Psoriatic arthritis (PsA) and rheumatoid arthritis (RA) are both inflammatory, autoimmune conditions. Their symptoms are similar, including joint stiffness, pain, inflammation, and exhaustion.
Because they’re both types of arthritis, many people aren’t sure about the differences and relationship between PsA and RA. As one MyPsoriasisTeam member asked, “Is there a link between psoriasis and rheumatoid arthritis?”
Ultimately, there are a few key similarities and differences between the causes, symptoms, and treatment of PsA and RA.
Psoriatic arthritis occurs when the immune system mistakenly attacks the body’s own healthy tissues instead of foreign invaders, like viruses and bacteria. Unlike rheumatoid arthritis, psoriatic arthritis is related to another condition called psoriasis. The autoimmune disease psoriasis causes scaly, red patches on the skin, which can burn or itch.
Rheumatoid arthritis is the most common type of inflammatory arthritis, affecting more than 1.3 million people in the United States. Like PsA, it occurs when the immune system attacks the joints’ healthy cells and tissues. RA, in particular, targets the lining of the membranes surrounding the joints (called the synovium), causing inflammation and permanent joint damage.
Some of the causes of PsA and RA overlap, and others are specific to PsA.
Rheumatoid arthritis is caused by the immune system attacking the synovium, leading to inflammation. Over time, the thickened synovium can damage the cartilage and bone within the joint.
As is the case with PsA, the exact cause of rheumatoid arthritis is unknown. Scientists believe environmental factors (such as smoking, pollution, or infections), in combination with genetic factors, trigger the autoimmune response characteristic of RA. If you have a family history of RA, you are more likely to develop it, as well.
It’s not entirely clear why the immune systems of people with PsA attack their healthy tissues. However, like RA, both genetic and environmental factors, as well as family history and genes, are thought to contribute to the development of PsA.
Most people who develop psoriatic arthritis show the skin symptoms of psoriasis first, although some individuals experience PsA without ever having psoriasis symptoms. About 30 percent of people with psoriasis will eventually develop PsA.
The severity of a person’s psoriasis symptoms is not linked to the severity of their PsA symptoms. Some people may have severe psoriasis skin lesions but mild PsA symptoms, and others may have mild skin lesions but severe PsA joint pain.
Both psoriatic arthritis and rheumatoid arthritis cause similar joint symptoms. Joints affected by PsA or RA can feel painful, stiff, swollen, and hot. The symptoms of PsA and RA tend to show up in different joints.
The two diseases, for instance, affect different parts of the spine. PsA sometimes leads to a condition called spondylitis that causes lower back pain. Spondylitis involves inflammation in the joints of the spine and between the spine and pelvis. Up to half of people with PsA will experience spondylitis pain. RA, on the other hand, often causes problems in the cervical spine, in the neck. Up to 80 percent of people with RA experience neck pain.
RA is also more likely than PsA to affect the hands, such as the joints in the wrists and fingers, whereas PsA is more likely to affect the feet. Additionally, PsA and RA affect different small joints within the fingers and toes. RA affects the first two joints, and PsA attacks the joint closest to the nail bed.
People with PsA can experience dactylitis, a condition in which the fingers or toes swell up and resemble sausages. Dactylitis is often the first symptom of PsA, and it may be the only joint symptom a person experiences for several years. PsA also affects the nails. People with PsA often have pitted, ridged nails, which appear similar to nails with a fungal infection.
Another difference between the two diseases is whether they affect one or both sides of the body. PsA tends to be asymmetric, meaning it affects different joints on either side of the body. RA is more likely to cause symmetrical joint pain and stiffness — it affects the same joints on both sides of the body, such as both hands or wrists.
Some MyPsoriasisTeam members have shared that diagnosing PsA and RA can be tricky. One member asked, “How can they know for certain if you have psoriatic arthritis or rheumatoid arthritis? I’ve had all kinds of blood tests done!”
Another member shared, “It’s difficult, but they know what to look for. [PsA] affects different joints in the fingers than rheumatoid arthritis. The best way to find out is to see a rheumatologist.”
Ultimately, there are several ways a rheumatologist can diagnose PsA and RA.
Imaging tests, such as X-rays and magnetic resonance imaging (MRI), are useful in diagnosing both PsA and RA, as well as learning how far the disease has advanced.
X-rays are the first line of diagnosis for both conditions, as they are inexpensive and easy to reproduce. More sensitive technologies, like MRI, are costlier and are therefore used as second-line diagnostic tools.
PsA and RA can produce different patterns of inflammation on imaging scans, and ultrasound can be useful in detecting these patterns and getting a definitive diagnosis.
Blood tests can also help tell the difference between PsA and RA.
About 80 percent of people with RA are said to have seropositive RA, which means they test positive for rheumatoid factor (RF) or for cyclic citrullinated peptide (CCP) antibodies.
Many of the same treatment options are used to treat both PsA and RA.
Over-the-counter nonsteroidal anti-inflammatory drugs (NSAIDs), such as Aspirin and Ibuprofen, are useful for managing mild to moderate symptoms of psoriatic arthritis and rheumatoid arthritis. These drugs can help to reduce inflammation and swelling.
Corticosteroid joint injections can provide quick relief for PsA and RA symptoms. But the side effects associated with steroid use — and with oral steroids in particular — mean these medications are not a good long-term option for treating joint pain.
Additionally, corticosteroid discontinuation can make psoriasis flare-ups more volatile in people who have PsA.
Disease-modifying antirheumatic drugs (DMARDs) have been proven in clinical studies to stop or slow the disease process in people with inflammatory arthritis. Methotrexate is the most commonly used DMARD for RA. It may not be as effective in treating PsA, although studies show mixed results.
Biologic DMARDs, such as Enbrel (Etanercept), Remicade (Infliximab), and Humira (Adalimumab), are approved by the U.S. Food and Drug Administration (FDA) for PsA and for moderate to severe RA. Some of these drugs may be taken along with Methotrexate.
Biologic DMARDs may be given for severe cases of PsA or when other drugs haven’t worked.
The medications Cosentyx (Secukinumab), Taltz (Ixekizumab), Stelara (Ustekinumab), and Tremfya (Guselkumab) help block the production of certain proteins called interleukins. These proteins regulate cell growth and stimulate inflammation. These drugs, however, do not help treat RA.
Inflammation in RA is associated with a different interleukin (called IL-6) than those in PsA. The IL-6 inhibitor drugs Actemra (Tocilizumab) and Kevzara (Sarilumab) work against RA, but have not been proven to help with PsA.
In addition, Rituxan (Rituximab) and Kineret (Anakinra) can be helpful for RA that has not responded to other types of treatment. However, these drugs are not useful in treating PsA.
You can have both PsA and RA. However, because it’s also possible to have just one of the conditions, you should talk to your doctor or rheumatologist if you are confused about your symptoms. Additionally, some people with PsA never experience the obvious skin disease symptoms of psoriasis, making it easy to confuse PsA with RA.
In people who have both PsA and RA, the symptoms may sometimes overlap or come and go. As one MyPsoriasisTeam member shared, “My psoriasis has cleared up a lot, but my rheumatoid arthritis and psoriatic arthritis have gotten worse.”
MyPsoriasisTeam is the social network for people with psoriatic arthritis and psoriasis and their loved ones. Here, more than 87,000 members come together to share their stories, ask and offer advice, and discuss life with both PsA and RA.
Those diagnosed with RA may consider joining myRAteam, a support network for rheumatoid arthritis that is more than 142,000 members strong.
Have you been diagnosed with PsA and RA, or are you wondering if you may have RA in addition to your PsA? Let us know in the comments below, or start a conversation on MyPsoriasisTeam. You'll be surprised just how many others may share similar stories.
Easily manage your subscription from the emails themselves.