Psoriatic Arthritis and Rheumatoid Arthritis

What’s the Difference?: Psoriatic Arthritis and Rheumatoid Arthritis

Here’s what you need to know to tell these two forms of arthritis apart.

Both psoriatic arthritis and rheumatoid arthritis are autoimmune diseases in which the immune system attacks the joints, causing inflammation and pain. Indeed, it is easy to confuse the two conditions because of similar symptoms

 

Both psoriatic arthritis and rheumatoid arthritis are autoimmune diseases in which the immune system attacks the joints, causing inflammation and pain. Indeed, it is easy to confuse the two conditions because of similar symptoms. Psoriatic arthritis and rheumatoid arthritis (RA) are just two of the more than 100 forms of arthritis, according to the Arthritis Foundation.

“People equate joint pain to inflammatory arthritis, but there are many causes of joint pain not due to arthritis,” says Jeffrey Sparks, MD, a rheumatologist at Brigham and Women’s Hospital in Boston. “You need a trained rheumatologist to make sure diagnosis and treatment are correct,” Dr. Sparks says.

Here are the main differences between the two 

Skin Lesions Versus None

People with psoriatic arthritis often have skin lesions that appear on the body. Psoriatic arthritis patients usually have a history of psoriasis, a skin condition that causes itchy, dry red patches and thick, silvery scales on the skin. “It can sometimes be painful and embarrassing,” Sparks says.

study published in January 2015 in Rheumatology found that skin lesions precede arthritis in more than 80 percent of psoriatic arthritis patients, and can sometimes occur more than a decade before arthritis.

RA, on the other hand, is a condition that affects only the joints.

Location of Joint Pain

Although both psoriatic arthritis and rheumatoid arthritis affect the whole body, psoriatic arthritis is asymmetrical and tends to affect different joints on different sides of the body. Rheumatoid arthritis is symmetrical, with joint pain occurring on both sides of the body. So if a person with RA experiences pain in the right hand, symptoms will occur in the left hand, too.

Related: Rheumatoid Arthritis vs. Osteoarthritis Joint Pain

The two conditions also differ in where joint pain occurs in the body. “RA usually affects small joints,” says Elaine Husni, MD, MPH, vice chair of the department of rheumatic and immunological diseases at the Cleveland Clinic in Ohio. “In psoriatic arthritis, not only do you have joint swelling, but enthesitis [pain where the tendon inserts into the bone] and dactylitis [inflammation of an entire digit, known as sausage digit]. Those two are very unique to psoriatic arthritis.”

The Presence of Back Pain

Dr. Husni also says that unlike RA, psoriatic arthritis manifests itself with back pain. Symptoms of psoriatic arthritis also include stiffness, primarily in the neck and upper and lower back.

study published in RMD Open Rheumatic & Musculoskeletal Diseases in April 2015 looked at the differences between psoriatic arthritis and RA and found that because the sacroiliac joints (which connect the sacrum with the pelvis) and the lumbosacral spine (where the lumbar spine meets the sacrum) are affected by psoriatic arthritis, the condition is included in the spectrum of spondyloarthropathies — joint diseases of the vertebral column.

Changes in Nails

“Nails can be helpful in distinguishing between the two conditions as well,” Sparks says. Psoriatic arthritis can also affect the fingernails and toenails and can result in pits on the nail or separation of the nail from the nail bed. Sparks adds that this is thought to occur as a result of inflammation where the nail bed originates.

Ways to Treat the Conditions

The same April 2015 study mentioned above reports that “First-line disease modifying antirheumatic drugs (DMARDs), such as methotrexate (MTX) and leflunomide [Arava]are effective in the management of both RA and psoriatic arthritis.” Beyond that, however, treatment and management of the conditions are different.

Methotrexate [Trexall] is the first drug used in either condition,” Sparks says. “[Afterward,] management does change depending on which you have.”

Along with medication, the Mayo Clinic states that treatment for RA may include physical therapy to help you learn exercises to keep joints flexible, or surgery to repair joints and tendons.

Related: Rheumatoid Arthritis Can Be an Invisible Illness

Husni says that the best treatment for psoriatic arthritis will encompass both skin and joint disease. “In addition, a subset of psoriatic arthritis patients require additional treatment for nail and scalp involvement and for dactylitis and enthesitis involvement.”

But before you start on any treatment regimen, Husni says, “have an initial evaluation by a rheumatologist. They understand the landscape better.”

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