Clinic Center for Continuing Education, this type affects about 10 percent of people with PsA, usually men. Nail changes are also common with distal arthritis.
Arthritis mutilans is the rarest and most severe type of psoriatic arthritis. This form of PsA attacks joints in the hands and feet, causing deformities and impaired movement.
While there is currently no cure for psoriatic arthritis, treatment options can control disease activity and reduce painful symptoms. Goals for PsA treatment include reducing pain and inflammation and protecting joint mobility.
Disease-modifying antirheumatic drugs (DMARDs) reduce joint and tissue damage and slow psoriatic arthritis disease progression. Older DMARDs include methotrexate, sulfasalazine, leflunomide (sold as Arava), and cyclosporine. Newer DMARDs, such as apremilast (Otezla), affect certain parts of the immune system involved in inflammation.
Biologic DMARDs work against specific proteins that cause inflammation. Tumor necrosis factor (TNF) inhibitors are biologic DMARDs that block certain proteins that maintain inflammation. Adalimumab (Humira) is one of the most common TNF inhibitors prescribed for PsA. Others include etanercept (Enbrel), infliximab (Remicade), and golimumab (Simponi).
Targeted synthetic DMARDs are now available to treat PsA. These drugs are Janus kinase (JAK) inhibitors — they block the JAK enzyme, which is often activated in autoimmune disorders. These drugs can also block PsA disease progression. The JAK inhibitors approved by the U.S. Food and Drug Administration (FDA) for psoriatic arthritis are tofacitinib (Xeljanz) and upadacitinib (Rinvoq).
Nonsteroidal anti-inflammatory drugs (NSAIDs) such as ibuprofen (sold under the brands Advil or Motrin) can reduce swelling and pain. They’re typically prescribed for mild cases of psoriatic arthritis without joint damage.
Corticosteroids can also be used to treat PsA symptoms. Corticosteroids can be given as an injection to treat inflammation in a specific joint. Oral corticosteroids can be used to treat a PsA flare, though they may exacerbate psoriasis. Long-term use of steroids is generally discouraged due to side effects.
Physical therapy can help manage psoriatic arthritis. In cases of severe joint damage, surgery may be appropriate. Lifestyle changes like eating a healthy diet and quitting smoking can also help.
When someone has more than one health condition at the same time, the conditions are known as comorbidities. Cardiovascular disease is the most common comorbidity for people with PsA. Diabetes, obesity, and nonalcoholic fatty liver disease are other conditions that many people have in addition to PsA.
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