According to the American College of Rheumatology, around 15 percent of people with psoriasis will develop a type of inflammatory arthritis, known as psoriatic arthritis (PsA). It's possible, however, for someone without the skin changes of psoriasis to develop PsA, especially if someone else in their family has the disease.
The symptoms of psoriasis are caused by immune system cells abnormally attacking healthy skin and joint tissue. This results in inflammation, swelling, and pain.
Doctors aren't sure why the immune system in some people attacks healthy tissue, although they believe genetics may play a role. This is because psoriasis and PsA tend to run in families.
In addition, environmental factors may also play a role. Injury, infection, or exposure to an environmental trigger can bring on PsA, especially in people with a family history of the disease.
People with PsA may have symptoms that come and go. The period of time when the symptoms worsen is known as a flare and tends to be triggered by something specific.
The symptoms of PsA may flare up if triggered by stress, exposure to cigarette smoke, or a host of other factors.
Common triggers include:
- infections or skin wounds
- severe stress
- cold weather
- exposure to cigarette smoke
- heavy alcohol use
- certain medications
Understanding what triggers PsA flares is essential to helping prevent them. Keeping a journal and recording information about what has happened before a PsA flare may help.
A person with PsA should keep an eye out specifically for these common triggers, or other factors that might be causing the symptoms. There are online trackers and apps available, but even just a simple pen and paper journal may be useful.
Sharing this information with a doctor can help identify effective treatments or simple lifestyle changes that could improve symptoms.
There are several risk factors that have been associated with developing PsA:
- Age: People between the ages of 30-50 are most likely to develop PsA. It is possible, however, for people of any age to get the disease.
- Family history: People with a family history of psoriasis or PsA are more likely to get the disease, than those without.
- Medical history: Having psoriasis is the biggest risk factor for getting PsA. In most cases, people develop PsA after they already have the rash of psoriasis, though it is possible for PsA to develop before any skin lesions appear.
The symptoms of PsA vary from person to person and can range from very mild to severe. They may include:
- painful and swollen joints that are warm to the touch
- swollen fingers and toes that look like sausages, known as dactylitis
- joint stiffness
- pain at the ends of ligaments and tendons
- foot pain, especially at the heel or sole of the foot
- lower back pain
- lower range of motion
- morning stiffness
- changes in the nail bed
- redness and pain in the eye
PsA can affect any joint, but is most common in the joints of the fingers, toes, lower back, wrists, knees, or ankles.
Both psoriasis and PsA cause episodes where the symptoms worsen, also known as flares. Most of the time, the symptoms will lessen between flares.
In most cases, a person with PsA will be diagnosed with psoriasis before developing the joint stiffness and pain associated with arthritis. However, some people will have symptoms of the arthritis before being diagnosed with psoriasis.
Types of PsA
Psoriatic spondylitis may lead to stiffness and pain in the neck.
There are five different patterns of PsA that have been identified, based on the number and types of joints involved. They are:
- oligoarticular - affects fewer than four joints
- polyarticular - affects five or more joints
- distal interphalangeal (DIP) - affects mostly the joints in the finger tips
- arthritis mutilans - a severe, debilitating form that can destroy the small bones in the fingers
- psoriatic spondylitis - causes arthritis in the spine, leading to stiffness and pain in the neck and back
A majority of cases are diagnosed as following the oligoarticular pattern of PsA. In addition, affected joints tend not to be equal on both sides of the body.
There is no single test for PsA. Instead, a doctor will need to rule out the presence of other conditions that cause the same symptoms, by using the following methods:
- looking at a person's medical history and a physical examination
- ordering X-rays of affected joints to look for damage
- ordering MRI or CT scans to look at the joints in more detail
- doing a rheumatoid factor blood test to make sure it is not rheumatoid arthritis
- testing for the presence of uric acid crystals in joint fluid if there is concern about gout
Symptoms of PsA can appear and then disappear before someone can get to the doctor, making diagnosis difficult. It's not uncommon for a person to have a few flares before the disease is diagnosed.
Anyone with a history of psoriasis and joint pain or swelling should see their doctor promptly. They should be sure to mention that they have psoriasis so that they can be properly evaluated.
Pain management is usually a major concern for people with PsA. There are many different options available and it can sometimes take a bit of trial and error before the best option is found.
Mild exercise and staying active can help to relieve painful joints and stiff muscles. Particularly effective exercises for patients with PsA include yoga and swimming. It's important for people to find an activity that is comfortable and then to stick with it.
Mild exercise, such as swimming and yoga, can help people with PsA effectively manage pain.
There are several different medications that can be used to treat symptoms and prevent joint damage in people with PsA. The doctor will select a medication based on the amount of pain, swelling and stiffness that the patient has.
- Non-steroidal anti-inflammatory drugs (NSAIDs), such as ibuprofen or naproxen, which can be very effective for mild cases.
- Disease-modifying anti-rheumatic drugs (DMARDs), such as sulfasalazine and methotrexate, to slow joint damage associated with psoriatic arthritis.
- Immunosuppressants, such as azathioprine and cyclosporine, to suppress the immune system, so reducing joint pain and swelling.
- TNF-alpha inhibitors, drugs that block the production of a chemical in the immune system that is responsible for inflammation and swelling. They also help to reduce pain.
Some of these drugs can have serious side effects and are not appropriate for everyone. It is important for people with PsA to see their doctor regularly, or call with any concerns.