About 10-30% of people with psoriasis will develop psoriatic arthritis. Like psoriasis, the symptoms of psoriatic arthritis can range from mild to severe.
Symptoms of psoriatic arthritis include the following:
- Stiffness, pain, and swelling of the tendons and joints
- Less mobility in affected parts of the body
- Swelling of the fingers and toes (dactylitis)
- Morning stiffness
- Generalized fatigue
The joints most commonly affected are in the fingers and toes (usually the "distal" joints at the ends), the lower back, wrists, knees, and ankles.
Most people with psoriasis do not develop arthritis symptoms until they are 30-50 years old, and they usually experience psoriasis on their skin well before the onset of joint symptoms. However, about 15% of people may develop joint symptoms BEFORE developing the classic skin lesions of psoriasis.
EARLY DIAGNOSIS AND TREATMENT OF PSORIATRIC ARTHRITIS IS IMPORTANT TO MINIMIZE THE DAMAGE TO THE JOINTS.
Types of Psoriatic Arthritis
Psoriatic arthritis may be categorized by how many joints are affected, which also reflects its severity.
- "Localized" psoriatic arthritis describes cases when only a few joints are affected. Symptoms are generally mild and may even disappear for periods of time.
- "Generalized" psoriatic arthritis describes cases when 3 or more joints are affected and symptoms are generally more severe. People with generalized psoriatic arthritis have symptoms associated with greater inflammation, such as fatigue. Generalized psoriatic arthritis is more likely to lead to long-term joint damage and disability and, as a result, is treated more aggressively.
Psoriatic arthritis may also be categorized into five "types" that describe different ways the joints are affected.
- Asymmetric arthritis affects one or more joints, such as the hip, knee, or wrist, but does not affect the same joint on the other side of the body. This form of arthritis is generally mild though the joints may become red and warm to the touch. The fingers and toes may have become thickened in a way that is described as sausage-like.
- Symmetric arthritis affects pairs of joints on both sides of the body. This tends to be more disabling than asymmetric arthritis.
- Distal interphalangeal predominant (DIP) involves the distal joints of the fingers and toes. Changes to the toenails or fingernails can usually be seen.
- Spondylitis causes stiffness and pain in the neck and lower back. Spondylitis affects about 5% of those with psoriatic arthritis.
- Arthritis mutilans is a destructive form of arthritis with a high risk of causing disability. It affects less than 5% of those with psoriatic arthritis.
Diagnosis of Psoriatic Arthritis
There is no single test that can prove whether someone has psoriatic arthritis or not. The diagnosis requires a physical exam, medical history, and a variety of medical tests that help to confirm psoriatic arthritis as the cause of the symptoms. Other medical conditions that can cause similar symptoms, such as rheumatoid arthritis or gout, must be ruled out.
Medical tests that may be performed include the following:
- X-rays of the affected joints
- MRI of the affected joints
- Rheumatoid factor blood test, to rule out rheumatoid arthritis
- Uric acid levels, to rule out gout
X-rays may appear normal during early stages of psoriatic arthritis, but signs of inflammation develop over time, particularly in the distal joints of the fingers and toes.
An x-ray finding that is unique to psoriatic arthritis is the "pencil in the cup" appearance of the bone that narrows at the end, similar to a pencil.
There are a variety of treatments for psoriatic arthritis. Your doctor will recommend a treatment based on the severity of symptoms, results of past treatments, and your medical history.
Some medications that slow disease progression and miminize disabilty are described as DMARDs (Disease-modifying antirheumatic drugs).
Your doctor may prescribe medications to help manage your symptoms. Medications include:
- Aspirin and non-steroidal anti-inflammatory drugs (NSAIDs). These medications help to decrease inflammation, joint pain and stiffness. Some of these, such aspirin, ibuprofen (Advil® and Motrin®), and naproxen (Aleve®, Naprosyn®) are available over-the-counter. Others, such as ketoprofen (Orudis®), and diclofenac (Voltaren® and Arthortec®) require a prescription.
- COX-2 Inhibitors (Celebrex®). These provide similar symptom relief as NSAIDs, but may be considered by those who cannot tolerate the possibel GI side effects of aspirin and NSAIDs.
- Corticosteroids taken by mouth (prednisone). These reduce the inflammation and swelling in the joints. Because of the side effects that develop with prolonged use, oral corticosteroids are generally used for a limited time to get arthritis symptoms under control and then discontinued.
- Corticosteroid injections. Corticosteroids may be injected into some joints that are particularly inflamed without the side effects of taking corticosteroids by mouth
- Antimalarials. Some of the medication used to treat malaria have been an effective treatment for different types of arthritis. Antimalarials may need to be taken for several months before seeing the benefits of treatment. Antimalarials can lead visual changes, such as blurring, so those taking an antimalarial should have regular eye exams. (Note: Plaquenil is a commonly prescribed medication for malaria, but it is not recommended for patients with psoriasis because it can lead to a worsening of psoriasis symptoms.)
- Cyclosporine and Methotrexate (MTX). These medications are immunosuppressant that are commonly prescribed to treat psoriasis and may be used for the treatment for psoriatic arthritis. Patients taking cyclosporine and methotrexate are followed closely and may require routine blood tests.
- Sulfasalazine. This medication is routinely used to treat inflammatory bowel diseases (IBD), and has been found to provide rapid relief for some people with psoriatic arthritis. Routine blood tests may be required to monitor blood cell counts and liver enzymes.
- Leflunomide (Arava®)
- Azathioprine (Imuran®)
Biologics for Psoriatic Arthritis
Biologics (also called “immunomodulators” or “disease-modifying therapies”) are a relatively new treatment option for moderate to severe psoriasis and psoriatric arthritis. Biologics are especially effective at healing the progression of arthritis in patients with psoriasis.
Biologics are derived from human or animal proteins instead of chemicals. They work by targeting specific parts of the immune system such as T-cells or TNF, a chemical messenger used by immune cells. This focused approach reduces the likelihood of side effects that are seen following treatment with other medications that impact the entire immune system.
Biologics must be administered by injection, either into the skin (subcutaneously), into the muscle (intramuscular or IM), or by intravenous infusion (IV). Some biologics may require long-term use to keep psoriatic arthritis under control.
Biologics available for the treatment of psoriatic arthritis include:
- Etanercept (Enbrel®). Etanercept is a TNF-inihibitor that is also approved for the treatment of rheumatoid arthritis, ankylosing spondylitis and juvenile idiopathic arthritis. Enbrel® is administered subcutaneously 1-2 times per week.
- Adalimumab (Humira®). Adalimumab is a TNF-inhibitor that is also approved for the treatment of rheumatoid arthritis, juvenile idiopathic arthritis, ankylosing spondylitis and Crohn’s desease.Humira® is administered subcutaneously every other week.
- Certolizumab (Cimzia®)
- Infliximab (Remicade®). Infliximab is a TNF-inhibitor that is also approved for the treatment of ankylosing spondylitis, ulcerative colitis, rheumatoid arthritis and Crohn’s disease. It is adminstered via IV infusion in a doctor's office or infusion center. Three infusions are administered in the first 6 weeks of therapy, followed by infusions every 8 weeks.
- Golimumab (Simponi®). Golimumab is also approved for the treatment of rheumatoid arthritis and ankylosing spondylitis. It is administered subcutaneously once per month. Golimumab reduces the levels of TNF (tumor necrosis factor) in the body, but acts differently than other TNF inhibitors
- Ustekinumab (Stelara®)
- Exercise is generally recommended to preserve strength and maintain flexibility.
- Physical therapy and rehabilitation may be recommended to help to assist with mobility, adopt assistive devices, and to implement helpful measures around the home or at work.
- Splints may be used to properly position a joint to improve function and relieve pain.
- Surgery may be recommended in severe cases of joint pain that does not respond to medical treatment.
Reference: National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS)