Psoriatic arthritis is a common condition affecting 2-3% of the population worldwide. About 1 in 3 people who have psoriasis will eventually develop psoriatic arthritis (1).
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What is Psoriatic Arthritis?
Psoriatic arthritis is a type of inflammatory arthritis that occurs in some people with the skin condition psoriasis. Psoriasis is an autoimmune disease in which the body’s immune system targets the cells of the skin, resulting in scaly red and white patches. Psoriasis typically begins during adolescence or young adulthood. This type of arthritis is also an autoimmune condition, though instead of targeting the skin like psoriasis, the immune system targets the joints resulting in pain, stiffness, and swelling.
Psoriatic arthritis can affect any joint in the body. For some people, the symptoms are mild, with only occasional flare-ups and few joints affected. In other people, the symptoms are continuous and can lead to joint damage if not treated due to the persistent inflammation from psoriatic arthritis. This makes early diagnosis and treatment essential to avoid long-term damage to the joints.
Symptoms of Psoriatic Arthritis
Psoriatic arthritis can cause several different symptoms which can range from mild to severe. The symptoms also affect different body systems including the skin, joints, tendons, ligaments, eyes, and nails. The symptoms are different for each person and appear between ages 30 and 50, though psoriatic arthritis can occur at any age. Symptoms may also vary in intensity and can get worse for a while, called a flare, which can happen between times of remission when a person may be symptom-free.
- Skin: Painful and itchy red patches or a white buildup of dead skin cells which most commonly occurs on the knees, elbows, and scalp. This rash is non-contagious and can occur anywhere on the body.
- Joints: Psoriatic arthritis most commonly affects the fingers, wrists, ankles, and knees. It causes symptoms such as pain, tenderness, warmth, and swelling. Joints may feel stiff with less range of motion, especially in the morning. Sometimes one individual finger or toe will swell, taking on a “sausage-like” appearance, and making it painful and hard to move. This is referred to as dactylitis.
- Spine: Psoriatic arthritis can also affect the spine leading to pain and stiffness in the low back, neck, and sacroiliac joints. When psoriatic arthritis affects the spine it is referred to as spondylitis.
- Nails: Symptoms of psoriatic arthritis in the nails include cracking, pitting, white spots, and lifting from the nailbed.
- Eyes: Some people with psoriatic arthritis experience eye redness and eye pain, which is called uveitis.
- Tendons/ligaments: Inflammation from psoriatic arthritis commonly affects the places in a body where tendons or ligaments attach to bone. This attachment point is called an enthesis. Common spots where inflammation occurs at entheses are at the back of the heel and the bottom of the foot.
- Fatigue: Many people with psoriatic arthritis experience significant tiredness and can even have a chronic low-grade fever. The fatigue comes from the systemic inflammation present in the body due to the disease process of psoriatic arthritis.
Psoriatic arthritis shares many of the same symptoms as rheumatoid arthritis, though rheumatoid usually affects symmetrical joints on body sides of the body. Scaly skin and nail changes are more likely associated with psoriatic arthritis.
Types of Psoriatic Arthritis
There are 5 different types of psoriatic arthritis which are determined by which parts of the body are affected and the extent of inflammation present.
- Symmetric Psoriatic Arthritis affects the same joints on both sides of the body. Typically this will include multiple pairs of joints, such as both knees, hands, or feet. This is the most common type of psoriatic arthritis.
- Asymmetric Psoriatic Arthritis does not affect the same joints on both sides of the body. Typically it will affect fingers and toes first which can lead to a “sausage-like” appearance due to the inflammation. Sometimes larger joints are also affected. This type is usually mild.
- Distal Psoriatic Arthritis affects the tips of the fingers and toes. It may also change the way the nails look with signs including pitting, discolored spots, and lifting away from the nailbed.
- Spondylitis affects the joints in the spine including the neck, lower back, and sacroiliac joints. If left untreated, the vertebrae in the spine may fuse together.
- Arthritis Mutilans is the most severe type of psoriatic arthritis. The bone cells are prevented from breaking down and rebuilding in this form of psoriatic arthritis which can deform the joints in the fingers, hands, wrists, and feet. This type of psoriatic arthritis is the rarest (2).
Psoriatic arthritis progresses differently for each individual. Some people only ever experience mild symptoms which do not impact the long term health of their joints. For others, deformities occur at the joints with a significant impact on the ability to perform daily tasks.
- Early stage: The early stages of psoriatic arthritis involve mild symptoms such as joint swelling and stiffness. Symptoms in this stage may be confused for other symptoms. Inflammation at the Achilles tendon may be diagnosed as a typical tendinopathy or an overuse injury. People at this stage may be able to manage their symptoms with over-the-counter treatments.
- Moderate-stage: Psoriatic arthritis in the middle stage will likely present with worsening symptoms. This stage typically requires more aggressive treatments that stop the progression of the disease.
- Late stage: People with late-stage psoriatic arthritis experience joint deformities and significant symptoms. Permanent bone damage is possible which occurs from prolonged periods of inflammation. Treatments will aim to ease symptoms and prevent complications.
Risk Factors & Causes of Psoriatic Arthritis
Psoriatic arthritis is characterized by an overactive immune system that attacks the joints and skin. It is not known for sure what causes psoriatic arthritis, but research supports that it is a combination of genetics, immunity, and environmental factors.
- Genes: Researchers have identified changes in several genes that may increase the risk of developing psoriatic arthritis. The most well-known of these genes are in the human leukocyte antigen (HLA) complex. This complex helps the immune system distinguish the proteins that are made from foreign invaders, for example, proteins made by viruses, as different than the body’s own proteins. Variations in several different HLA genes can increase the risk of developing psoriatic arthritis. The changes in the HLA genes can also influence the type of psoriatic arthritis you develop as well as how severe it is (3).
- Inheritance: Having a family member with psoriatic arthritis can increase your risk of developing the condition. Approximately 40% of those diagnosed with psoriatic arthritis have at least one close family member with psoriasis or psoriatic arthritis.
- Immunity: Some people develop psoriatic arthritis after an infection that increases the immune response. For example, psoriasis is commonly triggered by strep throat (4).
- Environmental Factors: Other environmental factors such as a virus, extreme or prolonged stress, or an injury can trigger psoriatic arthritis.
The diagnosis of psoriatic arthritis is usually made by a rheumatologist. This type of doctor specializes in inflammatory diseases that affect muscles, bones, ligaments, and joints. The doctor will take your medical history and symptoms in combination with imaging and blood tests to make a diagnosis of psoriatic arthritis and rule out other types of arthritis. A diagnosis of psoriatic arthritis cannot be made by a single test, but your doctor will synthesize the results of several different exams to come up with an accurate diagnosis.
Scans can look for damage to joints and other tissues that may support the diagnosis of psoriatic arthritis. X-rays can check for inflammation and damage to bones and joints. An MRI might be ordered to check for joint, tendon, or ligament damage. CT scans are also sometimes used to determine how advanced psoriatic arthritis is and how progressed the joint deformities have become.
- C-reactive protein: an elevated C-reactive protein indicates that there is increased inflammation in the body. This protein is made by the liver and can be elevated no matter what the inflammation is caused by.
- Erythrocyte sedimentation rate: similar to C-reactive protein, this test shows how much general inflammation is present. It can not determine if the inflammation is due to psoriatic arthritis, but may be a marker of the severity of the disease.
- Rheumatoid factor: rheumatoid factor is an antibody that is usually present in those with rheumatoid arthritis, but not those with psoriatic arthritis. It can help your doctor determine what type of arthritis you have.
- Joint fluid: a procedure called arthrocentesis removes a small amount of fluid from an affected joint. The fluid will be examined and if uric acid crystals are present, this would indicate a diagnosis of gout which is another inflammatory condition that can cause similar symptoms to psoriatic arthritis. Joint fluid can also be examined to rule out infection and sepsis.
- Red blood cells: a low count of red blood cells is caused by anemia and commonly occurs in people with psoriatic arthritis.
Treatment Options for Psoriatic Arthritis
The overall treatment goals for psoriatic arthritis are to improve symptoms such as skin rash and joint inflammation to the point of remission if possible. There are several different treatment options for those diagnosed with psoriatic arthritis.
- Nonsteroidal anti-inflammatory drugs (NSAIDs): NSAIDs include over-the-counter medication such as Ibuprofen and Naproxen. They can also be prescribed by a doctor. NSAIDs are used to reduce inflammation and ease symptoms and are typically most effective for those with mild or early-stage psoriatic arthritis. A common side effect is stomach irritation and more severe side effects may include heart problems, liver, and kidney damage.
- Disease-modifying antirheumatic drugs (DMARDs): This class of drugs is used to slow the progression of psoriatic arthritis. DMARDs may save joints and other tissues from permanent damage. Side effects may include liver damage, immune and bone marrow suppression, and lung scarring.
- Biologics: These drugs are a special class of DMARDs that target different pathways of the immune system. They are usually taken by injection or infusion. There are two groups of biological therapy sued to treat psoriatic arthritis. Biologics are immunosuppressant drugs and may increase the risk of infections.
- Steroids: Steroids can be administered by either injection or pill form. Steroids can be injected into inflamed joints to reduce pain and swelling, though the effects wear off after a few months. Getting too many steroid injections into one joint can have side effects such as causing damage to the surrounding tissues, so typically a maximum of 3 injections into each specific joint will be prescribed. Steroid pills can be useful if many joints are swollen and painful. Side effects of long-term steroid use include weight gain and osteoporosis, which is a condition that weakens bones and increases the risk of fracture.
There are a number of different topical treatment options that can be used for the rash that psoriasis causes. Ointments, creams, and gels can be applied to the skin to reduce painful and itchy patches of irritated skin. These topical treatments may include a medicine called dithranol, steroids, or salicylic acid.
If creams and ointments do not resolve the symptoms of psoriasis, light therapy may be recommended. This involves being exposed to strong ultraviolet light which can suppress the immune system, reduce inflammation, and allow the skin to heal. Possible side effects include a sunburn-like reaction, dark spots on the skin, and itching (5).
An anti-inflammatory diet may help with the symptoms of psoriatic arthritis. Foods that contain omega-3s have been well studied and shown to be anti-inflammatory. Eating omega-3s on a regular basis can decrease disease activity and joint tenderness. The best sources of omega-3s include fatty fish, seaweed, hemp seeds, flaxseed oil, chia seeds, walnuts, and edamame. High-antioxidant fruits and vegetables can help to reduce oxidative stress from chronic inflammation. The best sources of antioxidants are dark berries, dark leafy greens, nuts, and dried ground spices. High-fiber whole grains such as whole wheat, brown rice, and quinoa have also been linked to reducing chronic inflammation (6).
On the other hand, limiting inflammatory foods is also important to reduce the symptoms of psoriatic arthritis. These inflammatory foods include red meat, dairy, processed foods, and alcohol.
There are many lifestyle and self-care factors that can help with the symptoms of psoriatic arthritis. Protecting the skin by keeping it moisturized with regular use of lotions or creams can help manage psoriasis. Managing stress is also important because stress can worsen flares. Options to reduce stress include meditation, yoga, exercise, and joining a support group. Avoiding smoking and excessive alcohol use is also important.
A small percentage of people with psoriatic arthritis develop arthritis mutilans, the most severe type of psoriatic arthritis. It involves severe symptoms and is often disabling causing daily tasks to be difficult. Damage to the small bones in the hands and fingers leads to permanent deformity and disability.
People with psoriatic arthritis are also at a higher risk for developing other syndromes such as hypertension, metabolic syndrome, diabetes, and cardiovascular disease. Obesity is also a common cardiovascular risk factor in psoriatic disease (7).
Psoriatic arthritis can affect several body systems including the skin, joints, eyes, tendons, and nails. The most common joints affected are the hands, wrists, ankles, and knees though any joint in the body may be symptomatic. Pain levels vary depending on age, severity, and diagnosis. The most common symptoms are painful and itchy red patches on the skin, stiffness in the joints with swelling and pain, and tendon inflammation at the attachment points onto the bone.
Genetics is the main factor in who gets diagnosed with psoriatic arthritis. Having a close family member with psoriasis or psoriatic arthritis increases your chances of being diagnosed with the condition. Psoriatic arthritis may also be diagnosed after a viral infection, extreme stress, or injury. A combination of medical history, imaging, and blood tests will determine the diagnosis of psoriatic arthritis.
There are many different treatment options available to help with pain management and skin changes. These include medications, light therapy, topical treatments, and lifestyle factors. If you feel you have the symptoms of psoriatic arthritis, consult your healthcare provider to learn more about your options today. The quicker you take action, the less pain you will likely have in the long term.