Up to 30% of people with psoriasis also develop psoriatic arthritis. In psoriatic arthritis, joints become sore, stiff, and swollen. Untreated psoriatic arthritis can even cause permanent joint damage.
Psoriatic Arthritis: The Essentials
Everyone with psoriatic arthritis has both skin and joints affected, at some point. Most people have recognized psoriasis, followed by arthritis. In about 15% of people with psoriatic arthritis, the arthritis comes first, with no initial skin involvement. Another 15% with psoriatic arthritis have skin lesions diagnosed at the same time as arthritis, but don’t recognize them as psoriasis.
The symptoms of psoriatic arthritis include:
- Pain, stiffness and swelling in joints
- Morning stiffness
Psoriatic arthritis can affect other areas besides joints:
- Tendons, at the attachment point to bone.
- Fingers and toes, which can swell into “sausage digits.” Swelling can also affect the whole hand or foot.
- Fingernails and toenails, with pitting or crumbling of nails.
Psoriatic arthritis varies in severity. In some people, psoriatic arthritis causes mild aches and pains. Others are affected more severely. Psoriatic arthritis can be destructive to joints and even cause deformities or disability. In this aspect, psoriatic arthritis is similar to rheumatoid arthritis, although usually milder.
Is it Psoriatic Arthritis, or Psoriasis and Arthritis?
Not everyone with psoriasis and arthritis has psoriatic arthritis. People with psoriasis can develop other forms of arthritis, just like anyone else. The most common kinds of arthritis are:
- Osteoarthritis, the most common kind of arthritis overall. This is the “wear and tear” arthritis caused by aging and injury.
- Gout, arthritis characterized by attacks that occur when crystals deposit in the joints. Gout attacks are intensely painful, then subside over days.
- Rheumatoid arthritis, an autoimmune disease of the joints. Psoriatic arthritis is also an autoimmune disease, but is different from rheumatoid arthritis.
Diagnosis of Psoriatic Arthritis
There is no single test that accurately diagnoses psoriatic arthritis. Instead, doctors make the diagnosis of psoriatic arthritis based on all the available information taken together. Some tests a doctor might order to diagnose psoriatic arthritis include:
- Lab tests: anti-nuclear antibody (ANA), rheumatoid factor (RF), or anti-cyclic citrullinated peptide (anti-CCP) may be elevated in psoriatic arthritis. The antibody (ACPA) may be elevated in rheumatoid arthritis. The main value of these tests is to identify other conditions not as evidence in favor of PsA. They are also used to rule out other possible diseases, instead of being used for diagnosing psoriatic arthritis.
- Joint aspiration: Using a needle to withdraw fluid from a swollen joint can rule out gout and some other forms of arthritis.
- Radiology: Plain X-rays or magnetic resonance imaging (MRI) can identify joint damage caused by psoriatic arthritis and help differentiate it from other forms of arthritis.
If a doctor finds typical X-ray findings of psoriatic arthritis, psoriasis on the skin, and no other type of arthritis, it’s enough to make the diagnosis in most people with psoriatic arthritis. A rheumatologist (joint specialist) may be the most qualified to make the diagnosis of psoriatic arthritis.
Treatment of Psoriatic Arthritis
Psoriatic arthritis is treated much like rheumatoid arthritis. Common treatment includes drugs that might slow the process of joint damage in psoriatic arthritis (called disease-modifying antirheumatic drugs or DMARDs); and nonsteroidal anti-inflammatory drugs (NSAIDs), which treat symptoms without changing the course of psoriatic arthritis.
The drug apremilast (Otezla) doesn't fall into either of the above categories. It's an inhibitor of an enzyme called phosphodiesterase-4 (PDE-4). Otezla is FDA-approved to treat psoriatic arthritis and is taken orally.
Typically, the DMARDs reduce skin psoriasis as well as psoriatic arthritis. DMARDs include:
- Cyclosporine (Neoral, Sandimmune)
- Leflunomide (Arava)
- Methotrexate (Folex, Rheumatrex)
- Sulfasalazine (Azulfidine)
Biologic agents, include:
- adalimumab (Humira)
- adalimumab-atto (Amjevita), a biosimilar to Humira
- certolizumab (Cimzia)
- etanercept (Enbrel)
- etanercept-szzs (Erelzi), a biosimilar to Enbrel
- golimumab (Simponi)
- inflixirnab (Remicade)
- infliximab-dyyb (Inflectra), a biosimilar to Remicade
- ixekizumab (Taltz)
- secukinumab (Cosentyx)
- tocilizumab (Actemra)
- ustekinumab (Stelara)
Biologic agents are considered to prevent long-term joint damage.
Although DMARDs often slow joint damage in short-term studies, it remains to be seen whether they prevent long-term joint damage from psoriatic arthritis.
These medicines treat symptoms like pain, swelling, and stiffness. NSAIDs include aspirin, ibuprofen (Motrin), indomethacin (Indocin), naproxen (Naprosyn), and piroxicam (Feldene). NSAIDs improve symptoms but don’t affect the progression of joint damage.
Prognosis of Psoriatic Arthritis
Like skin psoriasis, psoriatic arthritis can’t be cured. With treatment, though, most people with psoriatic arthritis do well. Pain and swelling usually persist, but are controlled with pain medicines and DMARDs.
About 20% of people with psoriatic arthritis will develop a destructive form of the disease. Certain characteristics of psoriatic arthritis can help identify aggressive cases:
- Frequent or multiple effusions (fluid on the joint, making it swell)
- Involvement of more than five joints
- High level of medication use in the past for psoriatic arthritis
- Already having damage on X-rays or MRI scans, making future damage likely.
In people with joint damage or signs of aggressive psoriatic arthritis, DMARDs are the preferred treatment.
Psoriatic arthritis can be deceptive. Sometimes, psoriatic arthritis is only mildly painful, even when it’s destructive. If you have symptoms of psoriatic arthritis, see your doctor. Close follow-up and conscientious treatment could slow the process of joint damage.