There are key differences between the two autoimmune conditions, RA and PsA.
Rheumatoid arthritis (RA) and psoriatic arthritis (PsA) have some things in common. They’re both conditions that cause progressive joint damage — joint damage that causes stiffness, pain, and swelling, sometimes limiting a person’s physical ability.
RA and PsA are both autoimmune conditions, which means they cause the immune system to mistakenly attack itself.
But despite some similarities, PsA and RA are not the same.
If you live with either RA or PsA, you likely know firsthand how frustrating it can be when people misunderstand the differences.
RA and PsA are different in many ways. Co-occurring conditions and visibility, the age of onset, and the areas of the body affected can all differ.
PsA usually occurs in people who also live with psoriasis. This means that the disease affects both the skin and joints.
There’s often a visible difference between PsA and RA when PsA causes skin plaques. These plaques are raised, red rashes that are not usually itchy but can be scaly and even painful. They can be quite noticeable due to size and color and may be on parts of the body that are difficult to keep covered, like the elbows and knees.
PsA is sometimes categorized as a “milder” disease when compared to RA, but PsA’s impact on body image and self-esteem is major.
Research in 2017 suggests that these plaques often negatively affect the quality of life, self-esteem, and body image of people who experience them.
Plaques can appear on the scalp, nails, and even genitals. Researchers in 2018 note that genital plaques especially affect someone’s quality of life.
With PsA, body image concerns can be significant. According to a 2006 study, for people living with rheumatic disease, concerns about appearance were strongly related to depression.
Many rheumatological diseases are considered invisible illnesses. People with invisible illnesses often appear to be living without a disability even though they have one.
PsA challenges this invisibility by being visible as a rash or skin problem — but many wouldn’t suspect it’s an illness that causes pain throughout the entire body.
People living with PsA face different challenges than people living with RA do, within everyday life and the medical community.
Genetics play a part in the diagnosis of both RA and PsA, but they may play a different role in each disease.
You’re more likely to get a diagnosis of RA if you have a close relative with it and if you’re a woman. According to the CDC, the likelihood of being diagnosed with RA increases with age. The highest rate of diagnoses occur in people in their 60s. Obesity and smoking can also increase this risk.
PsA is more commonly diagnosed in younger populations, between ages 30–50. Researchers aren’t sure of the genetic components yet.
Research hasn’t found any correlations between genetics and triggers, but hormones and viral infections may play a role.
RA symptoms are usually on both sides of the body (symmetric), though one side may hurt more than the other.
People with RA usually report more morning stiffness upon waking. Many people with RA report fatigue, too. In some cases, people with RA can become quite sick with frequent fevers and unpredictable weight loss.
PsA affects both the joints and the skin. The plaques may also be on parts of the body that aren’t directly affected by arthritis, like the scalp and genitals. The joint pain associated with PsA is usually only on one side of the body (asymmetrical).
PsA can also affect more joints than RA, like the joints of the back and pelvis. It also tends to affect places where tendons and ligaments attach to bones, called entheses.
PsA can even make your nails brittle, causing peeling and flaking.
RA and PsA do have some similiarities.
A formal diagnosis of RA or PsA is most commonly made by a rheumatologist, a medical professional with specialized training in rheumatic and inflammatory conditions.
A combination of bloodwork, imaging, and going over a list of symptoms is what a rheumatologist uses to diagnose these diseases. It’s uncommon to have both PsA and RA.
For a diagnosis of RA, typically the rheumatoid factor (RF) and other labs will be positive or elevated. The rheumatologist will usually refer to the 2010 ACR/ EULAR Guidelines to guide their diagnosis and decisions.
For a diagnosis of PsA, labwork is usually normal and may or may not show elevated inflammatory markers. There’s usually skin involvement with PsA.
RA and PsA are similar in many ways, but it’s important to acknowledge the key differences between the two.
According to research in 2015, there are many differences at the clinical, immunological, cellular, and molecular levels. There’s also a difference in response to treatments.
It will take time for research to find and confirm all of these differences, but research in the field of rheumatology has come a very long way and continues to improve each day.
Medically reviewed on July 31, 2022
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